| Abstract: | The ratio of ? and λ chains of immunoglobulins varies significantly from one species to another. It has previously been thought that λ was only type expressed in mink. We tested mink immunoglobulin light chains using two monoclonal antibodies G80 and G88. It has been shown that G80 and G88 specifically recognize two antigenically different subpopulations of the light chains. Immunochemical analysis of these subpopulations separated by affinity chromatography suggested that they represent λ and ? types of light chains, respectively. Screening of a mink cDNA library with monoclonal antibody G88 resulted in the isolation of clone pIGK-1 containing ? chain-encoding sequence. The cDNA insert of pIGK-1 included most of the V segment, as well as the J, C and 3′ untranslated sequences. Mink V? sequence shown the highest homology with the human V?II subgroup genes (76-79%). Mink C? sequence was 53-63% homologous to C? of other species. The striking feature of mink C? chain is the presence of glutamine in the C-terminal position. Southern blot analysis suggested that mink haploid genome has one C? gene and multiple V? genes. The ?: λ chain ratio in the 12 minks studied was, on the average, 46:54. The same ratio was observed for the ?- and X-producing cells in the mesenteric lymph nodes. The five previously identified mink light chain allotypes were assigned to the λ chains, thereby confirming that λ chains in this species are additionally subdivided into several subtypes. |
