Immunoglobulins in children with epilepsy: the Dutch Study of Epilepsy in Childhood

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1 Blackwell Sciece, LtdOxford, UKCEICliical ad Experimetal Immuology9-914Blackwell Publishig Ltd, Origial Article Cli Exp Immuol 23; 132:144 1 Immuoglobulis i childre with epilepsyp. M. C. Callebach et al. Immuoglobulis i childre with epilepsy: the Dutch Study of Epilepsy i Childhood P. M. C. CALLENBACH*, C. M. JOL-VAN DER ZIJDE, A. T. GEERTS, W. F. M. ARTS, C. A. VAN DONSELAAR, A. C. B. PETERS, H. STROINK**, O. F. BROUWER* & M. J. D. VAN TOL *Departmet of Neurology, Leide Uiversity Medical Cetre, Leide, Departmet of Paediatrics, Leide Uiversity Medical Cetre, Leide, Departmet of Neurology, Erasmus Medical Cetre Rotterdam, Rotterdam, Departmet of Paediatric Neurology, Erasmus Medical Cetre Rotterdam ad Sophia Childre s Hospital, Rotterdam, Departmet of Paediatric Neurology, Uiversity Medical Cetre Utrecht, ad Wilhelmia Childre s Hospital, Utrecht, **Departmet of Paediatric Neurology, St. Elisabeth Hospital, Tilburg, ad Departmet of Neurology, Uiversity Hospital Groige, Groige, the Netherlads (Accepted for publicatio 18 December 22) SUMMARY I a uselected cohort of 282 childre, serum immuoglobuli (Ig) cocetratios were determied shortly after the first presetatio with oe or more uprovoked epileptic seizures ad before the start of treatmet with ati-epileptic drugs (AEDs), ad after 9 18 moths of AEDs use. At itake, IgA, IgG1, IgG2 ad IgG4 cocetratios were sigificatly higher tha published referece values i healthy age-matched cotrols. I a subset of 127 childre, Ig levels at itake were compared with those after AEDs use for 9 18 moths. IgA ad IgG4 levels had decreased sigificatly to ormal cocetratios, but IgG1 ad IgG3 levels icreased sigificatly. To determie the ifluece of AEDs, Ig levels i childre who used carbamazepie or valproic acid mootherapy were aalysed separately. The use of carbamazepie was associated with a sigificat decrease of IgA ad IgG4 levels, ad the use of valproic acid with a sigificat decrease of IgA ad icrease of IgG1 levels. I coclusio, humoral immuity is already altered i childre shortly after the first presetatio with epileptic seizures. Whether this is the cosequece of a exogeous evet, ad to what extet this is related to a iteractio of the cetral ervous system ad the immue system, remais to be evaluated. Treatmet with AEDs, such as carbamazepie ad valproic acid, is associated with sigificat chages of Ig (sub)class cocetratios. Keywords carbamazepie childre epilepsy immuoglobulis valproic acid INTRODUCTION Based o the bidirectioal iteractio betwee the cetral ervous system (CNS) ad the immue system, it is attractive to speculate that immue mechaisms may be ivolved i the pathogeesis of at least some forms of epilepsy or that epileptic seizures may affect the immue system idirectly [1,2]. The implicatio of autoimmue mechaisms i the developmet of epilepsy has bee demostrated most covicigly for Rasmusse s ecephalitis, i which atiglutamate receptor 3 atibodies reactig with euroal atige probably play a cetral role i the disease process [3]. Aother argumet for immuological mechaisms beig Correspodece: M.J.D. va Tol, Departmet of Paediatrics, Leide Uiversity Medical Cetre, PO Box 96, 23 RC Leide, the Netherlads. m.j.d.va_tol@lumc.l ivolved is the observatio that some patiets sufferig from this ad other forms of itractable epilepsy, i.e. West sydrome, Leox Gastaut sydrome ad Ladau Kleffer sydrome, may beefit from treatmet with itraveous immuoglobulis (IVIg) [4,5]. The mechaism of actio of IVIg remais, however, curretly ukow. May