Lecture 21 - Cell Mediate Immunity and Lymphocyte Ontogeny

Question 1

Problems with Antisera?

Answer 1

range of epitopes recognised with different affinities (polyclonal) - cannot use therapeutically

Question 2

Monoclonal production?

Answer 2

fusing antibody producing cells with B cell tumour cells (myeloma) - single epitope with single affinity

Question 3

Killing mechanisms?

Answer 3

perforin + enzymes for polymerisation, granzymes, (hydrolytic enzymes), cytokines (leading to apoptosis)

Question 4

B Cell Ontogeny?

Answer 4

uncommitted stem cell -> pre-B cell (cytoplasmic heavy chains) -> immature B cell (surface IgM), -> mature B cell (surface antibodies IgG)

Question 5

Immunoglobin genes?

Answer 5

heavy and light chains from different germ lines, high variability in the variable regions due to combination options and imperfect splicing, non-reversible transcription means specificity of B cell Ig

Question 6

Central tolerance?

Answer 6

clonal deletion of immature B cells showing self-antigen exposure preventing auto-immunity

Question 7

Class switching?

Answer 7

T cells control S-S rearrangement relocating exons and changing constant regions of heavy chain (therefore class) w same antigen binding site - explains IgM to IgG change during primary-secondary response

Question 8

Exons?

Answer 8

V D and J - recombine to form variable regions, B cell becomes constant in heavy and light chain formation

Question 9

T Cell ontology?

Answer 9

uncommited thymocyte undergoes TCR gene rearrangement commiting to certain alpha and beta chain, expresses both CD4 and 8, undergoes positive selection (no HLA recognition = deth), undergoes negative selection (anti-self HLA or peptide = deth), gain CD3 and export to second. lymph organs