RESUMEN
Antibody responses to kappa (kappa)-light (L) chain are absent in normal (Ckappa+/+) animals because of tolerance due to the abundance of kappa-L chains expressed on more than 95% of all B cells and serum Ig.When heterozygous kappa-sufficient (Ckappa+/-) females are bred with homozygous kappa-deficient (Ckappa-/-) males, half of their offspring will become kappa-deficient but have received kappa-L chain containing maternal Ig, mainly IgG and IgA, through placental and intestinal transmission. The kappa-containing maternal Ig persists for more than 2 months in the circulation of the offspring. Starting from weeks 15 to 20 of age, a spontaneous antibody response towards the maternal kappa-L chains can be recorded. The time of onset, as well as the magnitude of the responses differ among individuals of the same litter. Invariably, once a response has been initiated, it transits into an IgG-type of response, which upon injection with kappa-containing protein shows the features of a secondary type of immune response.
