ABSTRACT: The BALB/c mouse strain represents an excellent model for studying the activation of V genes, because several myeloma proteins share the cross-reactive idiotype with antipolysaccharide antibodies of the same antigenic specificity. In addition, the majority of these antipolysaccharide antibody responses are independent of T help and, therefore, the maturation of helper T cells does not play a role in the study of these responses.
Our results, as well as those obtained by other investigators, have shown that immunization of 1-day-old mice elicits an anti-β2—6 fructosan, 384Id anti-S tranaroa LPS, and X24IdX and X24IdI antigalactan response. T15Id+ phosphocholine, IdX+ anti-Ars, and 460Id+ anti-TNP (in response to immunization with TNP-LPS and TNP-Levan) antibody responses can be induced only in 6-to 8-day-old mice. One can obtain 2.4 SSSIII Id+ of anti-SSSIII and 347Id+ antiflagellin antibody responses only in 2-week-old mice. In 4-week-old mice IdX+ anti-β2->1 fructosan was elicited, and QPC52IdX+ anti-α1-6 dextran in 3-month-old mice. These observations suggest a sequential activation of V genes during postnatal life. The theoretical and practical implications of these observations are discussed.