Anti-glomerular basement membrane antibody

Anti-glomerular basement membrane antibody is a reticular structure composed of inner and outer transparent layers of glomerular capillaries and an intermediate dense layer, mainly composed of glycoproteins. The most common method for detecting GBM antibodies is the IIF method (indirect immunofluorescence method) with kidney tissue as the antigen. Its fluorescence characteristic is that it shows typical petal-like, spot-like, or granular staining at the glomerular basement membrane. IIF method can produce false positive results. ELISA and radioimmunoassay using collagenase-digested crude GBM as an antigen are also available, and its sensitivity and specificity depend on the purity of the antigen. It is commonly used in clinical practice to detect indirect immunofluorescence. Principle of indirect immunofluorescence method: Label fluorescein on the corresponding antibody and directly react with the corresponding antigen. In the first step, add an unknown unlabeled antibody (sample to be tested) to a known antigen sample, and incubate at 37 ° C for 30 minutes in a wet box to fully bind the antigen and antibody, and then wash to remove the unbound antibody. In the second step, add fluorescently labeled antiglobulin antibodies or anti-IgG and IgM antibodies. If an antigen-antibody reaction occurs in the first step, the labeled antiglobulin antibody will further bind to the antigen-bound antibody, which can identify unknown antibodies.