Effect of anti-inflammatory agents on the haemorrhagic response of mouse skin to Bordetella pertussis heat-labile toxin.

Bordetella pertussis heat-labile toxin (HLT) was assayed by the haemorrhagic response produced by subcutaneous injection into weaned mice. Young mice, 3-5 weeks old of either sex, were highly responsive but they became resistant to HLT as they matured. Two anti-inflammatory agents, prednisolone and meclofenamate, inhibited the skin reactions in young mice. When given intraperitoneally, prednisolone was most inhibitory if it was injected just before, or at the same time as, HLT challenge. Prednisolone given 3 h after challenge, when the skin reactions had started to develop, did not significantly attenuate the final response. Both drugs were even more effective when mixed with the HLT challenge and injected subcutaneously. These findings are discussed in relation to the possible mechanism of action of HLT and to the reported beneficial effects of corticosteroids in the treatment of whooping cough.