Circulating monoclonal IgM lambda cryoglobulin with collagen type I affinity in vasculitis.
A previously fit 66-years-old male primarily presented symptoms compatible with Henock-Schönlein's purpura, from which he seemingly recovered. Shortly hereafter he relapsed with an IgM lambda essential monoclonal cryoglobulinemia type I, presenting a systemic, necrotizing vasculitis, with low titer of circulating immune complexes and complement consumption. Glucocorticoid treatment and plasmapheresis did not prevent an ultimately lethal course. An indirect immunoperoxidase technique showed that the cryo-IgM bound to the interstitial connective tissue corresponding to the localization of collagen type I. In addition it bound to affinity purified human procollagen type I. These results indicate, that the IgM lambda of the proband was an autoantibody with collagen type I specificity.