reports have bee published cocerig the effects of the treatmet with ati-epileptic drugs (AEDs), e.g. pheytoi [6 9], carbamazepie [1 13] ad valproic acid [14 16], o humoral ad cellular immuity. From these studies, it became clear that a reversible iductio of a selective IgA deficiecy might occur i some patiets receivig pheytoi [8], ad that carbamazepie medicatio might be associated with selective reductio of the IgG2 subclass cocetratio [11]. However, useful iterpretatio of the results of the majority of the publicatios is hampered by the lack of data obtaied shortly after the oset of seizures ad before the start of treatmet. Furthermore, the studied populatios are relatively small, limited maily to adult Blackwell Publishig Ltd

2 Immuoglobulis i childre with epilepsy 145 patiets, or cotaied a heterogeeous populatio of adults ad childre. We ivestigated serum immuoglobulis i a large cohort of childre from their first presetatio with uprovoked epileptic seizures owards. Here, we preset quatitative data of the major immuoglobuli (Ig) isotypes ad IgG subclasses i serum samples obtaied at itake ad after use of AEDs for 9 18 moths. The effects of carbamazepie or valproic acid give as mootherapy o Ig serum levels were ivestigated separately. METHODS Patiets Durig a iclusio period of 4 years, 556 childre aged 1 moth to 16 years presetig i oe of the participatig hospitals with oe or more ewly diagosed uprovoked seizures or at least oe status epilepticus were erolled i the Dutch Study of Epilepsy i Childhood. Detailed iclusio ad exclusio criteria ad ivestigatios performed are reported elsewhere [17 19]. Oly if a child had experieced two or more seizures did the paediatric eurologist cosider whether to treat the child ad select the AEDs. Valproic acid ad carbamazepie were used as first-lie drugs i all childre [17]. The epilepsy was judged ot to be cotrolled adequately if at least two first-lie ad oe secod-lie drug were tried up to maximum tolerated dosages usuccessfully. Three paediatric eurologists ivolved i the study classified idepedetly the seizures ad epilepsy sydromes as idiopathic, remote symptomatic or cryptogeic accordig to the revised classificatios of the Iteratioal League Agaist Epilepsy (ILAE) [2,21]. Idiopathic epilepsies are epileptic sydromes with particular cliical characteristics ad with specific EEG fidigs. They are of ukow origi but have a presumed geetic aetiology. Remote symptomatic epilepsies are cosidered the cosequece of a kow or suspected disorder of the cetral ervous system resultig i a static ecephalopathy. Cryptogeic epilepsies are epilepsies of ukow origi that do ot coform the criteria for the symptomatic or idiopathic categories [22]. All metally retarded childre with epilepsy of ukow aetiology were classified as havig remote symptomatic epilepsy. Outcome was assessed with the help of the termial remissio: if the child had bee seizure-free for 12 moths or more at the ed of the follow-up of 5 years, outcome was qualified as good, if 6 12 moths as fair, ad if less tha 6 moths as poor [19]. The study had bee approved by the medical ethical committees of all participatig hospitals. Parets or caregivers gave their writte iformed coset. Immuology For several reasos, e.g. protocol deviatios by the paediatric eurologist ad refusal of the parets, serum samples were ot available from 274 of the 556 childre who met the iclusio criteria ad were erolled i the Dutch Study of Epilepsy i Childhood. Samples were obtaied from the remaiig 282 childre at itake aloe ( = 5) or at itake ad after the use of AEDs for 9 18 moths ( = 127) ad stored at -2 C. Serum cocetratios