Critical role of HLA typing and immunomonitoring in successful transplantation

Transcription

1 Critical role of HLA typing and immunomonitoring in successful transplantation Vali Kermaniarab,PhD, ASCP, D. (ABMLI) Scientific Director and clinical consultant

2 Successful surgical step in transplantation is often adversely challenged by action of; Complex interaction of the immune system to trigger extensive inflammatory condition and diseases including : thrombosis, fib rosis, collagen deposition, hypertension, metabolic disorders, tissue injury, HVG and GVH, etc. Environmental /Epigenetics factors: - Therapeutics Medications /Immuno suppressive agents - Infectious diseases - Stress factors i.e. reactive oxygen species (ROS),ischemia Detail understanding of system biology and application modern technology facilitate maintenance of healthy and enhancing life after transplantation.

3 Paradigm of transplantation Transplantation as a ultimate treatment for terminal disease Robust immune response leading to adverse inflammatory diseases: HVG rejection, GVH, autoimmunity's, immunodeficiency's, infectious, malignancies, CNS, Hyper-sensitivities, CVS, GI, metabolic, respiratory, renal, fibrosis, thrombotic, hyper - tension, genomic alteration, etc. Drug induced toxicity and carcinogenesis : - Calcineurn inhibitors metabolize by CYP3A4, CYP3A5 and CYP3A5 3 but CYPA4*1 / CYP3A5*1 & CYP3A4*1 B/CYP3A5*1 elicit renal toxicity - Calcineurin inhibitors enter into the cells via glycoprotein pump encoded by ABCB1 gene to block calcineurin phosphatase via immunophillin to inhibit NFAT translocation to DNA to inhibit Il-2 production to prevent T and B lymphocytes proliferation, result in serious pan immunodeficiency, high susceptibility to succumb to infectious agents - Calcineurin inhibitors exert negative regulatory role on P53 to promote carcinogenesis eg, keratinocyte s malignancy is common in post transplantation receiving calcineurin inhibitors * *ref.: Cancer research volume 71issu6, 2011

4 Highlights in life enhancing after transplantation Recognition and evaluation of physiological conditions of donor/ recipient Analysis donor s/recipient s status, ABO and HLA, non HLA typing of donor/ recipient to select a best match Comprehensive and frequent immunological evaluation (innate and adaptive) during pre - and post- transplantation. Searching for Infectious agent(s ). Pharmacogenomics studies and drug monitoring for high therapeutic/ minimal toxicity /side effect Promote specific immune regulation and tolerance induction

5 Non-classical class I are HLA-G ( protect fetus from maternal immune response), HLA-E ( present peptide to NK receptor) HLA-F. MICA encode ligand for NKG2D r activation( 70 MICA.& over 30 MICB). Strongest determinants are HLA-DR followed by HLA-B, then HLA-A as a target. HLA-DR, -DQ,-DP, -DM,- DO generate peptides for HLA-A class I formation. Class III encode C2,C4, factor B, TNFα, lymphotoxin α,β, 21 hydroxylase, heat shock proteins. DRB2, DRB6, DRB7, DRB8, DRB9, DPB2,DQA2, DQB2, DQB33 are pseudo genes The Major Histocompatibility Complex Short arm MICA, B

6 Polymorphism of HLA Class I and Class II Molecules The MHC region is one of the most polymorphic regions of the human genome polymorphism is focused around the peptide binding region Top view of MHC The MHC region is one of the most polymorphic regions of the human genome

7 MHC Class I polymorphism Number of alleles/proteins Alleles Proteins A B C E F G

8 MHC Class II polymorphism Number of alleles/proteins Alleles Proteins a b a1 b1 a1 b1 DR DQ DP

9 MHC polymorphism: is an important basis for allograft rejection Opelz G. et. al., Transplantation MM refers to matching for HLA-A, -B, and DR only

10 Cross reactive Groups of Ags (CREGS) induced cross reactive immune response A cross reactive group of HLA Ag is defined by the reaction pattern of an antiserum that reacts with multiple Ags even thought it was, in fact, produced in response to a single Ag. ( sharing public antigenic determinant, epitope ) for example the Abs in pregnancy serum was produced from immunization by a single private Ag of the paternal haplo - types of the baby, for example B7. However the serum will also react with Ags B27,55,56,60 and 61.these Ags are considered to be members of the B7 CREG. Patients with high titers of antibodies against HLA Ag are frequently found to have made Abs against only one or two CREG Ag rather than against multiple private HLA Ag.

