Restoration of in vitro responsiveness of xid B cells to TNP-Ficoll by 8-mercaptoguanosine.

8-Mercaptoguanosine (8sGuo) has been reported to enhance responses of normal mice to the type 2 antigen trinitrophenol (TNP)-Ficoll. In this report, we demonstrate that this immune adjuvant restores the immune responsiveness of B cells from mice with the x-linked immune defect (xid), which are nonresponsive to the type 2 antigen TNP-Ficoll. The data demonstrate that TNP-Ficoll, which by itself cannot stimulate anti-TNP responses in CBA/N mice, is able to initiate the initial steps of cell activation in xid B cells and render them sensitive to the subsequent differentiative effects of 8sGuo. We propose that the unresponsiveness of xid B cells to type 2 antigens reflects not the inability of these antigens to stimulate xid B cells from G0 to G1, but rather the inability of these antigen-activated cells to respond to a second signal to which these immune defective B cells are poorly responsive and can be substituted for by 8sGuo.