Factors influencing activation of B-cells in immunity.

The hypotheses so far advanced for B-cell activation by antigen are based on the assumption that the interaction between antigen and the Ig receptors delivers at least the initial triggering signal. There are few, if any, experimental findings to support this assumption. On the contrary, a variety of findings indicate that the Ig receptors do not deliver any signal to the cells, whereas activation can be regularly achieved without participation ofIg receptors. The available evidence forces us to suggest that antigen-induced B-cell triggering is always caused by one nonspecific signal, which is delivered to the cells by surface structures, which are not the Ig receptors. For distinctive features of this hypothesis see One Nonspecific Triggering Signal. Various competing hypotheses for B-cell activation have been analyzed, but none of them appears to satisfy the experimental findings.