Flashcards in Exam Study Deck (29):
Name 4 cells which present MHC class I molecules.
T & B cells
(No unnucleated cells)
Name 4 cells which present MHC class II molecules.
B cells (when upregulated to do so)
T cells (As a rule, they don't always have MHC II but they can)
B Lymphocytes: ORIGIN
(In foetus = liver)
B Lymphocytes: DISTINCTIVE MARKERS
CD19 & CD21
B Lymphocytes: FUNCTION
- Secrete antibody
- Secrete cytokines
- Antigen presenting cell
- Bind antigens
B Lymphocytes: ANTIGEN RECEPTOR
B Cell Receptor (BCR)
- Membrane bound forms of antibodies (IgM & IgD)
- Structurally different
- BCR looks like an antibody
T Lymphocytes: ORIGIN
Bone marrow, mature in thymus
T Lymphocytes: MAJOR FUNCTIONS
- Recognise antigen in context of MHC Class I & II
- Secretion of cytokines
T Lymphocytes: TWO DISTINCT POPULATIONS
- T helper cells = CD4+ (MHC II Restricted) Function is to secrete cytokines.
- T cytotoxic cells = CD8+ (MHC I Restricted) Function is cytotoxic death of infected cell.
T Lymphocytes: ANTIGEN RECEPTOR
T Cell Receptor (TCR)
- Associated with CD3 complex
Compare MHC Class I and MHC Class II
MHC Class I:
- On most nucleated cells
- Endogenous Antigens
- Present to T Cytotoxic cells
MHC Class II:
- On antigen presenting cells
- Exogenous (foreign) Antigens
- Present to T Helper cells.
Neutrophils: % IN BLOOD
40%-75% of WBCs
Neutrophils: MAIN FUNCTION
Neutrophils: 2 TYPES OF GRANULES
Secondary: Lactoferrin, Collagenase
Eosinophils: % IN BLOOD
1%-6% of WBCs
Parasite infection (Eg. Malaria)
Eosinophils: MEDIATES CYTOTOXICITY VIA RECEPTORS
C3b (complement cascade: opsonisation-phagocytosis)
Some proteins are produced by eosinophils too.
Basophils/Mast Cells: ORIGIN
Basophils are similar to mast cells.
- Mast cells, final maturation is in tissue and found in tissue.
- Basophils final maturation is in bone marrow and they are found in the blood.
Basophils/Mast Cells: RECEPTOR
IgE receptor for its role in immediate hypersensitivity reactions.
Basophils/Mast Cells: FUNCTION
Mediators from granules provoke inflammation
- Histamine, serotonin and heparin production/release
- Slow reactive substance of anaphylaxis
- Eosinophil chemotactic factor of anaphylaxis
Filters blood, traps blood-borne antigens. Activation of T and B cells
LYMPH NODE FUNCTION
Two examples of proinflammatory cytokines
IL-1 and IL-18. Important markers. Levels go up in certain conditions that go on for a long time.
Immunoglobulin G (IgG)
- About 80% of total serum Igs
- Can cross placenta
- Only has one Y shape (monomer)
- Complement fixation
- Can act as an opsonin
Subclasses: IgG1, IgG2, IgG3, IgG4
Immunoglobulin M (IgM)
- 5-10% of total serum Igs
- It's a pentamer of 5 monomers bound together by J chain.
- Great at agglutination.
Immunoglobulin A (IgA)
- 10-15% of total serum Igs
- Monomer or two monomer units = dimer
- Secreted immunoglobulin so is associated with mucosal surfaces.
Immunoglobulin E (IgE)
- Very low in concentration
- Role in hypersensitivity (allergies), and parasitic infections
- Induces mast cell degranulation
Immunoglobulin D (IgD)
- 0.2% of total serum Igs
- Don't know a lot about
- Important membrane bound antibody that functions as a B cell receptor.
- Role in certain function of B cells