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Failure of methotrexate and methylprednisolone to alter the clearance of model immune complexes
Abstract:
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.
Insights
Methotrexate (MTX) and methylprednisolone (MP) did not affect the reticuloendothelial system's clearance of immune complexes (IC) in mice. These findings suggest these drugs do not impact immunospecific clearance pathways.
Area of Science:
- Immunology
- Pharmacology
Background:
- The reticuloendothelial system (RES) plays a crucial role in clearing immune complexes (IC) from circulation.
- Understanding how common immunosuppressive drugs affect IC clearance is vital for managing autoimmune diseases.
Purpose of the Study:
- To investigate the impact of methotrexate (MTX) and methylprednisolone (MP) on the RES clearance of soluble IC.
- To determine if MTX or MP alter the efficiency of IC uptake by the RES.
Main Methods:
- BALB/C mice were treated with varying doses of MTX or MP, or saline as a control.
- Radiolabelled model IC were administered intravenously, and blood radioactivity was measured over 3 hours.
- Organ uptake of IC was quantified, correcting for residual blood content.
Main Results:
- No significant differences in IC clearance rates were observed between drug-treated groups and the control group.
- Organ uptake of IC did not differ significantly across experimental conditions.
- The administration of MTX and MP did not alter the RES-mediated clearance of soluble IC.
Conclusions:
- Methotrexate and methylprednisolone do not appear to influence the immunospecific clearance of soluble immune complexes via the RES.
- These findings suggest that the immunosuppressive effects of MTX and MP may not involve modulation of this specific clearance mechanism.