of IgM ad IgA were quatified by sigle radial immuodiffusio (Edoplates, Kallestad, Austi, TX, USA) or ephelometry (BN 1 ephelometer, Behrig, Marburg, Germay; atisera from Behrig). The cocetratios of IgG1, IgG2, IgG3 ad IgG4 were measured by dot-immuobidig assay as previously described [23] or ephelometry (BN 1 ephelometer; atisera from the Cetral Laboratory of the Netherlads Red Cross Blood Trasfusio Service (CLB), Amsterdam, the Netherlads). To validate that the reported media ad rage of Ig (sub)class cocetratios i serum samples of age-matched cotrols (referece values for IgM ad IgA: Cejka et al [24], referece values for the IgG subclasses: CLB, 1997 [25]) could be applied i our experimetal settig, serum samples obtaied from 76 healthy childre were aalysed. This cotrol group cosisted of siblig doors for recipiets of a HLA-idetical boe marrow graft that were trasplated at the Departmet of Paediatrics of the Leide Uiversity Medical Cetre. Statistical aalysis Normal distributio was tested with the Kolmogorov Smirov test. Cliical characteristics were compared betwee the childre from whom a blood sample was take at itake ad the childre from whom o blood sample was take, ad betwee childre from whom two blood samples were obtaied (at itake ad after AEDs use for 9 18 moths) ad childre from whom oly a blood sample was obtaied at itake usig the Pearso c 2 test (sex, aetiology, distributio epilepsy sydromes) ad the Ma Whitey rak-sum test (age at oset, Ig ratios). Furthermore, differeces i cliical characteristics betwee the distictive aetiologies were aalysed with the Kruskal Wallis test (age at takig blood sample ad outcome) ad the Pearso c 2 test (distributio epilepsy sydromes). Because ormal rages of Ig (sub)classes are age-depedet for each (sub)class, we corrected for age by calculatig ratios: the observed Ig (sub)class cocetratio of each child was divided by the reported media Ig (sub)class cocetratio i healthy childre of the correspodig age group [24,25]. Usig the Wilcoxo siged-raks test, we tested whether the calculated ratios i the cohort of which a blood sample was obtaied at itake differed sigificatly from 1 (if the ratio was 1, the observed Ig cocetratio equalled the media cocetratio of the correspodig age), ad whether Ig ratios differed betwee itake ad after AEDs use for 9 18 moths. Results were adjusted for multiple testig with the Boferroi correctio. Furthermore, we tested whether childre with Ig cocetratios outside the ormal rage of the correspodig age group differed from childre with Ig cocetratios withi the ormal rage with regard to age, aetiology, distributio of epilepsy sydromes ad outcome applyig the Pearso c 2 test (aetiology, distributio of epilepsy sydromes) ad the Ma Whitey rak-sum test (age, outcome). We also tested whether the Ig ratios differed betwee the group with oe seizure ad the group with multiple seizures (Ma Whitey rak sum test) or betwee the differet epilepsy sydromes as classified by the ILAE (Kruskal Wallis test) [21]. RESULTS At itake, a blood sample was take of 282 (51%; 133 boys, 149 girls) of the 556 childre icluded i the Dutch Study of Epilepsy i Childhood. The media period betwee the first seizure ad obtaiig this blood sample was 69 days (rage days-6 years). No sigificat differeces were foud i sex, aetiology ad epilepsy sydrome distributio betwee the childre from whom a blood sample was take ad the childre from whom o blood

