Which Cells Secrete a Lymphokine That Stimulates Both T and B

Question

Which cells secrete a lymphokine that stimulates both T and B cells?
A) Platelets
B) Killer T cells
C) Erythrocytes
D) Helper T cells

Accepted Answer

Helper T cells secrete various lymphokines such as interleukin-2 (IL-2), which can stimulate both T and B cells. Platelets and erythrocytes are not known to secrete lymphokines, and killer T cells primarily involve the killing of infected cells.