PAF antagonists do not modify IgE antibody production in mice.

The effect of selective PAF antagonists on the in vivo production of IgE antibodies was investigated. The anti-ovalbumin IgE antibody content was estimated by passive cutaneous anaphylactic reaction (PCA) in the plasma of Balb/c mice 10 days after immunization with ovalbumin and alum. The PAF antagonists, BN 52021 (5 mg/kg, ip), BN 50730 (20 mg/kg, po), WEB 2086 (2 mg/kg, ip) and WEB 2170 (5 mg/kg, ip) were administered 1 h before immunization and twice a day for 8 days thereafter. The effect of the antagonists on the PAF-induced vasopermeability was also assayed. In the immunized mice the level of antiovalbumin IgE antibody, estimated by PCA titer, was 1/640. The treatment with the PAF antagonists did not change this level. At the concentrations employed, the antagonists BN 50730, WEB 2086 and WEB 2170 significantly reduced the PAF-induced vascular permeability. These results suggest that PAF does not seem to have a relevant effect on the production of IgE antibodies in vivo in the system used in the present study.