Leu-11+ lymphocytes with natural killer (NK) activity are precursors of recombinant @entity1199 ( XXXX )-induced activated killer (AK) cells.

@entity1 @entity4755 @entity5041 @entity1199 @entity694
Precursors of activated killer (AK) cells cytotoxic for @entity1 noncultured metastatic melanoma and @entity694 were characterized. These cells required 3 days incubation with recombinant @entity1199 ( @entity5041 ) and DNA synthesis for the induction of AK activity. Both negative and positive cell purification methods were used to identify the subpopulation of cells containing AK precursors. By complement-mediated cell depletion studies, AK precursors were largely present in the Leu-11+ fraction, and to a much lesser extent in the @entity4755 + and Leu-2a+ fractions; they were absent in Leu-3a+ and Leu-4+ cells. Lymphocyte subpopulations were then purified with a cell sorter to positively select for the subset containing AK precursors. Leu-11+ cells had the highest level of AK activity and proliferative response when cultured for 3 days with @entity5041 as well as the highest level of NK activity before culture. @entity4755 + cells had neither AK activity nor a proliferative response when cultured with @entity5041 , although they still possessed high NK activity. The same levels of AK and NK activity were found in Leu-2a+ and Leu-2a- fractions, but both activities were absent among Leu-4+ and Leu-3a+ cells. Further fractionation with a two-step sorting technique showed that the highest AK activity resided in the @entity4755 -Leu-11+ cell fraction. Morphologically, this subfraction was granular lymphocytes. Titration experiments or @entity5041 -responsive cells showed that the number of cells required to achieve a comparable level of @entity5041 proliferative response were as follows: 35 X 10(3) cells from unseparated PBL, 10 X 10(3) cells from Leu-11+ cells, 3.3 X 10(3) from @entity4755 -Leu-11+ cells, and 640 X 10(3) cells from @entity4755 + cells. These results indicate that the lymphocyte subpopulation that proliferates in the presence of @entity5041 and then develops AK activity was a subpopulation of Leu-11+ granular lymphocytes, which also possessed the highest NK activity. These Leu-11+ cells lacked the antigens defined by the @entity4755 , Leu-3a, or Leu-4 antibodies. Although @entity4755 + cells did not respond to @entity5041 by themselves, they may play a role in the induction of AK activity.
