Characterization of monoclonal antibodies recognizing immunoglobulin kappaand lambda chains in pigs by flow cytometry

The existence of two types of the immunoglobulin (Ig) light chain in pigs w as documented > 30 years ago and has been confirmed by the cloning of porci ne light chain genes homologous to human and murine Ig kappa (Ig kappa) and Ig lambda (Ig lambda). However, immunochemical reagents defining these two light chain isotypes have not been characterized. Here, we show that rabbi t antisera specific for human Ig kappa and Ig lambda and certain anti-porci ne light chain monoclonal antibodies (mAb) are useful in distinguishing lig ht chain isotypes by flow cytometry (FCM). Porcine B cell lines L23 and L35 stained positive only with anti-human Ig lambda antiserum and were negativ e when tested using anti-human Ig kappa antiserum. While mAbs K139.3E1, 1G6 and 27.7.1 also tested positive on these cell lines, mAb 27.2.1 did not. T herefore, FCM was used to examine the hypothesis that K139.3E1, 1G6 and 27. 7.1 are Ig lambda -specific whereas mAb 27.2.1 recognizes the Ig kappa chai n in pigs. Double staining of peripheral blood mononuclear cells (PBMC) wit h pairs of anti-light chain mAbs and using cocktails of anti-light chain mA bs and anti-human polyclonal antiserum, confirmed this hypothesis with the exception that mAb K139.3E1 appears to recognize only a subset of Ig lambda (+) B cells in most pigs. In summary, we identified two pan-specific anti- pig Ig lambda mAbs, one anti-lambda, mAb that recognizes a lambda -light ch ain subset and one anti-pig Ig kappa mAb. (C) 2001 Elsevier Science B.V. Al l rights reserved.