Autoimmune antibody positivity Anti-glomerular basement membrane-antibody positivity 2020-06-13T11:18:10Z The presence of autoantibodies in the serum that react to the glomerular basement membrane. Anti-GBM-antibody positivity Anti-GBM-antibodies are found in Goodpasture syndrome. Circulating antibodies are directed against the collagen of the part of the kidney known as the glomerular basement membrane (GBM), resulting in acute or rapidly progressive glomerulonephritis. Antibodies also attack the collagen of the air sacs of the lung (alveoli) resulting in bleeding of the lung (pulmonary hemorrhage).