Primary Structure of the Human VkII Regions Elicited by Haemophilus influenzae Type b Polysaccharide Vaccines; The J Gene Usage Is Restricted in Child Antibodies Using the A2 Gene

The Haemophilus influenzae type b (Hib) has been a major cause of bacterial meningitis in children who are less than two years old. The variable (V) region repertoire of adult Caucasian antibodies (Abs) to Hib polysaccharide (PS) has been characterized well. The majority of adult antibodies against Hib uses VL that is derived from the Vk gene A2 and have arginine at the N region. In order to explore the possibility those antibody responses to Hib-PS is variable in various age groups, we examined the VL regions of the antibodies to Hib-PS in Korean adults and children. We immunized Korean adults (n = 8) and children (n = 39) with Hib tetanus conjugated vaccines, isolated RNAs from the peripheral lymphocytes, and amplified the A2-derived VL regions by RT-PCR. The PCR products were subcloned and sequenced. Forty-seven out of 54 independent clones from children used the $J{\kappa}2$, or $J{\kappa}3$ gene in preference. The adults, however, used all of the $J{\kappa}$ genes evenly. With respect to the amino acid sequences of variable regions, adult $A2-J{\kappa}$ recombinants have a germline sequence. But, the 76th codon (AGC) of child $A2-J{\kappa}2$ recombinants was substituted with CGC (arginine) in most cases (88 %) and 77 percent of child clones using the $A2-J{\kappa}3$ genes have isoleucine-109 at the junction of $J{\kappa}-C{\kappa}$ instead of threonine that is found in a germline sequence. These results suggest that the mechanism of antibody production in young children is different from that of adults.