Site-specific antibodies distinguish single amino acid substitutions in position 57 in HLA-DQ β-chain alleles associated with insulin-dependent diabetes
Summary, in English
The HLA-DQ β-chain gene shows a close association with susceptibility or resistance to autoimmune insulin-dependent diabetes mellitus (IDDM) and it has been suggested that the amino acid in position 57 may be of pathogenetic importance. To study the expression of the IDDM associated HLA-DQ β-chain alleles, we immunized rabbits with 12 to 13 amino acid long peptides representing HLA-DQw7 and -DQw8 allelic sequences, differing only by one amino acid in position 57 being aspartic acid (Asp) and alanine (Ala), respectively. Immunoblot analysis of lymphoblastoid cells showed that several antisera recognized a 29-kDa protein, equivalent to the expected molecular size of the HLA-DQ β-chain to yield two antisera for HLA-DQw7 (pos. 57(Asp)) and three antisera for HLA-DQw8 (pos. 57(Ala)) positive cells. Analysis of HLA-DR 3/4 positive IDDM patients (n = 24) and controls (n = 19) showed that all (100%) patients were positive for pos. 57(Ala) antiserum compared to 13 of 19 (68%) of the controls. The remaining six controls reacted with the pos. 57(Asp) antisera, whereas none of the patients did. We have therefore successfully been able to generate site-specific antibodies that distinguish single amino acid substitutions in predetermined positions of allelic HLA-DQ β-chain gene products. Such sera should become useful to detect and investigate HLA associated susceptibility to autoimmune diseases in man.
Journal of Immunology
American Association of Immunologists
- Endocrinology and Diabetes
- Medical Genetics
- ISSN: 0022-1767