Different effects of breast cancer, HIV-1 infection and chemotherapy on inducible natural immunity.

Breast cancer chemotherapy and HIV-1 viral infection (AIDS) can result in respective transient or irreversible losses of up to 40-50% of circulating lymphocytes. The relationship of lymphopenia on tumor immunosurveillance and the control of opportunistic infections has yet to be established. The objective of this study was to characterize the changes in natural killer (NK) and lymphokine activated killer (LAK) cell function associated with cytotoxic drug therapy, breast cancer and HIV-1 infection. NK and LAK activities were measured at multiple effector to target ratios. Exponential regression analysis of target cell lysis determined the maximal % target kill and the lytic potential of effector cells. Flow cytometric analysis of lymphocyte subsets in seropositive populations was performed to determine the % of NK(CD56+) cells. Taken together, our findings indicate that cytotoxic NK pool sizes increased in breast cancer patients, diminish consequent to chemotherapy. The functional capacity of individual NK and LAK cells remains intact. In contrast, the diminution of NK and LAK functional responses in HIV-1 seropositive individuals is associated with reductions in cytotoxic NK and LAK pool sizes, as well as marked reductions in cytolytic function of individual cells. Zidovudine (AZT) treatment did not affect LAK activity in HIV+ subgroups. Our findings indicate that NK and activated LAK functions are affected both by chemotherapy and disease etiology.