3 146 P. M. C. Callebach et al. sample was take. Childre from whom o blood sample was obtaied at itake ( = 274) had a sigificatly lower age at the oset of their epilepsy tha childre from whom a blood sample was obtaied at itake ( = 282; media age at oset 5 1 ad 6 1 years, respectively; P < 5). Of the 282 childre i our cohort, 164 (58%) suffered from seizures of idiopathic aetiology, 44 (16%) from seizures of cryptogeic aetiology ad 74 (26%) from seizures of remote symptomatic aetiology (Table 1). Twety-eight childre i our cohort experieced a sigle, uprovoked seizure. Epilepsy sydrome distributio differed sigificatly betwee the three groups (P < 1): childre with epilepsy of idiopathic aetiology suffered relatively more ofte from geeralized epilepsy ad less from localizatio-related epilepsy tha the other two groups, ad childre with epilepsy of cryptogeic aetiology suffered relatively less frequetly from geeralized epilepsy tha childre with epilepsy of remote symptomatic aetiology (P < 1, Table 1). Furthermore, outcome differed sigificatly betwee the three groups (P < 1): childre with idiopathic aetiology had a sigificatly better outcome tha both childre with cryptogeic aetiology ad childre with remote symptomatic aetiology (P < 1, data ot show). Immuoglobuli levels at itake At itake, levels of IgA, IgG1, IgG2 ad IgG4 were sigificatly higher i our cohort of 282 childre tha the reported media Ig (sub)class levels of healthy childre of the correspodig ages (the ratios were sigificatly higher tha 1, P < 1, Fig. 1). Sixty-three childre (22%) had a IgG1 cocetratio above the upper limit of the ormal rage for the correspodig age. For the other Ig (sub)classes, up to 6% of the childre had cocetratios below the lower limit, ad up to 9% had cocetratios above the upper limit of the ormal rage. The umbers of childre with a serum cocetratio outside the ormal rage were: for IgM, 16 below the lower limit ad 11 above the upper limit; for IgA, 18 ad 18; for IgG2, 8 ad 26; for IgG3, 1 ad ; ad for IgG4, 3 ad 13, respectively (Fig. 1, grey areas). Two childre had a absolute IgA deficiecy, ad oe other child a absolute IgG3 deficiecy. Aetiology (i.e. idiopathic, remote symptomatic, cryptogeic), epilepsy sydrome distributio (i.e. localizatio-related, geeralized, sigle seizure), age at itake ad outcome were ot sigificatly differet betwee childre with Ig cocetratios below the lower limit or above the upper limit of the ormal rage ad those with Ig cocetratios withi the ormal rage. This observatio holds for all Table 1. Cliical characteristics of the childre from whom a blood sample was take at itake ( = 282) Idiopathic Cryptogeic Remote symptomatic Total Number (%) 164 (58 2) 44 ( 6) 74 (26 2) 282 (1 ) Media age at takig blood sample (year) Distributio of epilepsy sydromes a Localizatio-related (%) 22 (13 4) b 41 (93 2) 39 (52 7) 12 (36 2) Geeralized (%) 114 (69 5) 3 (6 8) 31 (41 9) 148 (52 5) Other (%) 3 (1 8) 1 (1 4) 4 (1 4) Sigle seizure (%) 25 ( 2) 3 (4 1) 28 (9 9) a Distributio accordig to the revised classificatio of the Iteratioal League Agaist Epilepsy, 1989 [21]. b Epilepsy sydrome distributio differed sigificatly betwee groups (P < 1) IgM IgA IgG1 IgG2 IgG3 IgG * 1. 3* 1. 13* * ( ) ( ) ( ) ( ) ( ) ( ) > > > Ratio Fig. 1. Ratio betwee the observed immuoglobuli (Ig) (sub)class cocetratios i childre from whom a blood sample was obtaied at itake ( = 282) ad the published media of ormal levels [24,25]. IgA, IgG1, IgG2 ad IgG4 cocetratios were sigificatly higher i our cohort tha the reported media Ig (sub)class cocetratios of healthy childre of the correspodig ages (*P < 1). Grey areas represet childre with Ig (sub)class cocetratios below the lower limit or above the upper limit of the ormal rage. The media ratio of all Ig (sub)classes as well as the rage (betwee brackets) are give. >: ratio 3 4.

