Invariant chain-independent function of H-2M in the formation of endogenous peptide-major histocompatibility complex class II complexes in vivo.

Efficient loading of major histocompatibility complex class II molecules with peptides requires the invariant chain (Ii) and the class II-like molecule H-2M. Recent in vitro biochemical studies suggest that H2-M may function as a chaperone to rescue empty class II dimers. To test this hypothesis in vivo, we generated mice lacking both Ii and H-2M (Ii-/-M-/-).

Deficient positive selection of CD4 T cells in mice displaying altered repertoires of MHC class II-bound self-peptides.

The role of self-peptides in positive selection of CD4+ T cells has been controversial. We show that some self-peptides are presented by the MHC class II molecule I-A(b) in mice lacking Ii or H-2M but not in mice expressing a transgene-encoded peptide fused to I-A(b). In experiments using specific antibodies to block selection, these low-abundance self-peptides were implicated in the positive selection of some CD4+ T cells in H-2M-/- mice.

HLA class II is associated with the frequency of glutamic acid decarboxylase M(r) 65,000 autoantibodies in Japanese patients with insulin-dependent diabetes mellitus.

Autoantibodies to glutamic acid decarboxylase (GAD65Ab) are common in both caucasian and Japanese patients with insulin-dependent diabetes mellitus (type 1), while the type 1-associated HLA haplotypes differ. In the present study, we analyzed GAD65Ab in relation to HLA-DQ and -DR alleles in Japanese type 1 patients. GAD65Ab were found in 58% short-duration (less than 5 years) type 1, 23% long-duration type 1, 56% slowly progressive type 1, 3% type 2 patients, and 1.

A novel radioligand binding assay to determine diagnostic accuracy of isoform-specific glutamic acid decarboxylase antibodies in childhood IDDM.

Insulin-dependent diabetes mellitus (IDDM) is associated with autoreactivity against GAD but the diagnostic sensitivity (positivity in disease) and specificity (negativity in health) of isoform-specific GAD antibodies have yet to be defined in assay systems suitable for screening large number of samples. One set of IDDM patient (n = 10) and control (n = 50) standard sera were used to develop quantitative antibody assays with in vitro synthesized recombinant 35S-methionine-labelled GAD65 and GAD67, respectively, and protein A-Sepharose to separate free from antibody-bound ligand. Binding levels were not normally distributed (p < 0.

Radioimmunoassay detects the frequent occurrence of autoantibodies to the Mr 65,000 isoform of glutamic acid decarboxylase in Japanese insulin-dependent diabetes.

Glutamic acid decarboxylase antibodies (GAD65Ab) are common in new onset Caucasian insulin-dependent diabetic (IDDM) patients but it is unclear if this marker is also prevalent in patients of other ethnic backgrounds. We determined antibodies against human recombinant GAD in Japanese diabetic patients using a radioimmunoassay with competition between in vitro translated 35S-GAD65 and non-labelled recombinant human GAD65 (rhGAD65). GAD67 antibodies (GAD67Ab) were similarly analyzed but without antigen competition.