The presence of J chain in mesangial immune deposits of IgA nephropathy.

In order to identify polymeric IgA in the mesangial IgA deposits of 33 patients, the presence of J chains by a PAP method was investigated. In 9/27 cases of primary IgA nephropathy (PIgANP) and in 4/4 cases of Henoch-Schönlein glomerulonephritis (HSGN) J chains were absent. The remaining cases, two of them with IgA glomerulonephritis associated with alcoholic cirrhosis (ACIgAGN), were J-positive. The two groups, PIgANP J-positive and PIgANP J-negative, were compared according to clinical features. The only difference detected was the time length between the disease onset and the renal biopsy, being shorter in the negative group.