[Monoclonal immunoglobulins in kidney transplantation. Characterisation, evolution and risk factors].

Sera from 192 consecutive HIV negative renal transplant patients with more than 6 months follow-up were investigated for monoclonal or oligoclonal immunoglobulins (mIg) by immunoelectrophoresis or immunofixation. Gammapathy was present in 25 patients (13 percent). Eleven patients had only one monoclonal band, whereas 14 had two or more bands. Sixty percent were IgG K, 29 percent IgG lambda and 11 percent IgM lambda or K. Ninety percent of these mIg did not exceed 2 g/l; mIg appeared within 2-27 months following the transplantation (mean time-lag 8 +/- 6.4 months). The mIg were often transient: 20 disappeared within 1-33 months, most of them (14) being absent after 1 year of follow-up. Some risk factors for mIg could be identified: the patient's age (a risk factor only in women); the duration of dialysis; the occurrence of prior CMV infection; treatment with cyclosporine. The persistence of mIg was characterised by one or more of the followings: high titer of mIg, EBV infection or reactivation, inability to switch from IgM to IgG CMV antibodies. No significant association was found with the hepatitis B surface antigenemia, previous infection with hepatitis C or the number of rejection episodes. In 6 patients, the clinical course was characterised by severe infection or tumours. Although long-term follow ups are not yet available, patients in whom one or more mIg have been demonstrated should be carefully followed.