LBL 3 terms/discussion questions posted BNG Seminar Monday! Lippman 017, Common Hour (w/ lunch) Julie Czupryna, Ph.D.

Transcription

1 The Immune System

2 Some updates LBL 3 terms/discussion questions posted BNG Seminar Monday! Lippman 017, Common Hour (w/ lunch) Julie Czupryna, Ph.D. Technical Director, Optical Imaging Core, Upenn Beyond the Knife: Noninvasive Imaging of Disease in Small Animals Outline for today HW 3 discussion Animation recap of inflammation Acquired immunity 1

3 Homework 3 discussion For those of you I wrote a note to offering a redo (and use of grace period), please see me today Office hours this afternoon is fine (bring HW with you) General points Very few commented on the information that the color in the stains provides that black/white sketches cannot! Cite source(s) for images used In some cases, incorrect to say the size of the cells in sketches were smaller Can only do this if there is a common element (scale bar or other cell type) Let s see an example!

4 Example Homework 3

5 INFLAMMATION SUMMARY

6 The Immune System The immune system is complex and immunology is a broad field of study We will focus on the fundamentals of the immune system and its link to the inflammation process

7 Immunity Introduction Human body has 2 general kinds of immunity Innate immunity Skin (protective barrier) Enzymes in the stomach Enzymes in the blood Phagocytosis! Acquired (or adaptive ) immunity Methods of resistance in response to specific, individual foreign organisms/stimuli Survivor immunity?

8 Immunity Introduction Acquired/innate immunity combine to give the following characteristics: Specificity Discrimination between a large number of stimuli Memory Subsequent exposure to stimuli induces a faster and stronger response Self-knowledge Any foreign object is distinguished from self objects Let s take a closer look at acquired immunity

9 Immunity Introduction Acquired immunity has 2 subtypes Humoral immunity from chemical activation of antibodies Cell-mediated immunity arises from cytotoxic action of cells humoral cell-mediated Immunity results from the action of two main classes of lymphocytes

10 Lymphocytes 3 blood cell types Platelets (thrombocytes) RBCs (erythrocytes) Leukocytes (all others!) HSC Lymphatic Leukocytes Lymphocytes Nonlymphatic Leukocytes * *

11 Lymphocytes develop in the bone marrow develop in the thymus ~5-10% ~65-75% ~10-15% Will talk about these on next slide

12 Natural killer (NK) cells NK cells named as such because it was thought activation was not required 2011 NK cells are considered to represent an arm of the innate immune system. However NK cells may manifest adaptive features Recent data suggests NK cell production occurs in lymph nodes and tonsils (2 lymphoid tissues) as opposed to BM alone We will see roles of NK cells in a few different places in immunity

13 Immunogens versus antigens Antigen substance that evokes the production of (and is subsequently recognized by) one or more immunoglobulins (antibodies) antibody generator Immunogen substance that can induce an adaptive immune response if injected on its own All immunogens are antigens, but not vice-versa! hapten (antigen) carrier molecule antigen or immunogen? bacteria & viruses immunogens (also antigens)

14 Epitopes Epitopes - also called antigenic determinants are the specific chemical sites on antigens that bind either antibodies or T-cell receptors (fragment, antigen binding region)

15 Adjuvants The immune system response to a relatively weak antigen can be enhanced by mixing it with an adjuvant The adjuvant is rarely antigenic by itself Typical application enhance effectiveness of vaccines Types of vaccines use components of the pathogen (e.g., virus or bacteria) itself Types of adjuvants salts virosomes organic compounds

16 Cell-mediated immunity Cell-mediated immunity primarily mediated by T- cells (T-lymphocytes) Antigens are detected by their interaction with receptors on the T-cell membranes T-cells express a number of characteristic cellsurface proteins known as CD cluster of differentiation

17 Cell-mediated immunity Cytotoxic T-cells express an additional CD (CD8+) Role is to directly attack and kill cells that express stimulatory agents Antigen_presentation.svg Helper T-cells do not express CD8, but rather express CD4+ Role is to secrete chemicals (lymphokines) that help regulate the body s immune response