Abstract
The presence of two surface markers, IgM for B-cells and θ-antigen for T-cells, was examined radioautographically on small lymphocytes appearing in subcutaneously grown TA-3 (Stockholm) line tumor in strain A mice, as well as in the spleen and blood at different days of tumor growth. IgM-positive cells were identified by surface labeling which resulted from a direct binding of 125l-labeled antimouse IgM raised in goats. Labeling of additional small lymphocytes resulting from an exposure of cells to anti-θ-antibody prior to incubation with 125l-labeled anti-lgM provided the incidence of θ-positive cells. Cells remaining unlabeled with the latter procedure were considered as double negative. When compared to the small lymphocytes in normal tissue (peritoneal) space, the proportion of IgM-positive cells declined, that of θ-positive cells remained unchanged, and that of double-negative cells increased markedly within the developing tumors. Absolute numbers of all three subsets within the tumor rose with increase in tumor age. Within the spleen, the proportion of IgM-positive cells remained unchanged, that of θ-positive cells declined, and that of double-negative cells increased substantially. Despite splenomegaly, the absolute number of θ-positive small lymphocytes in the spleen remained unchanged with time, while the remaining two subsets increased. In the circulation, the proportion of IgM-positive small lymphocytes showed an initial decline followed by a recovery, that of θ-positive cells declined, and that of double-negative cells increased significantly. The significance of an increase in the size of double-negative small lymphocyte populations within the tumor as well as other sites in the tumor-bearing host remains to be determined.