Cells that mediate NK like cytotoxicity are present in the human delayed type hypersensitivity response.

By inducing delayed type hypersensitivity (DTH) responses under previously formed skin blisters we determined that cells which mediate natural killer (NK) like cytotoxicity are present in the DTH response in man. Similar levels of killing were not present in cells obtained from skin blisters not associated with positive DTH responses. The DTH response associated killer cell was found to be a mononuclear cell that had presumably undergone stimulation since it not only killed NK sensitive K-562 cells, but also NK resistant Daudi target cells.

NK cell activity and skin test antigen stimulation of NK like CMC in vitro are decreased to different degrees in pregnancy and sarcoidosis.

Peripheral blood mononuclear cells (PBMNC) isolated from normal subjects, pregnant women and patients with sarcoidosis were assayed for natural killer (NK) cell activity on day 0 and for NK like cell-mediated cytolysis (CMC) after 5 days of exposure, in vitro to Candida antigen, purified protein derivative (PPD), and human leucocyte interferon (IFN). Pregnant women and women with sarcoidosis had significantly decreased levels of NK cell activity compared to normal women. Pregnant women had the lowest mean NK cell activity. Cells from women with sarcoidosis and from pregnant women also had lower levels of killing than those from the normal women after in vitro stimulation of NK like CMC with Candida antigen, PPD and IFN. The lowest stimulations of NK like killing occurred in the cells from women with sarcoidosis. Skin test antigen stimulation of NK like CMC in vitro and the DTH response in vivo were strongly correlated for both Candida antigen and PPD in the sarcoidosis patients. There was no correlation between the level of NK cell activity in the PBMNC of sarcoid patients on day 0 and the amount of NK like CMC that was present in cells from those patients after 5 days of culture with Candida antigen, PPD or IFN. A significant correlation was found, however, between Candida antigen stimulation of NK like CMC and IFN stimulation of NK like CMC in both pregnant and sarcoid groups. Reduced NK cell activity on day 0 in a given patient thus did not necessarily indicate that skin test antigen or IFN stimulation of NK like CMC on day 5 would also be depressed. In addition, NK cell activity was often noted to be normal in patients with depressed in vitro stimulation of NK like CMC.

The skin test antigen stimulated killer (STAK) cell mediating NK like CMC is OKM1 positive and OKT3 negative.

Recently we demonstrated that candida antigen stimulated natural killer cell like cell-mediated cytolysis (NK like CMC) in peripheral blood mononuclear cells (PBMNC) isolated from normal individuals (Tartof et al., 1980). Utilizing monoclonal antibodies directed against human mononuclear cell subpopulations in conjunction with a fluorescence activated cell sorter (FACS) we determined that, similar to the previously described NK cell, the skin test antigen stimulated killer (STAK) cell is a larger OKM1 positive, OKT3 negative cell. We obtained similar results using two different skin test antigens. Thus, stimulation of NK like CMC in PBMNC by skin test antigens probably represents activation of NK or NK like cells.

Stimulation of NK-like CMC by skin test antigens in vitro is depressed in patients with SLE.

Peripheral blood mononuclear cells isolated from patients with systemic lupus erythematosus (SLE) developed lower levels of skin test antigen stimulated natural killer cell like cell-mediated cytolysis (NK-like CMC) than did similar cells from age and sex matched non-SLE volunteers. When the subjects were grouped according to disease activity the cells from the patients with mild disease activity developed lower levels of NK-like CMC than did those from the non-SLE control subjects. The cells isolated from SLE patients who had moderate to severely active disease developed little if any NK-like CMC after exposure to various skin test antigens. Greatly decreased skin test antigen stimulation of NK-like CMC in the cells from the SLE patients with more active disease did not appear to be due to therapy with corticosteroids or to a suppressor effect on this response by monocytes present in the peripheral blood mononuclear cell populations.

Small nuclear ribonucleoprotein complexes of Drosophila melanogaster.

