The majority of T lymphocytes carrying the NK cell marker NK1.1 (NKT cells) depend on the CD1d molecule for their development and are distinguished by their potent capacity to rapidly secrete cytokines upon activation. A substantial fraction of NKT cells express a restricted TCR repertiore using an invariant TCR Vα14-Jα281 rearrangement and a limited set of TCR Vβ segments, implying recognition of a limited set of CD1d-associated ligands. A second group of CD1d-reactive T cells use diverse TCR potentially recognizing a larger diversity of ligands presented on CD1d. In TCR-transgenic mice carrying rearranged TCR genes from a CD1d-reactive T cell with the diverse type receptor (using Vα3.2/Vβ9 rearrangements), the majority of T cells expressing the transgenic TCR had the typical phenotype of NKT cells. They expressed NK1.1, CD122, intermediate TCR levels, and markers indicating previous activation and were CD4/CD8 double negative or CD4+. Upon activation in vitro, the cells secreted large amounts of IL-4 and IFN-γ, a characteristic of NKT cells. In mice lacking CD1d, TCR-transgenic cells with the NKT phenotype were absent. This demonstrates that a CD1d-reactive TCR of the “non-Vα 14” diverse type can, in a ligand-dependent way, direct development of NK1.1+ T cells expressing expected functional and cell-surface phenotype characteristics.

A specialized subpopulation of T lymphocytes is reactive to the MHC class I‐like molecule CD1d. It is not clear which cells are the major antigen‐presenting cells in vivo in the activation of CD1‐restricted immune responses. We have characterized a subset of B lymphocytes expressing six‐ to eightfold higher levels of CD1 than the bulk of B cells. The cells have a surface phenotype (CD21high, CD23low, IgMhigh, IgDlow) found previously to characterize B cells residing in the splenic marginal zones. CD1high B cells localize preferentially to the spleen, and appear late in ontogeny, at 3 – 4 weeks of age. The CD1high B cells were present in mice lacking conventional helper T cells, ruling out an exclusive origin from T cell‐dependent immune responses. Still, some CD1high B cells had been involved in T cell‐dependent immune responses as suggested by mutations in their rearranged immunoglobulin gene regions. The population could still be found in mice with severely reduced B cell reactivity to bacterial lipopplysaccharides (C3H / HeJ mice) and in mice unable to respond to thymus‐independent type 2 antigens (NFR.Xid mice), as well as in germ‐free mice, indicating that bacterial antigens are not major stimuli for the induction of CD1high B cells. In contrast, the CD1high B cell population was severely reduced in CD19‐deficient mice. Taken together, the results imply that the CD1high population is heterogenous and of mixed origin, dependent for its development or maintenance on signaling through the CD19 molecule.

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A specialized subpopulation of T lymphocytes is reactive to the MHC class I-like molecule CD1d. It is not clear which cells are the major antigen-presenting cells in vivo in the activation of CD1-restricted immune responses. We have characterized a subset of B lymphocytes expressing six- to eightfold higher levels of CD1 than the bulk of B cells. The cells have a surface phenotype (CD21(high), CD23(low), IgM(high), IgD(low)) found previously to characterize B cells residing in the splenic marginal zones. CD1(high) B cells localize preferentially to the spleen, and appear late in ontogeny, at 3 - 4 weeks of age. The CD1(high) B cells were present in mice lacking conventional helper T cells, ruling out an exclusive origin from T cell-dependent immune responses. Still, some CD1(high) B cells had been involved in T cell-dependent immune responses as suggested by mutations in their rearranged immunoglobulin gene regions. The population could still be found in mice with severely reduced B cell reactivity to bacterial lipopplysaccharides (C3H / HeJ mice) and in mice unable to respond to thymus-independent type 2 antigens (NFR.Xid mice), as well as in germ-free mice, indicating that bacterial antigens are not major stimuli for the induction of CD1(high) B cells. In contrast, the CD1(high) B cell population was severely reduced in CD19-deficient mice. Taken together, the results imply that the CD1(high) population is heterogenous and of mixed origin, dependent for its development or maintenance on signaling through the CD19 molecule.

We performed molecular genetic analyses of the family of a boy suffering from chronic granulomatous disease (CGD) after immunocytochemically confirming him and his mother to be an X-linked CGD patient and a mosaic carrier, respectively. Southern blot hybridization using cDNA for the cytochrome b 558 heavy chain gene (CYBB) as a probe showed that the patient had a deletion in the 5′ region of the CYBB and his phenotypically normal mother was heterozygous for this deletion. Polymerase chain reaction analyses of all 13 exons of the patient's CYBB gene demonstrated that the deletion extends from exon 7 or neighboring introns to 5′ upstream. The length of the deletion was determined by pulsed-field gel electrophoresis and Southern blotting of genomic DNA using CYBB cDNA and the genetic marker pERT55-5, centromeric to CYBB, as probes. Both probes recognized common SfiI-NotI fragments of 120 kb and 95 kb in normal individuals and the patient, respectively. These results revealed that the patient has a 25-kb deletion spanning from the middle of CYBB to 5′ upstream. This is the only report of a large 5′ deletion in CYBB and also the first observation that CYBB and pERT55-5 are within 120 kb in Xp21.