Immunological studies in a familial IgA nephropathy.

The hypothesis that abnormalities of immune function might occur in healthy first degree relatives of two patients with a familial IgA nephropathy was tested. After 7 days of culture, pokeweed mitogen stimulated peripheral blood mononuclear cells from the two affected members with IgA nephropathy (father and older son), as well as two other healthy sons, produced significantly more polymeric IgA than the controls. The fact that only the two patients with IgA nephropathy presented high serum levels of polymeric IgA favours the idea that a defect in the clearance of this immunoglobulin might be an important step in the appearance of this nephropathy. All the healthy members of the family had a normal OKT4+/OKT8+ cell ratio and a normal concanavalin A generated IgA suppressor cell function in contrast with the abnormalities observed in the two affected members and the previous results in a large number of patients with IgA nephropathy. These data suggest that the primary cellular abnormality might reside in B cells, being the T cell alterations observed in patients a secondary or subsequent phenomenon. These results further support the existence of genetic bases for the susceptibility to this disease.