Effect of diisopropylfluorophosphate on the antibody response

Abstract

The impact of the in-vivo administration of diisopropylfluorophosphate (DFP) on the antibody response in mice was examined. The antigen-specific plaque-forming cell (PFC) response of mice injected with DFP (4 mg/kg) at the time of immunization with a macrophage-dependent T-cell antigen, trinitrophenylated keyhole limpet hemocyanin (TNP-KLH) or sheep red blood cells (SRBC), was significantly depressed. In contrast, the injection of a similar dose of DFP had no effect on the PFC response of mice immunized with a macrophage-independent B-cell antigen, lipopolysaccharide (LPS). This differential effect suggests a possible detrimental effect of DFP on cells involved in antigen processing and/or presentation which are required for the antibody response to SRBC and TNP-KLH. These results, however, do not exclude T cells as a possible target and the cellular targets of DFP action remain to be established. The DFP-mediated depression of the PFC response to SRBC was still evident when DFP was given as early as 1 day before, but not 1 day after, the injection of antigen, suggesting that DFP may well affect an early event of the antibody response. For the secondary TNP-specific IgM PFC response, a significant depression was observed only when DFP was administered at the time of antigen challenge. The injection of DFP at the time of antigen priming, however, was effective in depressing the IgG, but not the IgM, PFC response. Therefore, DFP may also interfere with the generation of antigen-specific memory cells for the secondary IgG response.