We report here on the isolation and characterization of small nuclear ribonucleoproteins (snRNPs) and corresponding small nuclear RNA (snRNA) species from nuclei of Drosophila melanogaster. Velocity sedimentation in sucrose gradients was used to partially fractionate the RNPs; analysis of fractions so obtained suggests that, in general, one snRNP contains one snRNA. At least 11 species of snRNA are present in Drosophila nuclei; among them we identify a potential mammalian U1 homolog based on sequence homology. Autoimmune antiserum designated anti-Sm from patients with systemic lupus erythematosus recognizes nuclear antigens in Drosophila and precipitates seven species of snRNPs. The antigens in HeLa and Drosophila nuclei recognized by anti-Sm antibodies have been identified and compared. Anti-Sm antibodies at least bind to a 26,000-dalton polypeptide in HeLa extracts and to two polypeptides, one of 18,000 daltons and one of 26,000 daltons, in Drosophila extracts. This suggests that the 26,000-dalton polypeptide is an evolutionarily conserved antigenic component of Drosophila and HeLa snRNPs.

Studies on stimulation of cell-mediated cytotoxicity by skin test antigens. I. Candida antigen stimulation of cell-mediated cytotoxicity in vitro correlated with the skin test response to candida antigen in vivo.

The magnitude of the skin test response in a group of normal volunteers to intradermal Candida antigen correlated closely with the level of cytolytic activity stimulated by Candida antigen in vitro in the peripheral blood lymphocytes from those same individuals. The cytolytic activity stimulated by Candida antigen was cell mediated, and cold target inhibition studies demonstrated that Candida antigen-stimulated effector cells were capable of cross-species (i.e., nonspecific) killing. Analysis of the Candida antigen-induced effector cell population for various cell markers did not enable absolute identification of the cell responsible for the killing. The findings in this study indicate that the stimulation of cell-mediated cytolysis by Candida antigen may be related to the delayed-type hypersensitivity response produced by the same antigen.

Kinetics of CTL induction by concanavalin A.

Induction of maximal CTL activity was achieved within 12 hr of exposure to Con A in vitro in various mouse lymphoid cell populations. These included spleen cells from normal unsensitized mice, spleen cells from mice previously immunized with alloantigen, and mouse spleen cells exposed to alloantigen in long-term mixed leukocyte culture (LTMLC). Although induction of maximal incorporation of tritiated thymidine was accomplished within this same period in the cells obtained from LTMLC, a much longer period of Con A exposure (greater than 24 hr) was required for freshly prepared spleen cells from normal or previously immunized mice. These findings indicate that the increased tritiated thymidine uptake induced in freshly prepared spleen cells on continued exposure to Con A beyond 12 hr is not associated with the development of cytolytic activity, and that it probably represents stimulation of subpopulations no longer present in the LTMLC population where positive selection for cells responsive to cellular alloantigens has taken place.

Immunologically specific cytolytic activity induced in long-term mixed leukocyte culture cells by concanavalin A.

Stimulation of cells from long-term primary MLC with Con A resulted in the generation of CTL activity comparable in magnitude to that induced by reexposure of the cells to the original stimulating cellular antigen. CTL generated by stimulation of long-term MLC cells with ConA had lytic activity specific for the original stimulating alloantigen used in primary MLC. The pattern of stimulation of long-term MLC cells with Con A differed from that of restimulation with alloantigen in that there was no detectable CTL activity the first 24 hr after Con A stimulation and the peak lytic activity occurred later. Unlike restimulation with alloantigen early lytic activity after Con A stimulation was dependent on DNA synthesis. PHA also proved to be an effective agent for stimulating cytolytic activity in long-term MLC cells. The response to PHA was comparable in magnitude to that generated by Con A. Stimulation of long-term MLC cells with T cell mitogens gave decreased cell recoveries relative to restimulation with alloantigen, however, the lytic activity per cells recovered was generally greater in the mitogen-stimulated cultures.