Blocking glomerular immunoglobulin deposits in a mouse model of lupus nephritis on indirect immunofluorescence with the use of Fab fragments.

One of the most characterized models of murine lupus nephritis is the [NZB×NZW] F1 female hybrid. Extended glomerular IgG deposits may pose an obstacle in studying molecules of interest via indirect immunofluorescence due to secondary antibodies non-specific binding to deposited IgG molecules. Application of Fab fragments may mitigate non-specific interactions in this mouse model. Specifically we provide evidence that blocking paratopic interactions of secondary antibodies with indigenous glomerular IgG deposits is possible. However the blocking effect seems to be related to the species used for secondary antibody production. Increased secondary antibody host species homology with the mouse could make blocking of non-specific binding via the use of Fab fragments impossible in this mouse model.