Comparison of polyclonal and monoclonal antibodies in determination of glomerular deposits of hepatitis B virus antigens in hepatitis B virus-associated glomerulonephritides

Abstract

The nature of hepatitis B virus (HBV) antigens in HBV-associated glomerulonephritides was investigated in 7 hepatitis B surface antigen (HBsAg) carriers with membranous nephropathy, 16 HBsAg carriers with mesangial IgA nephropathy, and 1 HBsAg carrier with a mixed picture of membranous and IgA nephropathies. Consecutive frozen sections of renal biopsy specimens were stained with polyclonal and monoclonal antibodies against HBV antigens. Glomerular capillary deposits of HBeAg and HBcAg were detected in 66% and 57% of renal biopsies from HBsAg carriers with membranous nephropathy by monoclonal and polyclonal antibodies, respectively. The discrepancy in the immunofluorescence findings resulted from the cross-reactivity of the polyclonal anti-HBcAg antiserum because it contains both anti-HBcAg and anti-HBeAg activities. Mesangial deposits of HBsAg were detected in 40% and 21% of renal biopsies from HBsAg carriers with mesangial IgA nephropathy by polyclonal and monoclonal antibodies, respectively. The authors' study confirms that HBeAg is the predominant HBV antigen deposited in HBV-associated membranous nephropathy, and glomerular HBsAg deposits are detected in some HBsAg carrier with mesangial IgA nephropathy. Careful testing and evaluation of each antibody are necessary to prevent misinterpretation.