BACKGROUND/AIMS: The expression of CD40 in gastric cancer has not been studied. The aims of this study were to determine the expression of CD40 in gastric cancer and to investigate the effect of CD40 on the apoptosis of gastric cancer cells. METHODS: We examined the expression of CD40 by immunohistochemistry and flow cytometry. CD40 mRNA in 5 gastric cancer cell lines was analyzed by RT-PCR. To assess the effect of CD40 on the viability of gastric cancer cells, we performed MTT assay. The effect of CD40 signaling on the apoptosis of gastric cancer cells was examined by annexin V affinity assay. RESULTS: Twelve of twenty human gastric cancer tissues demonstrated positive staining for CD40. Among 5 gastric cancer cell lines, AGS cell line expressed membrane-bound CD40 antigen and CD40 mRNA. In AGS cells, CD40 stimulation significantly reduced the cell viability. CD40 ligation significantly increased the apoptosis in AGS cells compared to the control. CONCLUSIONS: CD40 is expressed in human gastric cancer tissues and gastric cancer cell line, and induces apoptosis in gastric cancer cells. These results suggest that CD40 expression in gastric cancer may play an important role in host defense mechanism against the gastric cancer.
Antigens, CD40/*analysis/physiology ; *Apoptosis ; Cell Line, Tumor ; Humans ; Immunohistochemistry ; Stomach Neoplasms/*chemistry/pathology

OBJECTIVETo explore the specific cytotoxic T lymphocyte (CTL) induced by dendritic cells (DC), which were transfected by the plasmid pC53-SN3 encoding p53 gene.

METHODSDC derived from HLA-A2(+) mononuclear cells of the 24-lung cancer patients was transfected with the plasmid pC53-SN3 by lipofectamine and then co-cultured with auto-unpurified T cells to induce potent CTL (T-pC53-SN3). The cytolysis of specific CTL against Calu-6, a HLA-A2(+) human lung cancer cell line, was measured by using lactate dehydrogenase (LDH) releasing assay.

RESULTSThe expression of CD(1a) and CD(83), the correlative markers of DC, increased apparently after transfected with plasmid pC53-SN3, the expression rate was (5.45 +/- 0.89)% and (3.26 +/- 0.47)% versus (52.15 +/- 11.56)% and (25.78 +/- 12.35)%. CD(14) decreased apparently, but other DC correlative markers of CD(1a), CD(40), CD(86), and HLA-DR remained almost the same as that before transfection. Compared with T-IL-2, the CTL derived from PBMNC stimulated by IL-2 (100 U/ml), the cytolytic activity of T-pC53-SN3 against Calu-6 cell line showed a significant increase, but cytolytic activity was 56.79 +/- 15.67 and 39.33 +/- 9.88, respectively, when effect cells: target cells was 10:1. The expression of the CD(8), CD(69), and CD(45)RO/CD(8) of T-pC53-SN3 cells increased significantly, but that of CD(3), CD(4), CD(86), ect, was not significantly different from those of T-pCMV-neo.

CONCLUSIONSIt showed that DC transfected by p53 gene could induce potent HLA-A(2) restrictive CTL to kill tumor cell efficiently.

Antigens, CD ; analysis ; B7-2 Antigen ; CD40 Antigens ; analysis ; Cell Line, Tumor ; immunology ; Coculture Techniques ; Cytotoxicity, Immunologic ; immunology ; Dendritic Cells ; drug effects ; immunology ; metabolism ; Granulocyte-Macrophage Colony-Stimulating Factor ; pharmacology ; Humans ; Interleukin-4 ; pharmacology ; Membrane Glycoproteins ; analysis ; T-Lymphocytes ; immunology ; Tumor Suppressor Protein p53 ; genetics ; physiology

Mycophenolate mofetil (MMF) is a newly developed immunosuppressor, widely used in allogeneic bone marrow transplant. The purpose of this study was to evaluate the effects of mycophenolic acid (MPA), the active metabolite of MMF in vivo, on the maturation and immunologic function of murine bone marrow-derived dendritic cells (DC), and to explore the underlying mechanisms of MMF in graft versus host disease. Cultured DC were treated with MPA at doses of 0.01 and 0.1 micro mol/L. The immunophenotype of DC in control and treated groups was analyzed by flow cytometry. The capability of antigen presentation and the stimulatory activity of the DC on allogeneic T cells were tested by incorporation of (3)H-TdR and mixed lymphocyte reaction respectively. IL-12 production in culture supernatant and the levels of Th1/Th2 cytokines such as IL-2, IFN-gamma, IL-4 and IL-10 in mixed lymphocyte reaction (MLR) supernatant were examined by ELISA assay. The results showed that DCs cultured in the presence of MPA expressed low levels of CD40, CD80 and CD86, and exhibited weak activity in stimulating the proliferation of allogeneic T cells and antigen presenting function with a concurrent reduction of IL-12 production. Allogeneic T cells stimulated by MPA-treated DC expressed higher levels of Th2 cytokines such as IL-4 and IL-10 but lower levels of Th1 cytokines such as IL-2 and IFN-gamma than those stimulated by DC without MPA treatment. It is concluded that MPA, and hence MMF, exerts a negative effect on the maturation and immunologic functions of DC in culture, and drives a shift of Th1 to Th2 cytokines in MLR.
Animals ; Bone Marrow Cells ; drug effects ; physiology ; CD40 Antigens ; analysis ; Dendritic Cells ; drug effects ; immunology ; physiology ; Female ; Graft vs Host Disease ; prevention & control ; Immunosuppressive Agents ; pharmacology ; Interleukin-12 ; secretion ; Lymphocyte Activation ; drug effects ; Male ; Mice ; Mice, Inbred BALB C ; Mice, Inbred C57BL ; Mycophenolic Acid ; pharmacology