A Rabbit Family of Restricted High Responders to the Streptococcal Group a-Variant Polysaccharide

Abstract

Immunization of rabbits and inbred mouse strains with streptococcal vaccines may induce the production of high concentrations of group-specific antibodies that not infrequently show a considerable reduction in molecular heterogeneity (1, 2). Genetically, the degree of heterogeneity and the magnitude of the immune response to the streptococcal Group A and C polysaccharides appear to be independent variables (3). In addition, selective breeding for restricted antibodies is associated with limited idiotypic variability (4)3 Similar studies were now extended to the streptococcal Group A-variant polysaccharide as an antigen that chemically and serologically constitutes the backbone of the Groups A and C carbohydrates (5, 6). A random and a related group of rabbits were used for antibody production. The d a t a suggest that immune responsiveness to the A-variant polysaccharide is also controlled b y genetic factors that again influence the magnitude and the degree of restriction as independent variables. These systems appear to be different from the situation where the pneumococcal Types I I I and V I I I antigens were used for immunization (7,8), although recently suggestive evidence is at hand that in this latter situation genetic factors may be operative as well. 2 Materials and MethodsThe major source of rabbits was the closed colony of the Statens Serum Institute, Copenhagen. A second group of rabbits consisted of progeny bred for high and restricted response to the Group C polysaccharide (3). They all originated from one breeding pair 3 (9).Vaccines from Group A-variant, strain A486 var. M--, and Group C, strain C74, streptococci were prepared as previously described (9). The group polysaccharide concentration 1 Braun, D. G., and A. S. Kelus. 1973. Idiotypic specificity of rabbit antibodies to streptococcal group-polysaccharides.

Antibody response of rabbit blood lymphocytes in vitro. Kinetics, clone size, and clonotype analysis in response to streptococcal group polysaccharide antigens.

“…This was done on gels reduced in length to one-third of the regular polyacrylamide thin-layer gels. Pools of microculture supernates and supernates from 1-ml cultures were assayed on regular IEF plates (5,10). For this, pools of microculture supernates and supernates of 1-ml cultures were concentrated 20-50-fold.…”

“…Analysis of clonotypes produced in cultures was performed by analytical isoelectric focusing (IEF) followed by overlaying with [~SI]Av-CHO, washing, and autoradiography (5,10). When single microculture supernates were assayed IEF analysis of high sensitivity, but lower resolving power, was used.…”

Specific and Cross-Reactive Activation of Rabbit Peripheral Blood Lymphocytes by Streptococcal Vaccines

“…Determinants of antigenic molecules have recently been made responsible for the difference observed in genetically controlled regulation of immune responses [25]. In fact, rabbits K33-380 and K40-512 were of common genetic background while K20-232 was from a different colony [5], Hence, differences augmented by the observed cross-stimulation may be evidence for different dictionaries of receptor molecules expressed by the responding lymphocytes. It will be intriguing to find out whether these differences relate to the heritable differences of antibody variable regions demon strated for this system both by serology -idiotypy [2,13,18] -and amino acid sequences of the light chains [4,6].…”

“…All 3 had been previously hyperimmunized with an equal dose of strepto coccal group A-variant (strain A486 variant, M-) vaccines, and they had produced 10-30 mg/ml of group-specific antibody at the peak of the response [5]. A fourth rabbit had been immunized first with A486 variant (M-) vaccine, and 6 months later with a group A streptococcal vaccine (strain J17A4).…”

“…In this study 3 rabbits from a selectively bred colony of restricted high responders were used [5], These rabbits originated from two independent, genetically unrelated colonies. All 3 had been previously hyperimmunized with an equal dose of strepto coccal group A-variant (strain A486 variant, M-) vaccines, and they had produced 10-30 mg/ml of group-specific antibody at the peak of the response [5].…”