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Biomedical subjects

M E Kemp

Publications and source records attributed to M E Kemp.

3 recordsLinked to original sources

The major histocompatibility complex and autoimmunity.

Study of two diseases with autoimmune characteristics (IDDM and SLE) has demonstrated that alleles carried in the MHC can confer disease susceptibility. The MHC alleles most strongly associated with the development of IDDM are encoded within the class II region (HLA-DR or -DQ). Recent studies indicating that the class III gene products TNF alpha and beta may play a critical role in the initiation of the autoimmune attack on the pancreatic beta-cells have suggested the possibility that the class III region may also contribute to genetic susceptibility in IDDM. In SLE, although there is some evidence suggesting that certain alleles of class II genes may confer disease risk, a more striking association has been detected in the class III region. Deficiency of the class III encoded C4A molecule (either homozygously or heterozygously) shows a high correlation with disease risk. This finding is attractive because C4A plays a central role in the metabolism of immune complexes, the aberrant deposition of which leads to the most prominent alterations in SLE.

Animals

Deletion of C4A genes in patients with systemic lupus erythematosus.

To define the relationship between inheritance of major histocompatibility complex (MHC) alleles and susceptibility to the development of systemic lupus erythematosus (SLE), we examined the MHC class I, II, and III phenotypes of white SLE patients and characterized the structures of their class III MHC genes, using Southern blotting. Nine of 88 SLE patients (10.2%) were C4A null. As detected by Southern blot analysis, the C4A gene was deleted from both chromosomes in 8 of the 9 C4A-null patients. Deletions affecting only 1 chromosome (heterozygous) were detected in the remaining C4A-null patient and in 34.5% of SLE patients who were not C4A deficient (compared with 12.5% of controls; P less than 0.05). These results indicate that deletion of the C4A gene is a common genetic marker for SLE. Deletions of C4A were observed most commonly as part of the HLA-B8;DR3 extended haplotype, although deletions were also detected in different HLA haplotypes. Because of the critical role of C4A in the processing of immune complexes, deficiency of C4A may, itself, confer susceptibility to the development of SLE.

Alleles