X-ray resistant cell required for the induction of in vitro antibody formation.

Mouse spleen cells were separated into two populations on the basis of adherence to plastic. The recombination of these two populations was required for the in vitro antibody response to sheep erythrocytes. By separating the two populations from x-irradiated mice and combining each with the other population prepared from normal mice, it was demonstrated that the immunologic function of the nonadherent population only was highly sensitive to x-ray injury. In contrast, x-irradiation in doses as high as 1000 roentgens had no measurable effect on the immune function of adherent cells, that is, the population which first interacts with antigen and is composed principally of large phagocytic cells.