Antibody Plaque-Forming Cells in Unsensitized Mice

Abstract

Summary Using the standard antibody plaque technique, numbers of background anti-sheep erythrocyte plaque-forming cells (PFC’s) in spleens of unsensitized mice were determined after neonatal thymectomy, after whole body x-irradiation and after injection of phytohemagglutinin-M or typhoid parathyphoid vaccine. The results show that numbers of background PFC’s 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 to 20 fold) by phytohemagglutinin, typhoid vaccine and other unrelated antigens. Simultaneous determinations of background anti-sheep erythrocyte and anti-horse erythrocyte PFC’s indicate that these two populations are independent of one another. From these and other studies it is concluded that background PFC’s 1) produce specific hemolysin, 2) are thymus independent, 3) are relatively long lived (average life time τ; 7 days) and 4) are not related to the antigen-sensitive precursor cells of the primary response PFC’s.