The influence of antibiotics on the immune system. II. Modulation of fish leukocyte responses in culture.

We report the immunomodulating effect of two tetracycline analogues (oxytetracycline and doxycycline) on mitogenic and allogeneic stimulation of carp (Cyprinus carpio) leukocytes in vitro. Both drugs interfered with 3H-thymidine incorporation into the DNA of phytohaemagglutinin-stimulated pronephric leukocytes in a dose-dependent manner. Low concentrations of oxytetracycline delayed the mitogenic response, but did not reduce it. In addition, several other antibiotics were tested for their possible interference with blastogenesis.