Anti-idiotype stimulation of antigen-specific antigen-independent antibody responses in vitro. II. Triggering of B lymphocytes by idiotype plus anti-idiotype in the absence of T lymphocytes.

Antibodies specific for the idiotypes of B10 anti-(T,G)-A--L antibodies (anti-id) induced B lymphocytes to secrete anti-(T,G)-A--L antibodies in vitro in the absence of both antigen and T lymphocytes, provided either that the B lymphocytes were previously primed in vivo with (T,G)-A--L or that id specific for (T,G)-A--L was added to the cultures. These antigen- and T lymphocyte-independent responses were antigen specific and appeared not to require accessory cells. The results suggested that B lymphocyte activation occurred via the formation of id-anti-id complexes, and evidence was obtained that this activation involved two separate interactions between the B lymphocytes and the id-anti-id complexes. These studies document a previously undescribed regulatory function of anti-idiotype antibodies.