Immunoenhancing effects of alprazolam in mice

The GABA/benzodiazepine receptor chloride channel complex has been proposed to play a modulatory role in immune function. The effects of alprazolam, a triazolobenzodiazepine with high affinity for "central" benzodiazepine receptors, were examined on several parameters of immune function in mice. Natural killer cell activity, mixed leukocyte reactivity and mitogen-induced lymphocyte proliferation were all significantly increased two hr after administration of low doses (0.02-1.0 mg/kg) of alprazolam. Twenty four hr later, similar but less robust immunoenhancing effects were observed. Higher doses of alprazolam (5-10 mg/kg) did not affect these measures of immune function. The immunoenhancing effects of alprazolam did not appear related to corticosterone levels. In contrast, vehicle injection caused a profound suppression of these immune parameters two hr later, which was no longer apparent 24 hr later. This immunosuppression appeared to correlate with a concurrent rise in serum corticosterone levels. These data support the hypothesis that the GABA/benzodiazepine receptor chloride channel complex modulates immune function. Use of low doses of alprazolam may be of potential clinical importance when immunoenhancement is required.