11 Generation of DSA A1, 24; B8 Recipient Donor kidney A1,2 B B77,8 Immune response to donor antigen Anti-A2 + Anti-B7

12 Generation of DSA DSA are rarely generated alone and generally antibodies to HLA molecules related to the donor HLA are also often found: A68 A23 A1,24; B8 A1,2 B 7,8 Anti A2 A28 A69 A24 B57 B58 + B41 B42 Anti B7 B55 B13 B27 B60 B61 B54 B48 B47 Due to shared epitopes with donor HLA

13 Current HLA matching for solid organ Recipient and donor are HLA typed at low resolution: HLA-A HLA-B HLA-C DRb1 DRb3,4,5 DQb1 DPb1 Recipient 1, 2 7, 8 1, 6 4, 17 52, 53 2, 8 1, 4 Donor 1, 2 8, 27 1, 6 1, 17 51, 52 2, 8 2, 6 3 Antigen Mismatch (3MM) has current chance of survival after 5 years is 68.5% 1 class I mismatch + 2 class II mismatches * DP is not currently typed% The problem : It is very difficult to find 0MM donors using current HLA matching strategy, but some mismatched transplants succeed long time if tolerance develop to other antigens

14 Consequences of sensitization Patients awaiting transplantation, who have Abs against HLA Ags either currently or in past, will have greater difficulty in finding a compatible organ donor than will un sensitized patients. Compared with unsensitized patient sensitized patient wait longer for transplantation and are at greater risk for rejection episodes when they do receive a graft.

15 Immunological response /Sensitization as a critical factor in graft failure Mismatch HLA antigens particularly HLA -A, -B, - DR are highly immunogenic. However, immunogenicity of other polymorphic HLA and non- HLA types can not be ignored, e.g. Kidney transplant failure has been reported in certain cases of perfect HLA-A, HLA-B, HLADR match & MICA mismatch Crucial immunological response to non-self antigen can be encountered through humeral,and cellular activities: Blood transfusion, IgG, IgM antibodies Transplantation, IgG antibodies Pregnancy, IgG antibodies Vaccination Microbial agents with cross reactive epitopes Epigenetics factors transcriptional factors mode / binding chromatin remodeling insertion, deletion

16 Panel Reactive Antibody Panel Reactive Antibody (PRA) is an immunological laboratory test routinely performed on the serum of people awaiting organ transplantation. The PRA score is expressed as a percentage between 0% and 99%. It represents the proportion of a given population to which the person being tested will react via pre-existing Abs. These Abs target the HLA. Each population will have a different demographic of HLA, and so the PRA test will differ from country to country.

17 Frequency of PRA testing Pre transplant - to screen patients for PRA in specified intervals. This should not be more than 3 months. In case of blood transfusion, a sample should be sent to the laboratory between 14 to 28 days post transfusion. If PRA and antibody specificity are determined on a of patient serum, this can greatly help in predicting the cross match results. Even in patient who receive zero mismatches at HLA-A, B and DR benefit from regular screening and other antibodies characterization. Anti-HLA antibodies vary with time in one individual Therefore, it is recommended to repeat testing for PRA at different intervals Antibody specific to HLA Cw, DQ, and even DP, as well as anti MICA have been shown to influence graft survival outcome

