Lymphocytes Flashcards
Half of all nucleated cells in the blood are lymphocytes, what are the proportions of these lymphocyte subsets
60% T cells
20% B cells
10% NK cells
Where are the majority of lymphocytes located at any one time
Majority secondary lymphoid tissue
Only 2% in the blood
How can the proportion of CD4 vs CD8 T lymphocytes be analysed
Lymphocyte immunophenotyping (easy)
Monoclonal antibodies to surface marker with fluoro dyes, then use flow cytometer
Dye 1 on anti-CD3
Dye 2 on anti-CD4
Distinguishes CD8, CD4, B & NK cells
Two advantages of lymphocyte recirculation
- More opportunities for different lymphocytes to contact antigen - reduces time for clonal selection
- Activated lymphocytes then become randomly distributed throughout lymphoid tissue
Name 3 molecular components of the innate immune system
- Pro-inflammatory cytokines - TNF, IL1, IL6
- Acute phase proteins - CRP
- Complement system
How do B and T cell antigen receptors differ?
B - surface antibody. After clonal selection + proliferation plasma cells secrete this
T - structurally similar to antibody, but are not secreted
Where do T vs B cells develop
Both begin in BONE MARROW from haemopoietic stem cells
B cells BONE MARROW then blood
T cells THYMUS then blood or 2nd lymphoid organ
Both tested for self-reactivity before leaving
Which surface antigen is present on all T cells?
CD3
Definition of antigen
Substance that generates any kind of adaptive immune response
What does the innate immune cells respond to
DAMPs & PAMPs
Describe NK cell recognition of a foreign cell
Stop and Go signal
Enough MHC1 - inhibitory signal
Too little MHC1 (stress) - Kill and secrete INF-gamma to stimulate resident macrophages
How do lymphocyte antigen receptors acquire diversity
In immature lymphocytes DNA of TcR/Antibody genes are rearranged:
- Combinatorial diversity - VDJ
- Junctional diversity - adding/removing nucleotides
