Dendritic epidermal gamma/delta T cells (DETC) activated in vivo proliferate in vitro in response to Mycobacterium leprae antigens

Zeta-chain-associated protein-70 molecule is essential for the proliferation and the final maturation of dendritic epidermal T cells

Adult murine epidermis contains members of the epithelial gammadelta T-cell family called dendritic epidermal T cells (DETCs). Their development and maturation have been the subjects of investigations, but the details are still unclear. T-cell receptor (TCR) zeta-chain-associated protein-70 (ZAP-70), one of the protein tyrosine kinases required for TCR signaling, plays a pivotal role in the development of alphabeta T cells. In mice lacking ZAP-70, thymic development of alphabeta T cells was completely arrested at the immature CD4(+)CD8(+) TCR(low) stage. Here, we examined whether or not the development and maturation of DETCs were altered in ZAP-70-deficient mice. Immunohistochemical analyses of epidermal sheets revealed that the number of DETCs was reduced and their characteristic dendrites were lost or markedly shortened in ZAP-70(-/-) mice. In flow cytometric analyses, the expression levels of gammadelta TCR and Thy-1.2 on the ZAP-70(-/-) DETCs were lower than those on ZAP-70(+/-) DETCs. The expression of a very early activation antigen, CD69, was not detected on ZAP-70(-/-) DETCs, whereas CD69 was expressed on ZAP-70(+/-) DETCs. Furthermore, ZAP-70(-/-) DETCs showed markedly reduced proliferation and no IL-2 gene expression in response to anti-CD3epsilon or concanavalin A stimulation. These results suggest that ZAP-70 is essential for TCR signaling which induces the proliferation and the final maturation of DETCs in the epidermis.

Phenotypic diversity of antigen-presenting cells in ovine-afferent intestinal lymph

The phenotypic and functional repertoire of antigen-presenting cells (APCs) remains incompletely characterized, particularly during the migratory phase of their life history, when these cells leave peripheral tissues and travel via afferent lymphatic vessels to regional lymph nodes. Lymphatic cannulation procedures were used to collect ovine APCs as they migrated from the mucosa of the small intestine to regional lymph nodes. A panel of 19 new monoclonal antibodies (mAbs) was produced to characterize surface molecules expressed on APCs by means of two-color flow cytometry and microscopy. Two broad patterns of mAb reactivity were evident. Twelve mAbs reacted almost exclusively with cells in the APC-gated region, because all these mAbs stained < 3% of cells in the lymphocyte-gated region. Within this group, some mAbs identified distinct subsets of dendritic cells (DCs). The second group of seven mAbs displayed high-intensity staining on cells in the APC-gated region but also reacted with variable numbers (4-26%) of cells in the lymphocyte-gated region. This indicates that molecules recognized by these mAbs are highly expressed on APCs but also occur on other lineages. When new mAbs were analyzed by two-color flow cytometry of cells in afferent intestinal lymph, a wide range of differences in reactivity were observed, especially on CD11b(+), CD11c(+), CD4(+), MHCII(+), and gammasigmaTCR(+) cells. Although molecular specificities of mAbs reported here remain undefined, marked heterogeneity of staining patterns indicates considerable phenotypic, and probably functional, diversity within APC population in afferent intestinal lymph. MAbs reported here will provide useful tools to explore these features further.

Direct effect of croton oil on intestinal epithelial cells and colonic smooth muscle cells

AIM

To investigate the direct effect of croton oil (CO) on human intestinal epithelial cell (HIEC) and guinea pig colonic smooth muscle cells in vitro.

METHODS

Growth curves of HIEC were drawn by MTT colorimetry. The dynamics of cell proliferation was analyzed with flow cytometry, and morphological changes were observed under light and electron microscopy after long-term (6 weeks) treatment with CO. Expression of cyclooxygenase-2 (COX-2) mRNA was detected by dot blot in HIEC treated with CO. Genes related to CO were screened by DD-PCR, and the direct effect of CO on the contractility of isolated guinea pig colonic smooth muscle cells was observed.

RESULTS

High concentration (20-40 mg x L(-1)) CO inhibited cell growth significantly (1, 3, 5, 7d OD sequence: (20 mg x L(-1)) 0.040+/-0.003, 0.081+/-0.012, 0.147+/-0.022,0.024+/-0.016; (40 mg x L(-1)) 0.033+/-0.044, 0.056+/-0.012, 0.104+/-0.010, 0.189+/-0.006; OD control 0.031+/-0.008, 0.096+/-0.012, 0.173+/-0.009, 0.300+/-0.016, P<0.01), which appeared to be related directly to the dosage. Compared with the control, the fraction number of cells in G1 phase decreased from 0.60 to 0.58, while that in S phase increased from 0.30 to 0.34 and DNA index also increased after 6 weeks of treatment with CO (the dosage was increased gradually from 4 to 40 mg x L(-1)). Light microscopic observation revealed that cells had karyomegaly, less plasma and karyoplasm lopsidedness. Electron microscopy also showed an increase in cell proliferation and in the quantity of abnormal nuclei with pathologic mitosis. Expression of COX-2 mRNA decreased significantly in HIEC treated with CO. Thirteen differential cDNA fragments were cloned from HIEC treated with CO, one of which was 100 percent homologous with human mitochondrial cytochrome C oxidase subunit II. The length of isolated guinea pig colonic smooth muscle cells was significantly shortened after treatment with CO (P<0.05).

CONCLUSION

At a high CO concentration (>20 mg x L(-1)), cell growth and proliferation are inhibited in a dosage-dependent manner. Increase in cell proliferation and in malignant conversion of the cellular phenotype is observed in cells cultured chronically with CO. COX-2 mRNA expression decreases significantly, while human mitochondrial cytochrome C oxidase subunit IImRNA expression increases significantly in HIEC treated with CO. CO also has a direct effect on the contractility of Guinea pig colonic smooth muscle cells.