experiments were designed to test two hypotheses of b-cell activation by antigen : the cross-linking concept , postulating that a suitable degree of antigen-induced cross-linking of the ig receptors is sufficient for immunocyte triggering , and the two-signal hypothesis , suggesting that a first signal delivered by antigen interacting with the ig receptors followed by a second signal given by , for example , a polyclonal b-cell activator is necessary for activation .
C1155003
b-cell activation
C0003320
antigen