4 Immuoglobulis i childre with epilepsy 147 (sub)classes with oe exceptio. Childre with a IgG1 cocetratio above the upper limit of the ormal rage were sigificatly youger tha childre with a IgG1 cocetratio withi the ormal rage (media age at itake 4 5 ad 6 9 years, respectively, P < 1). At the time of the first blood samplig the seizure frequecy was kow i 163 of the 282 patiets. Ig levels did ot differ sigificatly betwee childre who had experieced a sigle seizure ad those who had multiple seizures. However, there was a sigificat egative correlatio betwee the overall seizure frequecy ad the IgG1 level corrected for age (P = 3), idicatig that IgG1 was lower i childre with higher seizure frequecy. For the other Ig (sub)classes o sigificat correlatios were foud. No sigificat differeces i Ig were observed betwee the differet epilepsy sydromes as classified by the ILAE (icludig six childre with West sydrome ad two with Leox Gastaut sydrome) [21]. I our cotrol group of 76 healthy childre, who were boe marrow trasplat doors, oe of the media cocetratios of the Ig classes ad IgG subclasses were sigificatly differet from those reported i healthy childre of the correspodig age group. O a idividual basis, abormal cocetratios of oe or more of the Ig classes ad IgG subclasses were detected oly i sporadic cases, ad oly 5% of the childre i our cotrol group showed a icrease of IgG1 (data ot show). Immuoglobuli levels after usig ati-epileptic drugs for 9 18 moths I 127 (45%) of the 282 childre, a secod blood sample was obtaied after 9 18 moths of cotiuous AEDs use. Media age at oset of epilepsy, sex, aetiology, distributio of epilepsy sydromes ad media Ig ratios at itake did ot differ sigificatly betwee these childre ad those from whom o secod blood sample was take. After usig AEDs for 9 18 moths, IgA (P < 1) ad IgG4 (P < 1) levels had decreased sigificatly compared to the levels at itake; IgG1 (P < 1) ad IgG3 (P < 1) levels had sigificatly icreased (Fig. 2). The sigificat decrease i IgA ad IgG4 levels led to ormalizatio of these levels with a media ratio of approximately 1; there was o differece i the umber of childre with IgA or IgG4 cocetratios below the lower limit of the ormal rage at itake ad after AEDs use for 9 18 moths. No ew cases with a absolute IgA deficiecy were observed. The sigificat icrease of IgG1 after 9 18 moths of AEDs use, however, led to 38% of the 127 childre havig a IgG1 cocetratio above the upper limit of the ormal rage (Fig. 2), which was sigificatly more tha before treatmet (24%, P < 1). The chage i IgG1 levels over time did ot differ sigificatly betwee differet aetiologies or differet outcomes. Childre with geeralized epilepsy, however, showed a sigificat icrease of the IgG1 level (P < 1) while the At itake 3 IgM IgA IgG1 IgG2 IgG3 IgG ( ) ( ) ( ) ( ) ( ) ( ) > > > After 9 18 moths. 95. * * **. 94 * 3 ( ) ( ) ( ) ( ) ( ) ( ) > > > > Ratio Fig. 2. Ratio betwee the observed immuoglobuli (Ig) (sub)class cocetratios i childre ( = 127) from whom a blood sample was obtaied at itake (upper pael) ad after 9 18 moths of AEDs use (lower pael), ad the reported media of ormal levels [24,25]. IgA (*P < 1 ad IgG4 (**P < 1) levels had decreased sigificatly as compared to the levels at itake; IgG1 (*P < 1) ad IgG3 (**P < 1) levels showed a sigificat icrease. Grey areas represet childre with Ig (sub)class cocetratios below the lower limit or above the upper limit of the ormal rage. The media ratio of all Ig (sub)classes as well as the rage (betwee brackets) are give. >: ratio 3 4.

