Increase of IgM-bearing peripheral blood lymphocytes in patients with idiopathic membranoproliferative glomerulonephritis (MPGN) and their family members.

The number of Immunoglobulin-bearing and E-rosette forming peripheral blood lymphocytes, serum levels of immunoglobulins and complement and urinary sediments were examined in patients with idiopathic membranoproliferative glomerulonephritis (MPGN) and their immediate family to determine if familial factors might be related to the development of this disease. Twenty-five patients with MPGN (22 Type I and 3 Type II), 24 family members and 36 age-matched healthy persons were examined. All patients showed an increase in the number of IgM-bearing peripheral blood lymphocytes. All families showed some members with increased numbers of IgM-bearing lymphocytes. There were no significant correlations between the numbers of IgM-bearing peripheral blood lymphocytes and the levels of serum immunoglobulins and complement.