Disruption of epithelial gamma delta T cell repertoires by mutation of the Syk tyrosine kinase.

Abstract

Chimeric mice in which lymphocytes are deficient in the Syk tyrosine kinase have been created. Compared with Syk-positive controls, mice with Syk -/-lymphocytes display substantial depletion of intraepithelial ya T cells in the skin and gut, with developmental arrest occurring after antigen receptor gene rearrangement. In this dependence on Syk, subsets of intraepithelial y8 T cells are similar to B Immunoblotting. Cells were lysed in 1% Nonidet P-40 lysis buffer with protease and phosphatase inhibitors. Post-nuclear supernatants were immunoprecipitated serially with anti-Syk and anti-Zap-70 antisera, followed by protein A Sepharose CL-4B beads (Pharmacia). After electrophoresis on SDS/9% polyacrylamide gels, proteins were transferred to poly(vinylidene difluoride) membrane (Bio-Rad), blotted with anti-Syk sera (1:100) or anti-Zap-70 sera (1:100), and detected by enhanced chemiluminescence (DuPont). Anti-Syk antiserum was against residues 260-370 (the unique region between the carboxyl-Src homology 2 domain and the kinase domain), and does not recognize

A New Look at Syk in αβ and γδ T Cell Development Using Chimeric Mice with a Low Competitive Hematopoietic Environment

“…Our results are in striking contrast to the severe reduction in Syk Ϫ/Ϫ intestinal ␥␦ T IELs previously reported by Mallick-Wood et al (12). It is important to note that those results were obtained by studying embryo aggregation chimeras.…”

“…A number of reports have investigated the effects of Syk or ZAP-70 deficiency on the development of these ␥␦ T cell subsets, the reduction being likely to relate to abnormal development of precursors during fetal life (6). Allophenic chimeras generated by aggregating Syk Ϫ/Ϫ and recombination-activating gene (RAG) 2 Ϫ/Ϫ morulae confirmed the essential role for Syk in DETC development, but also found a severe reduction in gut IEL ␥␦ T lymphocytes (in contrast to splenic ␥␦ T cells), suggesting that these ␥␦ T cells also rely on Syk (12). Zap70 Ϫ/Ϫ mice also fail to generate intestinal ␥␦ T lymphocytes and develop morphological abnormal DETC, while other ␥␦ T lymphocytes develop relatively normally (13).…”

“…Among HSCs, it may be that a committed progenitor has a selective disadvantage due to the lack of a given gene product and therefore may be competed out by the host progenitors and fail to differentiate further. This may be the case for intraepithelial ␥␦ T cells deriving from Syk Ϫ/Ϫ HSCs which do not develop in Syk Ϫ/Ϫ allophenic chimeras in the RAG2 Ϫ/Ϫ background (12). In a situation where the host progenitors are fewer or are impaired in their own differentiation program, intraepithelial ␥␦ T cells may be generated from Syk Ϫ/Ϫ HSCs.…”

“…We analyzed the development of gut-associated lymphoid cells, a substantial fraction of which derive from an extrathymic pathway Table III aggregation chimeras (12). We hypothesized that competition with host lymphoid precursors might have blocked Syk-deficient IEL development in those experiments and, to test this hypothesis, we compared reconstitution of the intestinal IEL pool in RAG2 and RAG2/␥c mice injected with FL-HSC (Fig.…”

Hypermethylation of the spleen tyrosine kinase promoter in T-lineage acute lymphoblastic leukemia

“…These results suggest that SYK may be involved in propagation of CD3/TCR-independent signals as well (Chu et al, 1999). SYK-deficient mice have no reported ab-T-cell defect, although a subset of gd T cells is impaired in their development (Mallick-Wood et al, 1996).…”