5 148 P. M. C. Callebach et al. media IgG1 level remaied approximately the same i childre with localizatio-related epilepsy. Furthermore, aetiology, outcome ad epilepsy sydrome distributio were ot sigificatly differet betwee childre with a IgG1 cocetratio above the upper limit of the ormal rage ad childre with a IgG1 cocetratio withi the ormal rage. The age at the time of the secod blood sample was, however, sigificatly lower i childre with a IgG1 cocetratio above the upper limit of the ormal rage tha i childre with a IgG1 cocetratio withi the ormal rage (media age 4 3 ad 9 5 years, respectively, P < 1). The icrease of IgG3 led to 2% of the childre havig a IgG3 cocetratio above the upper limit of the ormal rage after 9 18 moths of AEDs use (Fig. 2). Ati-epileptic drugs To determie more closely the ifluece of distict ati-epileptic drugs, chages of Ig cocetratios i childre that used carbamazepie or valproic acid as mootherapy were ivestigated. After 9 18 moths, 34 (27%) childre had cotiuously received carbamazepie mootherapy ad 6 (47%) valproic acid mootherapy. Of the other 33 childre, seve used ethosuximide, two vigabatri, oe pheytoi ad 23 had polytherapy. Because of the small size of the groups, the ifluece of these ati-epileptic drugs o the immuoglobulis could ot be determied. Of the 34 childre usig carbamazepie, seve (21%) suffered from epilepsy of idiopathic aetiology, 13 (38%) from epilepsy of cryptogeic aetiology ad 14 (41%) from epilepsy of remote symptomatic aetiology. Thirty-oe (91%) had localizatio-related epilepsy ad three (9%) geeralized epilepsy. I childre o carbamazepie mootherapy, IgA (P < 1) ad IgG4 (P < 1) levels had decreased sigificatly over time, leadig to ormalizatio of the media IgA ad IgG4 levels (Fig. 3a). Of the 6 childre usig valproic acid, 44 (73%) suffered from epilepsy of idiopathic aetiology, three (5%) from epilepsy of cryptogeic aetiology ad 13 (22%) from epilepsy of remote symptomatic aetiology. Seve (12%) had localizatio-related epilepsy ad 52 (87%) geeralized epilepsy. I childre o valproic acid mootherapy, IgA levels showed a sigificat decrease to ormal cocetratios with a media ratio of approximately 1 (P < 1) ad a sigificat icrease of IgG1 levels (P < 1, Fig. 3b). After 9 18 moths of treatmet, 26 (43%) of these childre had a IgG1 above the upper limit of the ormal rage compared to 18 (3%) at itake. This differece was ot statistically sigificat. To ivestigate whether the observed icrease i IgG1 was due merely to the use of valproic acid, it was tested whether IgG1 levels decreased after discotiuatio of valproic acid. Blood samples were take from 1 childre who were excluded from the aalysis described above because they discotiued AEDs withi 9 moths, just before discotiuatio of valproic acid ad 4 11 moths after discotiuatio. IgG1 levels sigificatly decreased after discotiuatio of valproic acid (P < 5, data ot show). Furthermore, we ivestigated whether IgG1 levels differed betwee childre that had polytherapy with ( = 18) or without ( = 5) valproic acid. These groups did ot differ sigificatly i age, aetiology, epilepsy sydrome distributio, outcome ad IgG1 levels at itake. After usig therapy for 9 18 moths, however, IgG1 levels were sigificatly higher i the group that used polytherapy with valproic acid tha i the group without valproic acid (P < 5, data ot show). Whe comparig Ig levels betwee childre usig carbamazepie ad childre usig valproic acid, it was observed that IgM levels were sigificatly lower i the group usig carbamazepie tha i the group usig valproic acid (P < 1). Furthermore, IgG1 levels were sigificatly higher i the group usig valproic acid tha i the group usig carbamazepie (P < 1). The other Ig levels did ot differ sigificatly betwee the two groups. DISCUSSION This study focuses o a large cohort of childre with oe or more uprovoked epileptic seizures followed prospectively from their first visit to a specialist cliic. Serum samples were already available early after the