Perforins are proteins associated with the activity of

(a) T cells

(b) B cells

(c) NK cells

(d) Plasma cells

Where do T cells undergo central tolerance selection?

What is immunological tolerance?

Explain why a patient with AIDS due to HIV is at an increased risk of infection and of developing certain cancers.

Mark the following statements as true or false. If a statement is false, correct is to make a true statement.

The secondary immune response is mediated by plasma cells.

How does a cytotoxic T cell destroy another cell displaying antigens bound to class I MHC proteins?