Effect of ciprofloxacin on human lymphocytes--laboratory studies

4-Quinolones affect mammalian cellular functions in vitro in several ways. Inhibition of cell proliferation differ widely among 4-quinolones. Ciprofloxacin is one of the most antiproliferative inhibiting cell growth with about 30% at 20 mg/l. Genotoxicity tests with 4-quinolones are probably "false" positive due to an increased [3H]-thymidine uptake not related to DNA damage. Ciprofloxacin at 10 mg/l and up causes significant DNA strand breaks which seemingly are quickly repaired and not causing mutations or cancerogenesis. Ciprofloxacin at 5 mg/l inhibits immunoglobulin production but the growth factor interleukin 2 (IL-2) is increased by 4-quinolones at the same concentration and hyperinduced at higher concentrations. Thus the effects are very contradictory. Increased IL-2 may contribute to CNS side effects.