first presetatio with seizures ad before the iitiatio of ay treatmet with AEDs. I additio, a secod serum sample was available i about half of the patiets at followup after 9 18 moths of AEDs use. Sice media cocetratios of the Ig (sub)classes i serum samples of our cotrol group of 76 healthy childre were ot sigificatly differet from the reported media values i healthy age-matched cotrols [24,25], our experimetal approach ca be cosidered to be valid. Therefore, the observed icrease i the media serum cocetratio of IgA, IgG1, IgG2 ad IgG4 (corrected for age) i our cohort of childre with ewly diagosed epilepsy idicates that disturbaces of humoral immuity are already preset before the iitiatio of medical treatmet, ad that these disturbaces are idepedet from aetiology ad the type of epilepsy sydrome. However, icreased IgG1 cocetratios were especially detected i youg childre. It has to be realized that the childre from whom o blood sample was take at itake were sigificatly youger tha the childre from whom this blood sample was obtaied. Therefore, the ifluece of epilepsy o IgG1 might be uderestimated because of a samplig bias. To our kowledge, this is the first study i which oly childre are erolled ad i which serum Ig cocetratios were already measured withi a short period (media: 69 days) after the first presetatio with epileptic seizures ad before the start of AEDs. Some other reports have also described alteratios of humoral immuity i epilepsy patiets who were ot o AEDs [13,], whereas Leti et al. did ot observe alteratios i utreated patiets [26]. Ufortuately, the time period passed betwee the first presetatio of seizures ad the measuremet of serum Ig cocetratios was ot idicated i these papers. The uderlyig mechaism for the observed disturbaces of humoral immuity i childre at a early stage of epilepsy remais ukow. Oe ca speculate that ifectios might have triggered the immue respose, as suggested by the icreased serum cocetratios of various IgG subclasses ad IgA, ad cocomitatly might have caused a disturbace of the blood brai barrier. Exposure of formerly hidde atiges of the CNS to the immue system might lead cosequetly to seizures possibly mediated by cross-reactive autoatibodies produced i respose to the ifectious agets or by atibodies iduced by atiges of the CNS itself. However, i our study cohort there is o formal idicatio for such a order of evets. At itake, each of the 282 childre showed ormal leucocyte couts ad a ormal leucocyte differetiatio, suggestig that ifectios i this populatio at that time poit were very rare. O the other had, 5 3% of the childre i our study cohort showed a icreased serum cocetratio of IgD at itake, i compariso with oe of the childre i the cotrol group (data ot show). At the Departmet of Paediatrics of the Leide Uiversity Medical Cetre, elevated levels of IgD are particularly detected i childre sufferig from

6 Immuoglobulis i childre with epilepsy 149 (a) IgM IgA IgG1 IgG2 IgG3 IgG4 Carbamazepie group at itake ( ) (.1 3.1) ( ) ( ) ( ) (.9 1.5) > Carbamazepie group after 9 18 moths ** * (.3 1.6) (.1 3.8) ( ) ( ) ( ) (. 8.) > > > Ratio (b) IgM IgA IgG1 IgG2 IgG3 IgG4 Valproic acid group at itake (.3 2.4) (.5 3.9) ( ) ( ) (.41 3.) ( ) > > > Valproic acid group after 9 18 moths ** 1.63 * (.3 3.) ( ) ( ) ( ) ( ) (.5 8.2) > > > Ratio Fig. 3. Ratio betwee the observed immuoglobuli (Ig) (sub)class cocetratios at itake (upper pael) ad after 9 18 moths (lower pael) of (a) carbamazepie ( = 34) or (b) valproic acid ( = 6) mootherapy, ad the reported ormal levels [24,25]. I childre usig carbamazepie, IgA ad IgG4 levels showed a sigificat decrease (**P < 1). The childre that used valproic acid had a sigificat decrease of IgA levels (**P < 1) ad a sigificat icrease of IgG1 levels (*P < 1). Grey areas represet childre with Ig (sub)class cocetratios below the lower limit or above the upper limit of the ormal rage. The media ratio of all Ig (sub)classes as well as the rage (betwee brackets) are give. >: ratio 3 4.

