The following interleukin is characteristically produced in a TH1 response?: (A) IL-2, (B) IL-4, (C) IL-5, (D) IL-10
Answer is A. After coming in contact with antigen presenting cells, CD4+ helper T cells secrete IL-2 and expresses high-affinity receptors for IL-2. IL-2 is a growth factor that acts on these T lymphocytes and stimulates their proliferation, leading to an increase in the number of antigen-specific lymphocytes.