Introduction to the Immune System Flashcards
What are the parts of a lymph node? What kind of cells are found in each part?
- cortex/follicle = B
- germinal center = antibody production
- paracortex = T
- medulla = macrophage
Which cells are part of the first line of defense?
macrophages and neutrophils
granulocyte CD marker
CD15+
monocyte CD marker
CD14+
DC CD marker
CD11c
T cell CD marker
CD3+
helper T cell CD marker
CD4+ and CD3+
killer T cell CD marker
CD8+ and CD3+
B lymphocytes
CD19+
NK cells
CD56+
What are sites of antigen entry, initial capture, and collection?
- entry = skin, GI, lungs
- initial = connective tissue
- collection = lymph nodes or spleen
What are self markers?
MHC - major histocompatibility complex
HLA - human leukocyte antigens
mark a cell as being part of the human body
Which cells express class I MHC?
all nucleated cells;
Which cells express Class II MHC?
B cells, monocytes, macrophages, DC
What is an antigen?
- substance that generates an antibody
- can be whole cell or particles of a foreign invader
What is an epitope?
multiple antigenic components that are recognized and trigger an immune response
Describe innate immunity.
- short
- nonspecific
- initial
- mediated by macrophages, granulocytes, and NK cells
Describe adaptive immunity
- longer duration
- specific
- mediated by B and T cells
- results in activation, differentiation, and clonal expansion
Describe B-mediated humoral immunity
- APC recognition (in lymph node)
- activation
- clonal expansion
- differentiate into antibody-producing plasma cell
- produce antibody
- memory B cell
Describe T cells
either produce cytokines (helper T cells) that recruit other immune cells or kill cells on contact with chemicals, like perforin or granzymes (killer T cell)
What are the phases of an adaptive response?
- recognition due to APC
- activation of T and B cells
- clonal expansion
- differentiated into effector cells
- kill antigen
- memory cells remain
Describe the mechanism of cell-mediated immunity
- APC breaks down antigen and displays the peptide on a Class II MHC molecule
- helper T cell receptor recognizes antigen => activation
- helper T cell produces cytokines to recruit plasma cells and killer T cells
- helper T cell cytokines allow for clonal expansion and differentiation
- differentiated killer T cells roam the body to look for that antigen, recognizing it on Class I MHC molecules
Describe primary vs secondary response.
primary response = initial encounter with antigen
secondary response = faster, longer duration, and greater response
Describe active vs. passive immunity.
active = through acquired infection or vaccination; body is prepared for the antigen passive = immunity is given through exposure to antibody-rich serum (babies)
Identify the role of MHC molecules in T cell immunity.
MHC molecules are present on APCs and on nucleated cells. Antigens on MHC molecules bind to T cell receptors.
Contrast humoral and cell-mediated immunity.
humoral = antibody is freely floating in the blood and marks invaders and infected cells for immune cells
cell-mediated immunity = cytokines used to kill cell