7 P. M. C. Callebach et al. recurret respiratory tract ifectios or autoimmue diseases (e.g. juveile idiopathic arthritis). We did ot fid a correlatio betwee a icrease of IgG1 ad a elevatio of IgD i our cohort. Because o cliical iformatio about the presece of, e.g. respiratory ifectios was obtaied at itake, o statemet ca be made about the relatio betwee ifectios ad epilepsy i our cohort. As a first step to ivestigate the possible aetiology of the various forms of childhood epilepsy more closely, it will be relevat to measure atibody titres i these sera agaist bacterial ad viral micro orgaisms ad agaist a pael of autoatiges. The lack of a associatio betwee the occurrece of abormally low or high cocetratios of serum Ig classes or IgG subclasses early i the disease ad the outcome (termial remissio) of the epilepsy measured 5 years after itake, idicates that Ig levels before the start of AEDs treatmet are ot useful as markers for the early recogitio of patiets with itractable epilepsy. Ig cocetratios at the time of the secod blood samplig were also ot sigificatly differet i childre with differet outcomes. The decrease of IgA ad IgG4 ad icrease of IgG1 ad IgG3 after 9 18 moths of AEDs treatmet i the whole study populatio of 127 childre ca, at least partially, probably be attributed to the effect of medicatio. I childre o carbamazepie mootherapy for 9 18 moths, IgA ad IgG4 cocetratios showed a decrease i compariso with the level before the iitiatio of treatmet. Regardig the decrease of IgA, our observatio is i lie with a earlier report cocerig adults o carbamazepie [1]. However, i our study cohort we did ot fid a sigificat decrease of IgM as reported previously by others i adults [1] ad childre [13]. Furthermore, our data are cotradictory to other reports i adults [12] ad childre [26], which showed o effect of carbamazepie treatmet o serum cocetratios of ay of the major Ig isotypes. I a combied populatio of adults ad childre, Gilhus ad Lea have described a associatio betwee carbamazepie mootherapy ad a decrease of IgG2, while IgG4 remaied uaffected [11]. Iterpretatio of the divergece of these observatios from our results is impossible, due to the lack of data obtaied before the start of treatmet i most of the studies, the variable compositio of the study populatio regardig aetiology ad type of epilepsy sydromes, the usually small size of the study groups ad the variable duratio of medicatio use ragig from moths to over 1 years. Moreover, iformatio o the start of medicatio related to the oset of epilepsy is ot available from most of the published studies. Our results idicate that valproic acid, as mootherapy or as part of a combied therapy, is associated with a icrease of IgG1. I additio, i childre o mootherapy with valproic acid, IgA decreased to ormal levels. Data i the literature o the effect of valproic acid o the cocetratio of serum Ig classes are scarce ad eve lackig whe IgG subclasses are cocered [14 16,26,27]. Although the same costraits hold for these studies as idicated above for the studies o carbamazepie, the commo observatio arose i these studies that the cocetratios of the major Ig isotypes i serum are uaffected i patiets treated with valproic acid. Ufortuately, we have o iformatio about the chage i serum immuoglobuli cocetratios over time i o-treated patiets with epilepsy. Therefore, we caot exclude that the observed chages are caused predomiatly by the epilepsy itself ad ot by the use of AEDs. We observed, however, that IgG1 levels decreased sigificatly after withdrawal of valproic acid, leadig to the coclusio that valproic acid was ideed resposible for the icrease of IgG1. It is attractive to speculate that the diverget developmet of Ig (sub)class cocetratio i childre treated with carbamazepie ad valproic acid, respectively, might be associated with a differet effect of these AEDs o B cell maturatio (i.e. Ig isotype switchig), either directly at the B cell level or at the level of regulatory T lymphocytes. I coclusio, humoral immuity is already altered i childre early after the first presetatio with epileptic seizures. Whether this is the cosequece of a exogeous evet, such as the occurrece of ifectio, ad to what extet this is related to a iteractio of the CNS ad the immue system remais to be evaluated. Treatmet with carbamazepie ad valproic acid is associated with sigificat chages of serum cocetratios of distict Ig isotypes ad IgG subclasses. 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