Detection of native and denatured DNA antibody forming cells by the enzyme-linked immunospot assay. A clinical study of (New Zealand black x New Zealand white)F1 mice

Abstract

A new method for measuring DNA antibody forming cells (DNA-AFC) using the enzyme-linked immunospot (ELISPOT) assay is described. This method uses enzyme-linked immunosorbent assay (ELISA) techniques applied to cells cultured on DNA-coated plates, which allows visual quantitation of spots representing imprints of specific antibodies from DNA-AFC. Specificity for DNA was confirmed by inhibition studies and lack of reactivity by anti-lysozyme hybridomas. Isotypes of IgG and IgM can be measured using the appropriate antisera in the assay. A study of 16 female (New Zealand black x New Zealand white)F1 ([NZB x NZW]F1) female mice showed significant correlation between age, rising blood urea nitrogen levels, and increasing proteinuria and increasing numbers of DNA-AFC. In contrast, the correlation between circulating antibodies to DNA (ELISA method) and clinical parameters of nephritis was not significant. Both the native DNA ELISPOT and the native DNA ELISA had similar significant linear correlations with age. This is the first report of use of the ELISPOT assay for measurement of DNA-AFC. The DNA-AFC measured by this method were specific and correlated with the presence of clinical nephritis in (NZB x NZW)F1 mice. This method should allow further study on the regulation of DNA-AFC in vitro and in vivo, and will be useful in the investigation of DNA-AFC and cellular mechanisms of autoimmunity.