Question

Which of the following is true of NK cells?

Select one:

a. NK cells are a type of neutrophil

b. NK cells are a main part of cell-mediated immunity

c. NK cells are rarely present in the blood

d. NK cells attack cells displaying any form of MHC antigen

e. NK cells are given antigen signals by body cells to determine which are infected/cancerous

Answer 1

I would select the last option (e) is true.

NK cells are circulating lymphocytes (not neutrophills,not rare),which are different from T and B cells(lack features of either type) is a type of null cell.

Nk cells are main part of innate immunity not cell mediated immunity.Thus normally active in SCID.

These cells possess spontaneous cytotoxicity towards malignant and virus infected cells,which is neither antibody dependent nor MHC restricted.Thus they do not display any type of MHC antigen.

They have CD16,CD56 on their surface.They bind to glycoprotein receptors on surface of autologous as well as allogenic target cells and release several cytolytic factors(perforins)_destroy cell by apoptosis.NK cell function augmented by interferons.They are considered important in immune surveillance and natural defence against virus infected cell and malignant mutant cells. Thus last option is correct.