Monoclonal gammopathy after intense induction immunosuppression in renal transplant patients.

Objectives: Incidence and risk factors of post-transplant monoclonal gammopathy were studied in renal transplant patients who received their grafts between 1982 and 1992 (n = 390 grafts). Immunoelectrophoresis was 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 kappa light-chain subtypes (IgG, 39; IgA, 3; IgM, 4; kappa, 35; lambda, 19). Gammopathy was incidence of gammopathy was 10.7%, much higher than expected for a group of similar age from the general population. Thirty of the 46 gammopathies 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 subsequently developed Kaposi sarcoma. The 2-year incidence of gammopathy was much higher in patients transplanted in 1989-1991 (23/142) than in 1982-1988 (7/248) (P < 0.0001). This coincided 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 gammopathy within 2 years of transplantation was 14.7% (95% CI 9.2, 20.3%) in patients receiving quadruple induction therapy, but only 3.0% (CI 1.2, 6.1%) without such therapy (P < 0.0001). The risk for patients receiving quadruple immunosuppression with OKT3 was 24.5%, significantly greater than with ATG-F (11.8%, P < 0.05). Discriminant analysis revealed that the type of immunosuppression, but not age or year of transplantation, were independent risk factors for gammopathy.

Conclusion: Monoclonal gammopathy frequently occurs after renal transplantation. Risks are higher for patients receiving quadruple induction immunosuppression, particularly if it includes OKT3. Follow-up of these patients is warranted for the early detection of malignant transformation.