18 Antibodies relevant to transplantation / function Anti HLA (A,B,C,DR,DP,DQ ) Abs on endothelial /acute/ chronic renal rejection: Increase Von Willibrand factor (VWF), externalized P-selecting which, increase activation and trafficking of platelet and leukocytes, result in tubular thrombosis, necrosis, glomerulonephritis and loss of kidney function Anti MICA/ MICB antibodies: MIC Ag. express on epithelial (i.e GI ), fibroblast, D.C, monocytes, endothelial cells and only on stressed lymphoid cells. Antibodies to MIC Ags. Play critical role in in organ i.e., renal rejection Anti-vascular endothelial cell (VEC): Some studies have suggested a role of VEC / HPA Abs in increasing risk for graft loss but this finding has not been widely confirmed. Anti-angiotensin type I receptor (AT1R) antibodies: AT1R bind angiotensin II ligand to regulate arterial blood pressure and water / salt inbalance. AT1R antibodies alter arterial blood pressure, water /salt balance result in malignant hypertension Other non- HLA antibodies i.e. HY Peptide from Y chromosome, HA1 to HA5 from minor HLA ( HA1, HLA2 only leukocytes), human platelet alloantigen (HPA) Autoantibodies: These non-specific antibodies are benign to transplant but can cause false positive reactions in the donor cross match test.

19 Humeral & Cellular immune response to non-self antigen / protection vs injury non-self-antigen or pathogen ( process by phagosome ) Adaptive GSK3β innate Procaspase caspase ProIL-1β, ProIL-18β Treg cell IL-1β, IL-18β B cell IL-23 induce Th17 IL-10 Activate NFkB IL- 6 COPD induce Th1 Th2 TNF-α IL-4 NK IL-12 Inflammation chronic inflammation TGF-β EMT Ab + C tissue injury Tissue repair inflammatory diseases ADCC fibrin formation, collagen dep.,necrosis fibrosis

20 Ag. Involvement of both arms of immune system in graft rejection TNFα,IL-6 MACRO TGFβ NFkB MHC-2 /Ag MHC-1/ag Fibrosis IL-1,IL-12 inflammation MAC, Th2 CD4 IL-2 B complement MICA, Alloantigen CD8 Ab NKG2D, KIR C3a,C5a/ attract NK Ag leukocytes into tissue Soliris (eculizuumab) CDC IgG1,IgG3 strongest CDC Il-2,TNF,IFNγ IgG2,IgG4 ADCC inflammation Acute or chronic graft rejection Act. Mast,eos/ PAF, protease,il-3, IL-5 GMCSF,LTC, / vascular thrombosis, Acute /chronic injury th1 th2 TLR-2,IL-4 Activate mast recruit neu, eos Steroid resistant graft rejection DC TLR2 Il-17, ccl-2,cxcc-2,,cxcl-5,ll-18, recruit eos, neutrophil strong rejection th17

21 Activation of T helper cells by class I or II HLA facilitate other immune cells response T cell via class II or Class I HLA molecules differentiates or help to induce APC MAC HLAI CD8 naive IL-12 HLAII IL-1 TH1 CD4 naive CD40 L IL-4,TLR2 TH2 IL4,-5,-9,-10,-13 HLAII, HLAI, MICA CD40 B cell naïve IgM,IgD,CD19 TC1 TC2 IL-2, IFN-ϒ, TNF-α Memory B cell Act. B TGFβ Il-6, TGFβ, IL-21 IL17,-21, CCL-2, recruit leukocyte IL4,IL5, IL10 CD4 naive th17 MAC IL-10,4,9,13, TGFβ,FoxP3 IL-33 NK treg th3 th2 IL-10, TGFβ plasma cell Antibody

22 Role of Th2 in immune regulation and hypersensitivity formation and tissue damage, organ failure NK CD4 DC TLR2 Treg IL-4 TH2 IL-4 NK IL-10,-21,TGF-β IL-17 induce CCL-2, materix metanoloproteinase-12 to recruit & activate neutrophil & eosinophil IL-5,-3,GMCSF Th-17 IL-17 NK Eosinophil B cell IL-4,IL-6,IL-13 Mast cell Immunoglobulin Class switching LTC4,. Histamine, PGD2 Organ collagen deposition Capillary clot formation Graft i.e., kidney rejection Serve as APC INITIATE Ag. Specific immune response. PAF, LTC4, toxic basic protein, Cathepsin, peroxidase, lysozyme, Cell death, thrombosis, acute/chronic renal graft rejection

