Erik Thorsby

Typing of DNA from 94 unrelated children with celiac disease (CD) with HLA-DQA1 and -DQB1 allele-specific oligonucleotide probes revealed that all but one (i.e., 98.9%) may share a particular combination of a DQA1 and a DQB1 gene. These genes are arranged in cis position on the DR3DQw2 haplotype and in trans position in DR5DQw7/DR7DQw2 heterozygous individuals. Thus, most CD patients may share the same cis- or trans-encoded HLA-DQ alpha/beta heterodimer.

Celiac disease (CD) is most probably an immunological disease, precipitated in susceptible individuals by ingestion of wheat gliadin and related proteins from other cereals. The disease shows a strong human HLA association predominantly to the cis or trans encoded HLA-DQ(alpha 1*0501,beta 1*0201) (DQ2) heterodimer. T cell recognition of gliadin presented by this DQ heterodimer may thus be of immunopathogenic importance in CD. We therefore challenged small intestinal biopsies from adult CD patients on a gluten-free diet in vitro with gluten (containing both gliadin and other wheat proteins), and isolated activated CD25+ T cells. Polyclonal T cell lines and a panel of T cell clones recognizing gluten were established. They recognized the gliadin moiety of gluten, but not proteins from other cereals. Inhibition studies with anti-HLA antibodies demonstrated predominant antigen presentation by HLA-DQ molecules. The main antigen-presenting molecule was established to be the CD-associated DQ(alpha 1*0501, beta 1*0201) heterodimer. The gluten-reactive T cell clones were CD4+, CD8-, and carried diverse combinations of T cell receptor (TCR) V alpha and V beta chains. The findings suggest preferential mucosal presentation of gluten-derived peptides by HLA-DQ(alpha 1*0501, beta 1*0201) in CD, which may explain the HLA association.

This paper describes a new cell isolation and HLA typing technique, which permits cell separation and HLA class I or class II typing to be performed in 70 min. Magnetic monodisperse microspheres (Dynabeads TM) were coated with monoclonal antibodies (MAbs) specific for the CD8 T cell antigen or for HLA class II monomorphic epitopes. They could then be used to obtain HLA class I or class II positive cells directly from ACD blood in approximately 15 min by the use of magnetic separation. The cells (attached to the microspheres) were subsequently used in microcytotoxic HLA typing (total incubation time of 55 min) using acridin orange/ethidiumbromide to stain viable (yellow) and dead (red) cells. It was found that this immunomagnetic (IM) HLA typing technique was specific, has a sensitivity superior to that observed for conventional microcytotoxicity assays and gave low background staining. IM HLA-ABC typing of 50 healthy donors and 10 patients and IM HLA-DR typing of 25 healthy donors and 30 patients gave results corresponding well with that obtained independently by conventional HLA typing (concordancy rates 92-100%). Furthermore, the IM HLA typing technique permitted reliable HLA class II typing of blood cells from six patients where conventional HLA class II typing was impossible. The IM HLA typing technique also enables HLA class I and II typing to be quickly and reliably performed on cells from ACD blood of cadaveric donors.