Effects of moxalactam and cefuroxime on mitogen-stimulated human mononuclear leukocytes

The effect of moxalactam and cefuroxime on mitogen-stimulated human peripheral blood mononuclear leukocytes was studied. Mononuclear leukocytes, mitogen, and antibiotic were added to microtiter wells. Cells were cultured for 3 days, pulsed with tritiated thymidine, and then counted. Compared with control cell cultures, treated cultures showed phytohemagglutinin responsiveness to be depressed by the addition of moxalactam at concentrations of 25 to 200 micrograms/ml (P less than 0.001) and by cefuroxime at concentrations of 50 to 200 micrograms/ml (P less than 0.02 to P less than 0.01). The depressive effect on blastogenesis was less marked when concanavalin A was used. Unstimulated lymphocyte transformation responses were also depressed by both antibiotics at all concentrations (P less than 0.05). Preincubation of mononuclear leukocytes with antibiotic for 2 h, followed by washing and culturing in an antibiotic-free medium, did not depress transformation response. When antibiotic was added 24 h after mitogen, depression of response was insignificant. The data from this study suggest that two new beta-lactam antibiotics, at concentrations achievable in serum when used therapeutically, may have immunosuppressant effects. It remains to be established whether these effects are clinically important.