The effects of tumor bearing upon changes in cell distribution and membrane antigen characteristics in murine spleen and thymus cell subpopulations.

A model system is described for examining the impact of bearing methylcholanthrene-induced tumors upon the van ous lymphoid cell subpopulations of mouse spleen and thy mus. The data define qualitative aspects of the 10-fold increase in numbers of spleen cells, and the equivalent re duction in thymus cells, during the 40to SO-day course of tumor bearing in CS7BL/6 or CBA mouse strains. The pro portion of spleen cells susceptible to anti-O or anti-H-2 plus complement is reduced, but the absolute numbers increased progressively. The proportion of anti-H-2-susceptiblc thy mus cells increased markedly. These changes are inter preted as reflecting a net increase in T-cells in the spleen during tumor bearing. The proportional reduction in T-cells in the spleen, therefore, appears to represent a dilution ef fect, whereas, in fact, a net increase in total spleen T-cells occurs.