Biochemical Evidence for Multiple Ia Molecules
Both Ia antigens and Ir genes map to the I-A and I-E subregions of the mouse H-2 gene complex. The I-A subregion codes genes for three polypeptide chains, designated Aα, Aβ, and Eβ while the I-E subregion maps the gene for Eα (1). The map position of a third invariant Ia polypeptide chain designated I is not known. Thus, the I-A molecule and I-E molecule are formed by the non-covalent binding of the three chains, α (34,000 M.W.), β (28,000 M.W.) and I (31,000 M.W.). Recent studies using mutant strains and monoclonal antibodies have clearly shown that Ia antigens are the immune response gene products. The Ia molecules are involved in generating histo-incompatibility, alloreactivity, autoreactivity, as well as generating immune response to a variety of foreign antigens. Studies using alloreactive and antigen-specific T-cell clones have shown that Ia molecules most probably mediate immune activity by presentation of antigens to T-cells (2). Yet, it is not clear how the Ia molecules interact specifically with a variety of antigens under Ir gene control. One possibility is that Ia molecules have several antigenic sites which interact with different antigens. Recent studies have shown that there may be multiple epitopes of similar Ia antigens which are spatially distributed through the Ia molecule (3). Another possibility is that there are multiple Ia molecules, each of which can interact specifically with different antigens. To investigate this question, we have begun the biochemical study of Ia molecules using monoclonal antibodies. In this report, we will present preliminary evidence that there are multiple I-A and I-E molecules (4).
KeywordsPolypeptide Chain Alpha Chain Beta Chain Neuraminic Acid Adherent Cell Population
Unable to display preview. Download preview PDF.
- 4.Lafuse, W. P., Corser, P. S., David, C. S., Immunogenetics, in press.Google Scholar