Development and properties of a murine monoclonal antibody to human Immunoglobulin Lambda light chain

In human, immunoglobulin (Ig) light chain comprises of two isotypes: Kappa (K) and lambda (λ) based on structural differences in their constant region. The ratio of K to λ light chains is about 3/2. Marked changes in this ratio can happen in monoclonal expansion of neoblastic B cells. Anti human light chain monoclonal antibodies (MAbs), have clinical importance in the diagnosis and immunotherapy of patients with monoclonal plasma cell and related B-cell immunoproliferative disease. This study describes the production and characterization of a MAb specific for λ light chain of human Igs. Hybridomas producing antihuman light chain MAbs were derived from fusion of mouse SP2/0 myeloma cells with Splenic lymphocytes from Balb/C mice immunized with λ light chain type of human IgG1 myeloma proteins. Fused cells were grown in hypoxanthine, aminopterine and thymidine (HAT) selective medium and cloned by limiting dilution assay. Antibody secreting cells were screened by enzyme-linked immunosorbent assay (ELISA) and the specificity of secreted MAbs was further analyzed using a panel of highly purified myeloma proteins, their fragments (Fab and Fc) and animal sera by ELISA and immunoblotting . A murine hybridoma was obtained that secretes a MAb specific for the Fab fragment of the immunizing protein and only reacts with human Igs with λ light chain type. This MAb reacts with a linear epitope located to λ light chain of human Igs as was shown by immunoblotting. This MAb could have potential implications for diagnosis and monitoring of monoclonal λ light chain diseases and treatment of related B cell tumors.

Keywords:

Monoclonal antibody , Human Immunoglobulin , ? light chain