23 TTT

24 Role of NK cell in early and long lasting chain of immune response to allograft NK cell is license to Kill allograft, tumor or infected target Induce anergy/tolerance Directly indirectly Directly indirectly contact ADCC (IgG2,IgG4Ab), inflammation via NK cytokine /chemokine NK / target anti allo-ag NK activate inhib. KIR NK produce IL-4 perforin/ bind to NK FCγRIII Th1/ macrophage to generate Th2, granzyme B via IFNϒ produce IL-10 NK leukocytes recruit. To down regulate via CCL3,CCL4,CCL5 immune response IgG anti allo ag FCϒRIII Th2 via IL-4 to TGFβ from treg or isotype switch macrophage Target and enhance Ab pro., inhibit NK activity allo ag & recruit /activate leukocytes, platelet TLR class 1 Or class 2 mismatch activate via act KIR, Whereas MICA allo antigen activate NK via NKG2D

25 Biological Role of Cytokines, Chemokine's associated with NK cells Cytokines / chemokines produce by NK : IFNγ : Inhibit Th2, enhances proliferation of activated B cells IL-17A: Regulates local tissue inflammation IL-22; Regulates production of acute phase protein TNFα : Pro-inflammatory molecules,involved in regulation of cell survival MIP-1α (CCL3) : Recruit leukocytes i.e.,cd8 +T cell to stimulate antigen specific response MIP-1ß ( CCL4) : Recruit leukocytes i.e.,cd4+t cell to promote B cell to specific antibody RANTES (CCL5):Recruit innate leukocyte certain cell proliferation i.e. eos, IL-4 : Activate Th-2 Cytokines/ Chemokines role in maturation, stimulation of NK cells: E4BP4 (maturation / activation),il-12 (activation / stimulation / cytotoxicity/ IFNγ,TNFα), IL-15/1L-15R (proliferation/accumulation/survival ), IL-18 ( upregulate cytotoxicity )

26 Humeral and cellular immune factors involvement in graft rejection. - Cellular: Humeral :. CD3+HLADR+, perforin, granzyme B. Th1,Th2, Th17, CD4+CD25+FOXP3+ BAFF. CD8+ (perforin, granzme B) C1q,C1s,C4a,C4b,CD4d,C2a,C2b,. CD19+CD27+IgD+ Hi ( naïve B cell ) C3a, C3b, C4b2a, C3a,Ceb,MAC. CD19+IgD Lo, CD38 Lo, CD27+ ( memory B cell) C3d. CD56 bight, CD16 dim, CD56 dim CD16 bright DSA, anti MICA Ab, ATR Ab.. In Chronic. GVHD: naïve B cells low, but B cell receptor (BCR)-activated CD27 high #,. BAFF / B cells ratio increase, CD27+ CD38+ Hi, IgD Lo ( plasma cell ).. Monocyte: CD14,CD16. mdc : BDCA-2, BDCA3, BDCA4, PDC: BDA-2, BDCA4, CD11C, CD123 bright, (associated with acute GVHD ).. BASO.EOS. NEUT - Inflammatory factors,cytokine,chemokine, growth factor: IL-1β, IL12, IL-6,,CRP, IL-8,TNFα, TNFß, smooth muscle growth factor, IL-2, IFNγ, GM CSF,IL-3, PAF, IL-4, IL-5,IL-10 IL-2,,IL-21, IL- 23,TGFß, IL-17, IL-8, MCP- 1, (CCL2) IL-8, CCL-3 CCL-4,CCL-5, methanoproteinase-12,,baff CXCL10,CCL13,CCL17,CXCL13,

