Stimulation and membrane charge changes of spleen cells by factors of low molecular weight associated with murine solid tumors.

Dialysates from a slow-growing VMM2 and a fast-growing RV2 solid murine tumor were fractionated on a Sephadex G-50 column. Similar elution profiles with two peaks were obtained in both cases. Fractions I and II, corresponding to these two peaks were tested for their mitotic properties on lymphocytes in culture and their effect on the negative surface charge of spleen cells by the electrophoretic mobility measurement (EPM) technique. Fraction I from both tumors presents a similar mitogenic action on C3H/He or nu/nu lymphocytes in culture. Incubation for 1 h at 37 degrees C of normal mice spleen cells with fraction I from RV2 or VMM2 tumors did not affect the mean electrophoretic mobility of spleen cells. Fraction II from VMM2 tumor induced a significant decrease in the mean electrophoretic mobility of spleen cells (-13.4%), while fraction II from RV2 tumor increases the EPM (+ 9%) significantly. Incubation with T cell-enriched or B cell-enriched populations or spleen cells from nu/nu mice shows that fraction II from VMM2 interacts with T cells but not with B cells. Fraction II from RV2 increases the T and B cell electrophoretic mobility.