In situ lymphoid cells of mouse mammary tumors. II. The characterization of lymphoid cells separated from mouse mammary tumors.

Lymphoid cells were isolated from mouse mammary tumors by isokinetic gradient centrifugation. theta-bearing and ALS-sensitive cells were always the largest subpopulations found in these tumors. In fractions 4 to 6 from the isokinetic gradient, theta-positive cells ranged from 8 to 46% in autochthonous tumors and 14 to 47% in passaged tumors, and ALS-positive cells ranged from 34 to 46% in autochthonous tumors and 14 to 100% in passaged tumors. SIg-positive cells were only found in occasional tumors and, where present, averaged 2% of the separated population. Fc receptor-bearing cells averaged 15% and phagocytic cells averaged 8% of the cells found in fractions 4 to 6 of the gradient. Occasional ALS-positive and one-third of the Fc receptor-bearing and phagocytic cells also separated in fractions 7 to 10 of the isokinetic gradient. Although the individual tumors were very variable in the proportions of the various lymphoid subpopulations that they contained, this variability was a stable characteristic for at least one passage generation.