Impairment of helper T-cell function and lymphokine-activated killer cytotoxicity following severe head injury

✓ Infection is a major complication of severe head injury, occurring in 50% to 75% of patients who survive to hospitalization. Previous investigations of immune activity following head injury have demonstrated suppression of helper T-cell activation. In this study, the in vitro production of interferon-gamma (INF-γ), interleukin-1 (IL-1), and interleukin-2 (IL-2) was determined in 25 head-injured patients following incubation of peripheral blood lymphocytes (PBL's) with the lymphocyte mitogen phytohemagglutinin (PHA). In order to elucidate the functional status of cellular cytotoxicity, lymphokine-activated killer (LAK) cell cytotoxicity assays were performed both prior to and following incubation of PBL's with IL-2 in five patients with severe head injury. The production of INF-γ and IL-2 by PHA-stimulated PBL's was maximally depressed within 24 hours of injury (p < 0.001 for INF-γ, p = 0.035 for IL-2) and partially normalized within 21 days of injury. There was no change in the production of IL-1. When ...