Chapter 6 Flashcards
what is the activation process of CD4+ cells?
what cells are involved and what costimulator molecules are involved (2nd signal)
extracellular antigen (foreign protein) is phagocytosed, processed, and presented on MHC class II
B7 on APC binds CD28 on CD4 t cells providing 2nd signal
what are the two subsets of CD4 t cells
TH1 and TH2
TH1 subset
cytokines and functions
IL-2
-t cell growth factor and CD8 T cell activation
IFN-gamma- macrophage activator
TH2 subset
cytokines and functions
IL-4 -B cell class switching to IgG and IgE
IL-5
-esosinophil chemotaxis and activation
maturation of B cells to plasma cells
class switching to IgA
IL-10
-inhibits TH1 phenotype
CD8 cytotoxic T cell activation
what provides the second signal?
intracellular antigen (derived from proteins in the cytoplasm) is presented on MHC Class 1
IL-2 from CD4+ TH1 cells provide 2nd activation signal
Cytotoxic t cells are activated for killing
what cells express class 1 MHC
all nucleated cells and platelets
how do CD8 cells kill
secretion of perforin and granzyme –
-perforin creates pore that allows granzyme to enter the target cell activating apoptosis
expression of FasL which binds Fas on target cells , activating apoptosis
what are the steps involved in granuloma formation
macrophages process and present antigen via MHC class II to CD4 helper T cells
interaction leads macrophages to secrete IL-12 inducing CD4 helper T cells to differentiate into TH1 subtype
TH1 cells secrete IFn-gamma which converts macrophages to epitheloiid histiocytes and giant cells
B cell activation
what other cells are involved
what costimulator molecules
antigen binding by surface IgM or IgD results in maturation to IgM or IgD secreting plasma cells
B-cell antigen presentation to CD4 helper T cell via MHC Class II
CD40 receptor on B cell binds CD40 L on helper T cells providing 2nd activation signal
Helper T cell then secretes IL-4 and IL-5 (mediate B -cell isotype switching, hypermutation, maturation to plasma cells)
autoimmune diseases are caused by loss of self tolerance.
self reactive lymphocytes are normally regulated by what mechanism
apoptosis- negative selection in the thymus (T cells) or bone marrow (B cells )
anergy- due to recgonition of antigen in peripheral lymphoid tissues with no 2nd signal
what is CREST syndrome
Calcinosis raynauds esophageal dysmotility sclerodactyly telaniectasia
