HAEMOPHILUS-PARAINFLUENZAE ANTIGEN AND ANTIBODY IN RENAL BIOPSY SAMPLES AND SERUM OF PATIENTS WITH IGA NEPHROPATHY

IgA nephropathy may be associated with colonisation with Haemophilus p arainfluenzae. In patients with glomerular diseases, we examined renal -biopsy specimens for presence of bacterial antigen by immunofluoresce nce microscopy with rabbit antiserum against H parainfluenzae, and by enzyme-linked immunosorbent assay looked for IgA antibody against H pa rainfluenzae in patient sera. The rabbit antiserum recognised by immun oblotting four components of H parainfluenzae outer membranes (OMHP) o f molecular weights 19.5, 30, 33, and 40 5 kDa. All 44 patients with I gA nephropathy and 2 of 3 9 patients with other glomerular diseases sh owed mesangial deposition of OMHP antigens (p<0.001). Patients with Ig A nephropathy had significantly more IgA antibody against H parainflue nzae than did patients with other glomerular diseases. IgA antibody in the sera of patients with IgA nephropathy recognised by immunoblottin g the same four components of OMHP as recognised by rabbit antiserum. Glomerular deposition of OMHP antigens and the presence of IgA antibod y against OMHP in patients with IgA nephropathy suggest that H parainf luenzae has a role in the aetiology of this disease.