ABPC 48 cross-reactive idiotopes in BALB/c mice. Natural and levan-induced expression.

Abstract

The existence of a functional idiotypic network was postulated by Jerne (1) nearly one decade ago. Many experiments do indeed prove the feasibility of idiotypic manipulations of the immune system (see reference 2 for a review of this topic). It still remains to be established however, that idiotype-antiidiotype interactions play a major role in the ontogenesis of the immune system and that such interactions control its steady state. Information on these points may be gained from the characterization of idiotypes expressed in mice during the natural immunization event, as compared to those triggered by deliberate immunization with known antigens.Anti-levan response in BALB/c mice allows such an analysis. Bacterial levan is considered one of the most common natural antigens and the anti-levan immune response has been extensively analyzed by Lieberman et al. (3). Bacterial levan is a polyfructosan with/32-I and ~2-6 linkages. Bona et al. (4) have shown that the anti-/32-6 polyfructosan response may be elicited by immunization of young mice (from age 1 or 2 wk up) in contrast to the anti-/32-1 polyfructosan (anti-inulin) response, which can be elicited later in ontogeny. The idiotypes associated with anti-132-6 antibodies in BALB/c include two myeloma proteins, ABPC48 and UPCI0 which we have shown in a previous study (5) to share idiotypic determinants. The obtaining of a battery of monoclonal syngeneic antiidiotypic antibodies permits us to perform very sensitive binding assays specific for one chosen idiotope. 1 As shown here, the analysis of the immune response in adult BALB/c mice injected with levan reveals that ABPC48 idiotopes contribute to this response. Information on the idiotypic pattern of a natural immunization was also gained when ABPC48 idiotype expression and anti-levan titer were compared in young BALB/c mice immunized with bacterial levan and in nonimmunized mice. Material and MethodsMice. BALB/c mice were purchased at the breeding Center of the Centre National de la Recherche Scientifique (CNRS, Orleans, France) and grown in our own animal facilities.Antigens. Bacterial levan of Bacillus subtilis origin (polyfructosan with/32-1 and ~2-6 linkages) of several molecular weights (2 × 107, 2 × 10 ~ and 5 × 104), plant levan (mol wtWe shall refer to an idiotope as the structural element that participates in the binding of one given idiotype to one given monoclonal antiidiotypic antibody. Idiotopes are likely to be overlapping regions on the variable domain of an immunoglobulin rather than ponctual determinants (6). 872J. ExP. MED.