Which of the following statements concerning T helper cells is true?
A. They possess membrane-bound antibodies B. They can recognize and interact with antigens in the blood. C. They produce numerous cytokines D. They function only in cell-mediated immunity. E. Their activation depends on interferon y.
T helper cells produce a number of cytokines that affect other cells involved in both the
cell-mediated and the humoral immune responses.
T helper cells possess antigen-specific T-cell receptors (not antibodies) on their membranes. These cells recognize and interact with antigenic determinants that are associated with class II human leukocyte antigen (HLA) molecules on the
surface of antigen-presenting cells. IL-1 is necessary for activation of T helper cells.