ABSTRACT
AIM: To investigate whether wheat germ agglutinin (WGA) could induce apoptosis in mouse fibroblast cell line L929 and the possible molecular mechanism underlying. METHODS: The cells were exposed to WGA or its succinylated form (sWGA) for 24 h and both attached cells and the cells in supernatant were collected. The percentages of apoptotic cells were estimated by flow cytometry after staining with propidium iodide. Cell morphology was observed under fluorescence microscope after staining the cells with acridine orange. RESULTS: WGA treatment resulted in significant increase of the low DNA content peak (sub-G 1) that representing apoptotic cells, whereas sWGA did not. Morphologic study demonstrated that exposure to WGA induced nuclear fragmentation while sWGA not. CONCLUSION: These results indicate that WGA (specific for both sialic acid and GlcNAc) induces apoptosis in L929 cells, whereas sWGA (specific only for GlcNAc) does not. It is possible that binding to sialic acid residues on the cell surface of L929 is essential for WGA to induce apoptosis. Apoptosis induction may be, at least in part, involved in the cytotoxicity of WGA. [
ABSTRACT
AIM: To study cellular and molecular mechanism involved in increasing susceptibility of infection in psychological stress persons. METHODS: Comparative studies were performed with double staining and flow cytometry analysis on immunophenotyping and in vitro expression of early activating surface molecule CD69 in response to mitogens on T cells from peripheral blood of 20 healthy college student volunteers before and after psychological stress. A series of term final examinations was defined as psychological stress. RESULTS: Immunophenotyping analysis showed no statistically significant difference in the percentage of CD2, CD3, CD4, CD8, CD19, CD20, CD16 and CD56 positive lymphocyte populations before and after psychological stress. There was a statistically significant decrease in the in vitro expression of CD69 in response to polyclonal stimulators on the T cells from persons after psychological stress than those before psychological stress. The percentage of CD69 expression (CD69+CD3+/CD3+%) in response to PHA and PDB in the whole blood culture for 72 hours decreased respectively from 28.1?4.1 and 80.7?6.8 on the T cells obtained before psychological stress to 17.6?3.8 and 65.8?7.9 on those obtained after psychological stress, while there was no statistically significant difference between the CD69 expression rates without stimulators on the T cells obtained before and after psychological stress. CONCLUSIONS: The effects of psychological stress to immune system is not on the level of changing proportions of the sub-populations within peripheral blood lymphocytes. Psychological stress can decrease the activating response of T cells in healthy persons, which may be responsible for the increase of susceptibility to infection in the psychological stress persons.