Effects of high-dose i.v. steroid (pulse) therapy on acute serum sickness in rabbits.

We investigated the effect of high doses (50 mg/kg/day) of i.v. methylprednisolone ("pulses") on a model of acute serum sickness in rabbits, using bovine serum albumen as antigen and endotoxin as an adjuvant. The pulses were given on 2 consecutive days at one of the following times during antigen elimination: Days 1 and 2, Days 5 and 6, and Days 8 and 9. Methylprednisolone did not alter antibody production, or the size of circulating immune complexes. Pulses given at any period inhibited the fibrinoid necrosis associated with arteritis, but did not otherwise lessen the histopathological changes. Pulses given on Days 1 and 2 or at the end of immune elimination on Days 8 and 9 increased proteinuria and haematuria, and tended to increase histopathological changes, whereas pulses given at the onset of immune elimination on Days 5 and 6 in contrast reduced haematuria, but had a variable effect on proteinuria and organ damage. In this model high-dose steroids produced no consistent amelioration of the disease, apart from reduced fibrinoid necrosis, and at some times there was a tendency for the disease to be exacerbated.