IMMUNE RESPONSE Dr Mohit Bhatia Assistant Professor Department
IMMUNE RESPONSE Dr. Mohit Bhatia Assistant Professor Department of Microbiology AIIMS, Rishikesh
LAYOUT • INTRODUCTION • ANTIGEN PRESENTATION • CELL MEDIATED IMMUNE RESPONSE • HUMORAL IMMUNE RESPONSE • AN OVERVIEW OF CYTOKINES
INTRODUCTION • Immune response refers to highly coordinated reaction of the cells of immune system and their products • Cell mediated immune response: T cells • Humoral immune response: Antibodies
ANTIGEN PRESENTATION
ANTIGEN PRESENTING CELLS
DIFFERENCES BETWEEN DIFFERENT APCs
PATHWAYS OF ANTIGEN PRESENTATION
ENDOGENOUS (MHC I) EXOGENOUS (MHC II)
CELL MEDIATED IMMUNE RESPONSE
Development of αβ T cells
Positive & Negative selection of thymocytes results in mature T cells that are both self-MHC restricted & selftolerant
INSTRUCTIVE & STOCHASTIC MODELS
T CELL RECEPTOR-CORECEPTOR COMPLEX & OTHER SURFACE MOLECULES
INTERACTIONS BETWEEN T CELLS & APCs
OVERVIEW OF TCR MEDIATED SIGNALING
TH-cell activation requires a co-stimulatory signal provided by APCs
CONCEPT OF CLONAL ANERGY
Super-antigen mediated cross-linkage of T-cell receptor and class II MHC molecules TSST-1 EXFT SPE- A, B, C, D
üActivation of TH cells by signal 1 & co-stimulatory signal 2 up-regulates expression of IL-2
FEATURES OF NAÏVE & EFFECTOR T CELLS
EFFECTOR MOLECULES PRODUCED BY EFFECTOR T CELLS
GENERATION OF EFFECTOR CTLs
STAGES IN CTL MEDIATED KILLING OF TARGET CELLS
CTL MEDIATED PORE FORMATION IN THE TARGET CELL MEMBRANE
PATHWAYS OF TARGET CELL APOPTOSIS STIMULATED BY CTLs
ASSESMENT OF CMI • Mixed lymphocyte reaction • Cell mediated lympholysis • Graft versus host reaction
NK CELL MEDIATED KILLING: OPPOSING SIGNALS MODEL
Antibody-Dependent Cell-Mediated Cytotoxicity(ADCC)
ANTIBODY DEPENDENT CELL MEDIATED CYTOTOXICITY (ADCC)
HUMORAL IMMUNE RESPONSE
OVERVIEW OF B CELL DEVELOPMENT
Pro-B CELL & BONE MARROW STROMAL CELL INTERACTION
B-CELL RECEPTOR-CORECEPTOR COMPLEX
THYMUS INDEPENDENT & DEPENDENT ANTIGENS
PROPERTIES OF TI & TD ANTIGENS
B-CELL MEDIATED IMMUNE RESPONSE
B-CELL MEDIATED RESPONSE
üSchematic diagram of a peripheral lymph node showing anatomic sites at which various steps in B-cell activation, proliferation and differentiation occur. üThe cortex is rich in B cells & the paracortex in T cells. üBoth B and T cells are present in large numbers in the medulla. üA secondary follicle contains the follicular mantle and a germinal center.
OVERVIEW OF CELLULAR EVENTS WITHIN GERMINAL CENTERS
The interactions of numerous cytokines with B cells generate signals required for proliferation and class switching during the differentiation of B cells into plasma cells
NAÏVE & MEMORY B CELLS
PRIMARY & SECONDARY IMMUNE RESPONSE
COMPARISON OF PRIMARY & SECONDARY IMMUNE RESPONSES
EFFECTOR FUNCTIONS OF HUMORAL IMMUNITY
Neutralization Toxin receptors Bacterial toxins Host cell Neutralization by antibody Fc Forming phagosome receptor Phagocytosis of antibody-antigen complex by macrophage
Opsonization Extracellular bacteria Opsonization Macrophage Ingestion by macrophage Digestion in lysosom
Complement Activation Bacteria in plasma Lysis and ingestion C 1 C 2 C 4 C 1 C 2 C 4 Complement activation Digestion in lysosom
TRANSCYTOSIS
AN OVERVIEW OF CYTOKINES
INDUCTION & FUNCTION OF CYTOKINES
ATTRIBUTES OF CYTOKINES
Interaction of antigen with macrophages and the subsequent activation of resting TH cells leads to release of numerous cytokines (blue arrows), generating a complex network of interacting cells in the immune response.
SUMMARY OF CYTOKINES
- Slides: 57