Question

This lymphocyte is responsible for killing infected cells following MHC I binding Group of answer choices

Cytotoxic T cells

Memory B cells

Helper T cells

Plasma B cells

Answer 1

Answer: ‘cytotoxic T cells’

Explanation: T cells are the type of lymphocytes which are of three different types; T helper, T suppressor, and T cytotoxic.

T cytotoxic cells are also known as T killer cells, they are also known as CD8 cells as they display CD8 markers on their surface. These cells are responsible for cell mediated immunity where when the T cytotoxic cells are activated; they create a hole in the target cell with the help of perforins and bring about lysis of the target cell by release of lysing enzymes like proteases.

For the T cytotoxic cell to recognise the antigen, the antigen has to be presented with MHC class I molecules. The antigens are engulfed by the antigen presenting cells, fragmented and then presented along with MHC I on their surface, T cytotoxic cells recognise the foreign antigen and there is clonal expansion of Tc cells because of interleukin-2 molecules and the number of Tc cells increases to target the specific antigen presenting cells.

Note: memory B cells are the antibody producing cells which are generated for the specific antigen. The further attack of the same type of antigen triggers the secondary immune response with the help of memory B cells.

T helper cells are activated by antigen presented by the antigen presenting cells along with MHC class II molecules

Plasma B cells are the transformed B cells. B cells after encountering an antigen change into plasma cells which produces millions of antibodies against the specific antigen.