Monoclonal gammopathy after intense induction immunosuppression in renal transplant patients

OBJECTIVES.: Incidence and risk factors of post-transplant monoclonal gammopathywere studied in renal transplant patients who received theirgrafts between 1982 and 1992 (n=390 grafts). Immunoelectrophoresiswas performed at annual intervals after transplantation. RESULTS.: Forty-six cases of clonal gammopathy were detected: 35 monoclonal,11 bi- or triclonal, with a predominance of IgG and K light-chainsubtypes (IgG, 39; IgA, 3; IgM, 4; K, 35; , 19). Gammopathywas transient in 17 patients (37%). The 5-year cumulative incidenceof gammopathy was 10.7%, much higher than expected for a groupof similar age from the general population. Thirty of the 46gammopathies appeared within the first 2 years of transplantation.Gammopathy never progressed to multiple myeloma during follow-up(median 1 year; (range 0–10)); one patient subsequentlydeveloped Kaposi sarcoma. The 2-year incidence of gammopathywas much higher in patients transplanted in 1989–1991(23/142) than in 1982–1988 (7/248) (P<0.0001). Thiscoincided with the use of quadruple induction immunosuppression(cyclosporin A+azathioprine+prednisone plus either ATG-Fresenius(ATG-F) or OKT3) since 1989. The risk for acquiring gammopathywithin 2 years of transplantation was 14.7% (95% CI 9.2, 20.3%)in patients receiving quadruple induction therapy, but only3.0% (CI 1.2, 6.1%) without such therapy (P<0.0001). Therisk for patients receiving quadruple immunosuppression withOKT3 was 24.5%, significantly greater than with ATG-F (11.8%,P<0.05). Discriminant analysis revealed that the type ofimmunosuppression, but not age or year of transplantation, wereindependent risk factors for gammopathy. CONCLUSIONS.: Monoclonal gammopathy frequently occurs after renal transplantation.Risks are higher for patients receiving quadruple inductionimmunosuppression, particularly if it includes OKT3. Follow-upof these patients is warranted for the early detection of malignanttransformation.