Adaptive immunity I: B cells

Question 1

B lymphocytes

Answer 1

An antigen specific lymphocyte responsible for the adaptive immune response. The function of B cells is to become plasma cells and produce antibodies

Question 2

BCR (B Cell Receptor)

Answer 2

The cell surface receptor on B cells for specific antigen. It is composed of a transmembrane immunoglobulin molecule i.e. tethered antibody.

Question 3

Naïve B cell

Answer 3

A B cell that hasn’t encountered its specific antigen

Question 4

Somatic hypermutation

Answer 4

Mutations in variable region of rearranged DNA of heavy and light chain genes due to conversion of cytosine to uracil.

Question 5

Class switching

Answer 5

The gene recombination process found in activated B cells that replaces the heavy chain constant region from μ which gives IgM with another of different isotype i.e. changing the antibody from IgM to the production of IgG, IgA or IgE. This affects their function but not the antigen specificity

Question 6

Plasma cell

Answer 6

Terminally differentiated activated B cells. They are the main antibody secreting cells of the body.

Question 7

Memory B cell

Answer 7

B lymphocytes that mediate immunological memory. More sensitive and more rapidly activated than naïve T cells, so respond rapidly on reexposure to the antigen that originally induced them

Question 8

V(D)J recombination

Answer 8

The process in developing lymphocytes that recombines different gene segments (Variable gene segment (V), Diverse gene segment (D) and joining gene segment (J) ) into sequences that code for the variable regions of TCR and BCR proteins.