4 - Adaptive Immunity

BCR cells for B cell immunity

B cells receptors (BCR) recognise surface structure on pathogens. (MEMORY)

BCR binds to pathogen —secretes receptor→ antibody or immunoglobulin stuck on pathogen

• random BCR generated in each B cell to prevent future pathogens.

BCR (antibody) produced randomly from many gene regions and then replicated by transcription and translation

Antibody structure

Antibody/Antigen Binding

Many epitopes make up an antigen, many antigens make up a bacteria or wtv.

Different constant regions

IgM - first antibody produced in new immune response - can form multimers

IgG - Can cross the placenta - can form multimers

IgA - predominant antibody at mucosal sites

IgE - attaches mast cells to parasitic worms

IgD - function unknown

Antibody levels during an immune response

Lag phase - due to acute inflammation from innate response

Primary response - IgM more prominent because first antibody produced in new response

Functions of Antibodies

Use of antibodies in research and clinical applications

Immunoflourescence -

• put a cell into a foreign body to create antibodies of that cell.

Role of T cells in adaptive immunity

Each T cell randomly generates a T cell receptor (TCR) that is membrane bound to that specific T cell.

T cells cannot see raw pathogens. Rely on specific MHC molecules to present specific peptides in order to activate.

Where do peptides come from to bind MHC

T cells functions

1. Helps B cells to produce antibody

2. Kill virally infected cells

3. Secrete cytokines to amplify inflammation

4. Suppress the immune response (regulatory T cell or Treg)

5. Assist macrophage phagocytosis

T and B cell differentiation