Halothane inhibits T cell proliferation and interleukin-2 receptor expression in rats.

In order to determine the effects of halothane on rat cell-mediated immune function, rats were exposed to 1% halothane for up to 5 hours. Immediately, 24 hours or 48 hours following anesthesia, rat lymphocytes from the spleen were analyzed for their ability to respond to the mitogens phytohemagglutinin (PHA), pokeweed mitogen (PWM), concanavalin A (ConA) and lipopolysaccharide (LPS). In addition, percentages of lymphocyte subpopulations in the spleen were assessed as well as ability of the lymphocytes to express specific receptors. Extended periods of halothane anesthesia (5 hours) suppressed the ability of the lymphocytes to respond to the mitogen PHA immediately following anesthesia. Twenty-four hours later, proliferative responses to the mitogens PHA, PWM and ConA were significantly reduced. However, by 48 hours following treatment, proliferative responses were normal. Halothane did not alter proliferative responses to the mitogen LPS. Prolonged anesthesia (5 hours) also increased the percentage of T and CD8+ (cytotoxic) lymphocytes in the spleen, although for less than 24 hours. The ability of T lymphocytes to express both the CD8 and CD25 (IL-2) receptors in response to PHA were suppressed. These results suggest that halothane suppresses rat T cell function, perhaps through suppression of IL-2 receptor expression.