Shunt nephritis: the nature of the serum cryoglobulins and their relation to the complement profile.

The serum complement profiles of four patients with shunt nephritis indicated classical pathway activation of the complement system. The presence of mixed cryoglobulins was correlated with disease activity and the cryoglobulins were shown to be complement reactive. Antisera to two of the cryoglobulins recognized antigens of the infecting organism, and a specific bacterial antibody was identified in one cryoglobulin, giveing evidence that the cryoglobulins contained immune complexes. Bacterial antibody without detectable antigen was demonstrable in the sera indicating antibody excess. Renal morphology demonstrated mesangial proliferation and interposition with subendothelial and mesangial deposits. Parallels are drawn with active lupus nephritis.