Structural polymorphism of V kappa 21 E and V kappa 21 D gene products in laboratory mice

The aim of the present work was to study structural polymorphism of V kappa genes products. To this end we isolated immunoglobulins expressing the V kappa 21 D and V kappa 21 E gene products from the normal sera of several inbred strains of mice using a monoclonal antibody that selectively recognizes V kappa 21 D and V kappa 21 E subgroups. Analysis of the isoelectric focusing pattern of the light chain of these immunoglobulins revealed the existence of 3 clearly different phenotypes. The first one is shared by most inbred strains of mice, the second one is expressed by C58/J, AKR and PL/J and the third one defines V kappa 21 D-E light chains of SJL and SJA mice. Genetic analysis revealed that the locus controlling V kappa 21 D-E chain structure is closely linked to the Ly2-3 and to the Ig Kappa-Ef1 loci. Finally, using recombinant mouse strains, we could also order V kappa 21 D-E genes with respect to the known loci affecting V kappa polymorphism. Taken together our data argue against the possibility that the polymorphism observed results from strain-specific expression of V kappa genes common to all mice, but rather suggest that different allelic form of the same V kappa gene subgroup exist in different strains.