ANTIBODY PLAQUE-FORMING CELLS IN UNSENSITIZED MICE: SPECIFICITY AND RESPONSE TO NEONATAL THYMECTOMY, X IRRADIATION AND PHA,

Using the standard antibody plaque technique, numbers of background anti-sheep erythrocyte plaque-forming cells PFCs in spleens of unsensitized mice have been determined after neonatal thymectomy, after whole body X irradiation and after injection of phytohemagglutinin-M or typhoid paratyphoid vaccine. The results show that numbers of background PFCs are not affected by neonatal thymectomy or by whole body X irradiation at dose levels known to inhibit cellular proliferation, but that they are significantly increased 10-20 fold by phytohemagglutinin, typhoid vaccine and other unrelated antigens. Simultaneous determinations of background anti-sheep erythrocyte and anti-horse erythrocyte PFCs indicate that these two populations are independent of one another. From these and other studies it is concluded that background PFCs 1 produce specific hemolysin, 2 are thymus independent, 3 are relatively long lived average life time 7 days, 4 are not related to the antigen sensitive precursors of the primary response PFCs. Author