Comparison of highly NK active human lymphocyte subsets separated by various procedures involving E, EA rosetting,...

Lymphocyte subsets from human blood obtained by different procedures were analyzed for cytotoxic potential and phenotypic characteristics. Nylon wool column passed lymphocytes were fractionated on the basis of: (1) E and Fc gamma receptor expression, (2) cell density and Fc gamma receptor expression, (3) Fc gamma receptor expression. The cytotoxic subsets obtained by separation on the basis of E and EA rosetting differed in their phenotypic composition from those separated on the basis of density or on immune complex monolayers. The E- Fc gamma- population contained few LGL and OKM1 positive cells. The E- Fc gamma+ population was made up almost entirely of LGL and OKM1 positive cells. The low density population was highly enriched in LGLs; among these the Fc gamma- cells were OKT3 positive. In contrast to the E- population the low dense Fc gamma+ cells were mainly LGLs and were OKM1 positive. Fc gamma+ subsets had less killer activity against Daudi cells. The choice of procedure for obtaining a strongly cytotoxic population depends on the needs of particular experiments. Separation on the basis of E rosetting gave lower cell (62%) and cytotoxic (43%) recovery and required about twice the amount of blood and twice the time, as compared with the other 2 procedures. The cell fractions obtained this way allowed characterization of several phenotypically different active populations and showed a difference in cytotoxic potential against K562 and Daudi cells. Density fractionation isolated a highly cytotoxic subset with LGL morphology but this population was still heterogeneous phenotypically. With regard to enrichment of NK activity, the immune complex monolayer attachment method was the most efficient for total cell recovery and for the time taken to perform it.