Gerald T. Nepom

Structural and functional constraints on HLA class II dimers implicated in susceptibility to insulin dependent diabetes mellitus

Destruction of insulin secreting 13 cells in the islets of Langerhans in the pancreas is an immune mediated process in insulin dependent diabetes mellitus (IDDM). Continued [3 cell destruction eventually leads to insulin dependence and clinical presentation (Eisenbarth, 1986). Although the disease is likely to be polygenic, the major histocompatibility complex (MHC) locus on chromosome 6 is the primary genetic determinant of IDDM susceptibility. In earlier studies, positive associations of IDDM were noted with the HLA-DR1, DR3, DR4 and DRw6 specificities, while the DR2 specificity is negatively associated with IDDM (Bertrams and Baur, 1984; Cudworth and Wolf, 1984; Thomson et al, 1988). More recent studies have indicated that some of these associations of IDDM with DR alleles can be explained by linkage disequilibrium between HLA-DR and nearby HLA-DQ alleles. Greater than 95% of DR4 IDDM patients have the DQ3.2 allele (DQBI*0302(DQw8)), while DR4, DQ3.1 (DRBI*0301(DQw7)) individuals are not susceptible to the disease. Thus the DQBI*0302 allele and not the linked DR allele accounts for the association of HLA-DR4 with IDDM, and is the most likely known candidate susceptibility gene (Kim et al, 1985; B. S. Nepom et al, 1986; G. T. Nepom et al, 1986; Schreuder et al, 1986; Michelsen and Lernmark, 1987; Monos et al, 1987; Owerbach et al, 1989; Robinson et al, 1989). It is similarly possible, but not yet demonstrated, that the positive association of IDDM with DR1, DR3 and DR6 and the negative association with DR2 can be attributed to the linked DQ genes DQBI*0501(DQw5), DQBI*0201(DQw2), DQBI*0604(DQw6) and DQBI*0502(DQw5) respectively. Comparisons of nucleotide sequences of these DQ alleles have led to the hypothesis that a single amino acid residue at codon 57 of the DQB1 alleles is of primary importance in predisposition to the disease (Todd et al, 1987; Horn et al, 1988; Morel et al, 1988). This hypothesis states that a small, non-charged amino acid at codon 57 of the DQB1 gene is permissive for disease development, while a charged amino acid at codon 57 of the DQB1 chain offers protection from disease. However, numerous

Enhanced detection of immunoglobulin binding by a modified ELISA

A modification of the ELISA assay is described which significantly enhances the chromogenic signal, thereby increasing the sensitivity of the assay. This enhanced ELISA employs a protein A-HRP conjugate to detect antibody bound to antigen coated polystyrene plates, followed by incubation with an anti-protein A-HRP conjugate as the amplification step. This enhanced ELISA is rapid, inexpensive, uses commercially available reagents and maintains the low background and high specificity of standard ELISA.

DR5 (DRw11, DRw12): 2-D Gel Patterns

HLA-DR5 was subdivided after the 9th Workshop into two specificities, HLA-DRw11 and HLA-DRwl2 (1). Despite some discussion in the 10th Workshop (2), it was finally agreed to retain both DRw11 and DRw12 as splits of DR5(3). The biochemical characteristics of the class II molecules expressed by the DRwll and DRwl2 cell lines are described in this report.

2. Durable Efficacy of Alefacept in New-Onset Type 1 Diabetes: Evidence for Lasting Modulation of Effector and Regulatory T Cells (231-OR)

SamenvattingType 1 diabetes (T1D) results from destruction of pancreatic beta cells by autoreactive effector T cells. We hypothesized that a combination of targeted depletion and modulation of effector T cell activity by alefacept would result in prolonged preservation of endogenous insulin secretion in patients with newly diagnosed T1D. In a multicenter, randomized, double-blind, placebo-controlled trial we compared alefacept (two 12-week courses of 15 mg intramuscularly per week, separated by a 12-week pause) with placebo in patients with new-onset T1D. Endpoints assessed at 24 months included meal-stimulated C-peptide area under the curve (AUC), insulin use, hypoglycemic events, and immunologic responses.

DQw3 (DQw7, DQw8, DQw9): 2-D Gel Patterns

DQw3 polymorphism has been described previously at the serologic, biochemical, and genomic level (1–8). In the present study, HLA class II α and β chain polymorphism was investigated by two-dimensional (2-D) gel electrophoresis of immunoprecipitated molecules in a panel of 27 HLA-DQw3 lymphoblastoid cell lines (Table 1).