Immune response to haptenated syngeneic and allogeneic lymphocytes. I. Restrictions for B cell activation by haptenated lymphocytes and specificity of the antibodies generated.

The B cell immune response to altered self was studied using fluoresceinated syngeneic and allogeneic lymphocytes as antigens. Antibody synthesis could be induced in mice injected with syngeneic or allogeneic haptenated lymphocytes as well as heterologous labelled red cells using one particular hapten density. The response to haptenated syngeneic lymphocytes was thymus-independent since nude mice gave a strong response even when the immunogen was FITC-labelled nude cells. The antibodies induced reacted with a complex between a self structure and the hapten, since the best response was detected using FITC-labelled mouse erythrocytes as targets in the plaque assay. These results indicate that a clear distinction must be made between recognition and activation of the responding B cells. The nature of the structures on the modified lymphocyte required to perform these two functions is discussed. It is pointed out that in a dual recognition model of altered self, the duality involved may concern recognition and activation events, rather than two recognition receptors.