The following are true for T lymphocytes except -

The adaptive immune system consists of 2 types of lymphocytes: T-cells (70-80% of the adaptive immune force) and B cells (10-20% of the adaptive immune force).Antigens (triangular shapes above) are ingested (1), paially digested (2) and then presented to helper T cells by special cells called macrophages (3). This process activates the helper T cell to release hormones (lymphokines) that help B cells develop (4). These hormones, along with recognition of fuher antigens (5), change the B cell into an antibody-producing plasma cell (6). The antibodies (Y shapes above) produced can be one of several types (IgG, IgM, IgA, IgE and IgD) (7). The antibody "fits" the antigen much like a lock fits a key. The antigen is thus rendered harmless. The helper T cells also aid in development of cytotoxic T cells (8), which can kill antigens directly; memory T cells are produced (9) so that re-exposure to the same antigen will provide a more rapid and effective response (10). Reff: www.mayoclinic.com