27 Robust secondary allo-stimulation - Secondary allo-stimulation of the memory response from : Re-exposure to same HLA Ag Exposure to cross-reactive HLA Ag, public antigenic determinant Exposure to cross-reactive microbial Ag Exposure to polyclonal mutagens ;certain types of viruses Nephrectomy of a failed graft. - Secondary response involve memory rather than naive cells : Relatively more resistance to immunosuppressive drugs Quicker response and more abundant antibodies Higher affinity antibodies Quicker and more cellular response

28 - Low immunological risk.cross match is ( - ), not sensitized,igg anti HLA (- ) or IgM only, or antibody to such as non-hla i.e., autoantibody..cross match positive but not donor specific, or patient is not sensitized. Basis of Successful Transplantation /risk factors Recognition of Individual s System Biology and Environmental Factors Finding good match ( HLA, null, KIR, MICA, HA, HY, blood group, typing / Ab., Donor specific antibodies (DSA ), inflammatory markers, infectious agent(s), pharmacogenetics, general patient s condition) ; - Anti bodies result in immunological risk at post transplantation: - High immunological risk / hyper acute rejection (minute to days). Panel reactive antibodies (extend of patient s sensitization) > 85% (highly sensitive and highly at risk.). Patients with anti- HLA, -ABO, - endothelial. Complement activation trigger CDC which can be assessed by circulatory C3d detection. Complement by products (C3a, C5a)recruit leukocyte,which infiltrate into tissue, result in micro-thrombi and necrosis - Intermediate risk. positive cross match by flow cytometry (weak IgG, IgM donor specific anti HLA on B cell ), ADCC activity, but in absence or presence of CDC. Cross match B cells, positive for weak IgG anti HLA antibodies depen dent cytotoxicity for current and historical sample.

29 Chronic allograft nephropathy (CAN) CAN is characterized by tubular atrophy, interstitial fibrosis and glomerular lesions Underlying mechanisms in CAN formation ; - Acute and/or chronic Immune response - Donor condition,age, health status - Donor /recipient size disparity - Ischemia leads up regulation of HLA antigen, adhesion molecules and cytokines. - Perfusion,the resupply of blood to organ that has been deprived of oxygen triggers reactive oxygen species (ROS) formation which, result in tissue injury - Hypertension - Hypersensitivity - Diabetes - Drug toxicity - Infection - Hyperlipidemia

30 Benefit of immune, inhibition unresponsiveness / tolerance induction Factors inducing unresponsiveness : - Cellular interaction, failure of T cell or T cell help for B cell to respond, CD 40L / CD 40. Complement ( anti complement Ab. ) - Immune regulatory cell or regulatory products - Physical nature of antigens / low dose antigens. Membrane bound or particulate antigens, the self reactive B cell dies, a phenomenon refer to clonal deletion. Soluble protein antigen, which presumably generate weaker signals through the B cell receptor ( BCR ) of self reactive B cell, do not cause cell death but instead make the cell unresponsive a phenomenon called Anergic B cell - Chimerism - Anti idiotype antibodies - MicroRNA ( e.g.,mir-23b inhibit Th-17 )

31 Assessment of anti HLA antibodies Complement dependent cytotoxicity (CDC) CDC was the first technique which used to detect HLA specific antibodies. It employs the use of live lymphocytes to detect lymphocyte specific antibodies by activation of complement system and killing of lymphocytes. However, this technique has recently been replaced by more advance and reliable method due to it s draw- backs, such as : - It is limited by the cell panel used, - It depends on the quality of lymphocytes and rabbit complement, - May detects non-hla antigens and it only detects complement fixing anti bodies. - Subject to anti complementary factors In solution - Target cells can be killed non-specifically prior or during analysis - Results are expressed as percentage of cells which reacted with the tested sera - Therefore, patients cannot be tagged as sensitized on the basis of this test.

