Surface antigen determinants in subpopulations of peripheral blood NK- and T-cells separated by Percoll density fractionation.

Subpopulations of NK-cells recovered in various Percoll fractions had similar Leu 7 (HNK-1) antigenicity. Leu 11 paralleled Leu 7 in its expression in the high density Percoll fractions, while cells in the lowest density showed a somewhat higher reactivity with Leu 11 than with Leu 7 antibody. A similar small proportion (20-30%) of NK-cells recovered in all Percoll fractions was susceptible to lysis by treatment with T8 and complement. Exposure to T11 and complement, which eliminate approximately 50% of the NK activity in unfractionated PBL, reduced the cytotoxicity of NK-cells recovered in the high density fraction to a significantly greater extent (60%) than that of those recovered in the low density (30%). Flow microfluorometry analysis using monoclonal anti-T reagents showed that while Leu 4 (pan T-marker) was expressed on all high density T-cells, a subpopulation of low density T-cells did not express this antigen. The proportion of Leu 3a positive (helper T) cells was found to be significantly higher among the high density T-cells than among the low density T-cells. There was a relative enrichment of Leu 2a positive (cytotoxic/suppressor T) cells recovered in the lower density Percoll fractions. Subsets of NK- and T-cells, differing in their density, were thus shown to also differ in their cell surface antigenic markers. Percoll density fractionation may prove to be a valuable tool for separation and analysis of NK- and T-cell subsets.