CHARACTERIZATION OF ALLOTYPE A11 IN RABBITS - A SPECIFICITY DETECTED BY AGGLUTINATION

Inhibition of agglutination techniques were used to characterize a new allotypic determinant, A11, of rabbit immunoglobulin. Agglutinator antiserum specific for the A11 determinant was used to agglutinate rabbit type F erythrocytes sensitized by coating with anti-F antibody bearing the A11 determinant. Agglutinator was prepared by injecting rabbits lacking the A11 determinant with IgG of the same group a and group b allotypes but possessing the A11 determinant. Several sensitizors for detecting the A11 specificity were prepared by immunizing rabbits possessing the A11 determinant with type F rabbit erythrocytes. The determinant was found to be associated with the IgG class of immunoglobulins by filtration and by DEAE chromatography. Studies with enzymatic fragments and subunits of IgG show that the A11 determinant is carried on the heavy (H) chain. Although the determinant was detectable on the (Fab′)2 fragments obtained by pepsin hydrolysis of IgG, the requirement for the integrity of the inter-H chain disulfide bond precluded its detection on isolated H or light (L) chains. The results further suggest that certain structures on both H chains of a given IgG molecule require proper orientation for interaction with the anti-A11 serum. © 1969.