32 Assessment of anti HLA antibodies by solid phase immunoassay ( enzyme-linked immunosorbent assay ) The enzyme-linked immunosorbent assay (ELISA) employs the use of purified HLA antigens independent of complement and live cells. This excludes the non-hla specific antibodies. There are two types of commercially available kits, one detects presence or absence of PRA. the other detects antibody specificity. ELISA offer higher sensitive than the CDC assay, however, ELISA exhibit following limitations : - Antigen variability's ( amounts, condition) - interference ( external: IVIg, thymoglobulin) - Interference ( intrinsic: autoantibodies, hi IgM, IgG anti IgM, immunocomplexes) - Insensitivities to Low level of anti bodies - Non-specific UV absorption

33 Assessment of anti HLA antibodies by solid phase immunoassay (Flowcytometry) Flowcytometry : 1. In house method in which whole lymphocytes are used as the Ag. 2. Commercially kits which employ beads coated with specific HLAantigens. HLA- A, B, Cw, DR, DQ, and DP coated beads have been used and shown to be much more sensitive than the CDC method. Advances in this methodology result in the introduction of single antigen coated beads. This method helps identifying the specificity of PRA in highly sensitized patients and improves the definition of acceptable mismatches. This method s Limitation are: - Only 8 specificity can be tested in each tubes - Labor intensive, takes six hours to perform the assay - High cost, for additional specificities it is necessary to buy supplemental kit - Can not determined the level of bound antibody

34 Assessment of anti HLA antibodies by solid phase immunoassay) ( Flowcytometry) Only 8 specificities can be tested in each tube Initial kit requires 4 tubes/sample 6 hrs to perform assay (labor intensive!) If additional specificities are required, supplementary kits are available ( cost) Level of antibodies can not assess

35 Assessment of anti HLA antiantibodies by solid phase immunoassay (Luminex 200anal) controls + 96 specificities (class I) or 76 specificities (class II)/ well Arrays Bead technology with liquid technology higher sensitivity than other assays high specificity No well to well variation high percision High through put up 9600 analyte Less analysis,assay time 2 hours Economically,less labor intensive High flexibility

36 Performance / double discriminator / bead map Double discriminator (Doublet temperature) Bead MAP

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38 Consequences of sensitization Patients awaiting transplantation, who have Abs against HLA Ags either currently or in past, will have greater difficulty in finding a compatible organ donor than will un sensitized patients. Compared with unsensitized patient sensitized patient wait longer for transplantation and are at greater risk for rejection episodes when they do receive a graft.

39 Cross reactive Groups of Ags (CREGS) The phenomenon of CREGS results from the sharing of these public epitopes among group of HLA alleles. Patients with high titers of antibodies against HLA Ag are frequently found to have made Abs against only one or two CREG Ag rather than against multiple private HLA Ag.

40 Cross reactive Groups of Ags (CREGS) The phenomenon of CREGS results from the sharing of these public epitopes among group of HLA alleles. Patients with high titers of antibodies against HLA Ag are frequently found to have made Abs against only one or two CREG Ag rather than against multiple private HLA Ag.

41 Antibodies relevant to transplantation rejection Recognition of Antibodies in recipient: Anti ABO blood groups antibodies Anti-HLA-specific Antibodies: Risk of rejection correlates with the presence of HLA-specific Abs both anti-class I and/or anti-class II. Post transplant anti-donor antibodies; Recent studies suggest that development of IgG Anti-HLA Abs post transplant correlates with chronic rejection in renal and heart recipients. Historic versus current Abs containing sera if retransplant with the same mismatched Ag Other antibodies significance in graft rejection: Anti MICA antibodies, anti angiotensin receptor (ATR) Anti public epitope cross reactive antibodies

42 Anti cross reactive Groups of Ags (CREGS) A cross reactive group of HLA Ag is defined by the reaction pattern of an antiserum that reacts with multiple Ags even thought it was, in fact, produced in response to a single Ag. for example the Abs in pregnancy serum was produced from immunization by a single private Ag of the paternal haplotypes of the baby, for example B7. However the serum will also react with Ags B27,55,56,60 and 61. these Ags are considered to be members of the B7 CREG.