Activation requirements of cloned inducer T cells. II. The failure of some clones to respond to antigen presented by activated B cells.

Inducer/helper T cells recognize nominal antigen in association with Ia on the surface of the antigen-presenting cell (APC). Recent studies have shown that B cells can effectively function as APC. In the present study we have assessed the ability of cloned inducer T cells to discriminate between activated B cells or splenic macrophages as APC. We found that most of the clones tested demonstrated an equivalent response to antigen presented by activated B cells or splenic adherent cells. Some clones were very efficiently stimulated by antigen presented by activated B cells, whereas other clones failed to respond or responded very poorly when activated B cells were used to present antigen. We attempted to determine the mechanism responsible for the inability of certain clones to proliferate in response to antigen presented by activated B cells.