Failure of methotrexate and methylprednisolone to alter the clearance of model immune complexes.

We evaluated the effect of methotrexate (MTX) and methylprednisolone (MP) on reticuloendothelial system (RES) clearance of soluble model immune complexes (IC) in BALB/C mice. MTX was administered by intraperitoneal route either as a single dose (0.5 mg/kg) or as 10 alternate day doses (0.1 or 0.5 mg/kg), MP as a single intravenous (IV) bolus (50 mg/kg) with normal saline used as a control. Mice were then injected IV with radiolabelled IgG anti-DNP covalently crosslinked IC. Blood radioactivity was measured over a 3 h period at which time organ uptake, corrected for blood contamination, was determined. Clearance curves for each mouse were derived using the Marquardt-Levenberg curve fitting method. No significant differences in IC clearance or organ uptake were found between drug and control groups at any drug dose or time period. Our findings argue against an influence of MP and MTX on immunospecific clearance of soluble IC.