Anti-CD3D (aa 22-100) polyclonal antibody

T cells recognize antigens via their cell surface TCR and are classified as either alpha beta or gamma delta depending on the variable chains in their TCR, alpha and beta or gamma and delta, respectively. Both alpha beta and gamma delta TCRs also contain several invariant chains, including CD3 delta, which support surface TCR expression and transduce the TCR signal. Mutations in variable chains would be expected to affect a single T cell lineage, while mutations in the invariant chains would affect all T cells. Consistent with this, all CD3 delta-deficient patients described to date showed a complete block in T cell development. However, CD3 delta-KO mice have an alpha beta T cell-specific defect. Here, we report 2 unrelated cases of SCID with a selective block in alpha beta but not in gamma delta T cell development, associated with a new splicing mutation in the CD3D gene. The patients' T cells showed reduced CD3D transcripts, CD3 delta proteins, surface TCR, and early TCR signaling. Their lymph nodes showed severe T cell depletion, recent thymus emigrants in peripheral blood were strongly decreased, and the scant alpha beta T cells were oligoclonal. T cell-dependent B cell functions were also impaired, despite the presence of normal B cell numbers. Strikingly, despite the specific loss of alpha beta T cells, surface TCR expression was more reduced in gamma delta than in alpha beta T cells. Analysis of individuals with this CD3D mutation thus demonstrates the contrasting CD3 delta requirements for alpha beta versus gamma delta T cell development and TCR expression in humans and highlights the diagnostic and clinical relevance of studying both TCR isotypes when a T cell defect is suspected.

NC/Nga (NC) is a newly discovered model mouse for human atopic dermatitis, NC mice showing specific symptoms such as dermatitis and overproduction of IgE. To detect the loci responsible for the onset of dermatitis in the mice, backcross (N2) progeny between (NCxMSM/MS)F1 and NC were generated, where MSM/MS is an inbred strain from Japanese wild mice, Mus musculus molossinus. Linkage disequilibrium between dermatitis and various chromosome-specific microsatellite markers was then examined in the N2 segregants with severe dermatitis. The analysis revealed that the locus of the major determinant (designated here as derm1) was tightly linked to D9Mit163, D9Mit72, D9Mit143, D9Mit103, D9Mit207, and D9Mit209, because these markers showed the highest and most significant chi (2) values. Since no recombination was observed among the markers in our linkage map, a radiation hybrid (RH) panel was applied to locate the derm1 locus more precisely. The markers were separated on the RH map, and their order was D9Mit163-D9Mit72-D9Mit143D9Mit103-D9Mit207-D9Mit209 from the centromere. Several functional candidate genes are located near the locus derm1. These candidates are Thy1, Cd3d, Cd3e, Cd3g, Il10ra, Il18, and Csk, all of which could be involved in allergic responses through effects on T-cell function. Of these candidates, Csk is the strongest for NC dermatitis, since its map position was most tightly linked to the derm1 locus.