Topographical relationships among H-2 specificities controlled by theD region

In the present work, we used the differential redistribution method to study the molecular expression of several H-2 specificities controlled by theD region of theH-2 ^a haplotype. We observed that: capping of the private specificity H-2.4 induced capping of the public specificities H-2.3, H-2.35, and H-2.36, and vice versa; capping of any one of these specificities did not induce capping of the public specificity H-2.28, controlled by the same region. By contrast, capping of the H-2.28 specificity induced capping of these specificities; redistribution of H-2K and H-2D private specificities or redistribution of H-2D private specificity and Ia specificities did not induce capping of the H-2.28 specificity. These data indicate that a part of a molecule carrying the H-2.28 specificity is linked to a molecule carrying H-2.4, H-2.3, H-2.35, and H-2.36 specificities and that a part of a polypeptide chain bearing the H-2.28 specificity is independent from that bearing other specificities controlled either by theD region (i.e., H-2.4, H-2.3, H-2.35, and H-2.36) or by theK andI regions. These results further strengthened the hypothesis of the existence of at least two genes controlling theD-region H-2 antigenic specificities.