HALOTHANE INHIBITS T-CELL PROLIFERATION AND INTERLEUKIN-2 RECEPTOR EXPRESSION IN RATS

In order to determine the effects of halothane on rat cell-mediated im mune function, rats were exposed to 1% halothane for up to 5 hours. Im mediately, 24 hours or 48 hours following anesthesia, rat lymphocytes from the spleen were analyzed for their ability to respond to the mito gens phytohemagglutinin (PHA), pokeweed mitogen (PWM), concanavalin A (ConA) and lipopolysaccharide (LPS). In addition, percentages of lymph ocyte subpopulations in the spleen were assessed as well as ability of the lymphocytes to express specific receptors. Extended periods of ha lothane anesthesia (5 hours) suppressed the ability of the lymphocytes to respond to the mitogen PHA immediately following anesthesia. Twent y-four hours later, proliferative responses to the mitogens PHA, PWM a nd ConA were significantly reduced. However, by 48 hours following tre atment, proliferative responses were normal. Halothane did not alter p roliferative responses to the mitogen LPS. Prolonged anesthesia (5 hou rs) also increased the percentage of T and CD8(+) (cytotoxic) lymphocy tes in the spleen, although for less than 24 hours. The ability of T l ymphocytes to express both the CD8 and CD25 (IL-2) receptors in respon se to PHA were suppressed. These results suggest that halothane suppre sses rat T cell function, perhaps through suppression of IL-2 receptor expression.