PRODUCTION AND IMMUNODIAGNOSTIC APPLICATIONS OF ANTIHUMAN LIGHT-CHAINMONOCLONAL-ANTIBODIES

Hybridomas producing antihuman light chain monoclonal antibodies (MoAb s) were derived from fusion of SP2/O mouse myeloma cells with splenic lymphocytes from mice repeatedly immunized with purified kappa- and la mbda-type Bence Jones proteins representative of the major V(kappa) (V (kappaI), V(kappaII), V(kappaIII), V(kappaIV)) and V(lambda) (V(lambda I), V(lambdaII/V) V(lambdaIII), V(lambdaIV), V(lambdaVI)) subgroups or gene families. Monoclonal antibodies were obtained that had specifici ty for constant-region (C(L)) determinants common to all kappa or lamb da light chains (C(kappa) and C(lambda), respectively) as well as for variable-region (V(L)) epitopes unique to each of the V(kappa) or V(la mbda) subgroups. The capability of these reagents to recognize C(L) an d V(L) determinants on monoclonal immunoglobulin (Ig) molecules was de monstrated in fluid-phase antigen-capturing enzyme-linked immunosorben t assay (ELISA), solid-phase ELISA, and immunoblotting. In addition, t hese antilight chain MoAbs were used to establish immunocytochemically the kappa or lambda type and V(L)-subgroup nature of light chains exp ressed by the cytoplasmic Ig of monoclonal plasma cell and surface Ig of B-lymphocyte populations, respectively. These antibodies facilitate d the immunohistochemical detection and characterization of light-chai n-associated amyloid (AL amyloid) and other types of light-chain-relat ed tissue deposits. Furthermore, the anti-C(L)-specific MoAbs were use d to measure serum and urinary Igkappa and Iglambda concentrations. Qu antification of Bence Jones protein excretion, even in the presence of other urinary proteins, was possible using the highly sensitive anti- C(kappa) and anti-C(lambda) MoAbs reactive only with free light chains . The ability to identify and characterize, through the use of these a ntihuman light chain MoAbs, light-chain-related epitopes at the protei n, cellular, and tissue level has clinical importance in the diagnosis and treatment of patients with monoclonal plasma cell and related B-c ell immunoproliferative diseases.