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.