Tissue distribution of natural killer (NK) cells and killer (K) cells for antibody-dependent cellular cytotoxicity (ADCC), in vivo and in vitro arming experiments, the effects of Staphylococci protein A and differential susceptibility to pronase treatment of effector cells for NK and ADCC were investigated to determine whether the effector cells for NK and ADCC are the same or distinct subpopulations. NK and ADCC activities were tested by a short-term (2½ to 4 hr) 51Cr-release assay with 51Cr-labeled human myeloid cell line K562 and TNP-conjugated human B cell line SB used as target cells for NK and ADCC, respectively. In adult specific pathogen-free (SPF) miniature swine, the effector cells for NK were present only in peripheral blood and not in spleen, thymus, mesenteric lymph nodes, bone marrow, or tonsil. In contrast, the K cells for ADCC were present in spleen and bone marrow as well as in peripheral blood. There was no detectable ADCC activity among cells from thymus, mesenteric lymph nodes, or tonsil. In germfree, colostrum-deprived, immunologically “virgin” piglets, no NK activity was detected in any tissue examined including peripheral blood, spleen, thymus, lymph nodes, bone marrow, and liver. K cells for ADCC were present in bone marrow, liver, and peripheral blood. Cells from colostrum-fed newborn piglets exposed to maternal “natural” antibodies did not acquire NK activity, and ADCC activity remained unchanged, indicating that NK activity is not simply a function of arming with “natural” antibodies in vivo. In vitro incubation of immunologically “virgin” piglet cells with sera from NK-positive animals or with culture fluid of NK-positive cells did not arm NK-negative cells to become NK-positive cells. In addition, protein A-bearing Staphylococci inhibited ADCC but not NK activity. NK activity was completely abrogated by 0.1% pronase treatment; in contrast, the ADCC activity was increased by pronase treatment. When the pronase-treated cells were incubated in autologous serum, there was no recovery of NK activity. The results demonstrate that neither in vivo arming with “natural” antibodies nor in vitro-secreted antibodies are involved in NK activity, which support the presence of NK independent of antibody. These data, which show that K cells for ADCC develop early in ontogeny before the development of the effector cells for NK, that NK cells and K cells in adults have different tissue distributions, and that NK cells are not K cells armed with “natural” antibodies, suggest that the effector cells for NK and ADCC may be distinct subpopulations.
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Kim et al. (1980) studied this question.