Natural killer cell defects resulting from thermal injury

Peripheral blood mononuclear lymphocytes (PBL) from thermal injury patients were examined for their ability to mediate spontaneous (NK) cytotoxic activity against K.562 tumor cells. NK cell numbers were quantitated in burn patients using the fluorescein isothiocyanate-conjugated monoclonal antibody Leu-7 and an Ortho cell sorter. NK activity of burn patients was only 30% of control levels. Thus, at a 50:1 effector:target cell ratio, burn patients' PBL gave a mean of 18% killing as compared to 60% killing mediated by control PBL (14 individuals). Pretreatment of PBL with interferon-γ or interferon-α enhanced NK activity of normal PBL but had no effect on the NK activity of PBL from burn patients. The number of cells bearing antigen recognized by Leu-7 was variable in burn patients, with some patients having decreased (<5%), normal (8-10%), or elevated (20-40%) numbers of Leu-7 bearing PBL. No differences were observed in the total numbers of PBL in burn patients when compared to control individuals. These results indicate that NK activity does not correlate with the percentage of Leu-7 bearing cells present in PBL and that the inability of thermal injury patients to mediate normal NK function may contribute to their susceptibilities to viral infections.