Amyl nitrite alters human in vitro immune function

Effects on the human immune system of volatile nitrite inhalation were studied in 18 male volunteers. While nitrite inhalation decreased the absolute number of CD3+ T lymphocytes during the period of inhalation, cell numbers returned to pre-treatment levels within one week after cessation of the drug. Nitrite inhalation did not alter the percentage of CD3+, CD4+, CD8+ or CD19+ lymphocytes. Natural killer (NK) cell activity against K562 target cells was depressed by nitrite administration but returned to pre-inhalation or greater levels after nitrite discontinuation. Cell proliferation following cell activation by PHA, ConA and PWM was unaffected by amyl nitrite inhalation. We conclude that in humans inhalation of volatile nitrites causes cycles of modest immunosuppression, particularly in NK activity, followed by gradual recovery when the drug is not inhaled for several days.