1 Department of Oral Biochemistry, Division of Oral Structure, Function and Development, Asahi University School of Dentistry, 1851-1 Hozumi, Mizuho, Gifu, 501-0296, Japan
2 Chemistry Laboratory, Department of Business Administration, Asahi University School of Business Administration, 1851-1 Hozumi, Mizuho, Gifu 501-0296, Japan
3 Department of Anesthesiology, Division of Oral Pathogenesis and Disease Control, Asahi University School of Dentistry, 1851-1 Hozumi, Mizuho, Gifu, 501-0296, Japan
4 Department of Oral and Maxillofacial Surgery, Division of Oral Pathogenesis and Disease Control, Asahi University School of Dentistry, 1851-1 Hozumi, Mizuho, Gifu, 501-0296, Japan
We have already reported that mouse Oral Squamous Carcinoma Cells (OSCCs) Sq-1979 specifically enhance the immunosuppressive activity of mesenchymal 10T1/2 cells via the functional soluble factor (s).
In this report, we attempted to identify soluble factor(s) mediating the immunosuppression of Sq-1979 cells.
L5-11 cells are a variant established from the metastatic lymph nodes of Sq-1979-implanted mice. Unlike parental Sq-1979 cells, however, L5-11 cells lack promotion of immunosuppressive activity in 10T1/2 cells. In order to identify cytokine mRNAs specifically expressed in Sq-1979 cells but not in L5-11 cells, cDNA microarray was performed. Conditioned medium from Sq-1979 cells (CM) was absorbed by several different neutralizing antibodies (abs) against the corresponding cytokines. The absorbed CM was then co-cultured with 10T1/2 cells and anti-CD3 antibody-stimulated mouse spleen cells. The Interferon (IFN) -γ producing capability of the stimulated spleen cells was evaluated using Enzyme-Linked Immunosorbent Assay (ELISA). By using a specific cytokine product instead of CM in this co-culture system the source of the immunosuppressive effect was identified.
The expression of Ccl2, Ccl7, Il1-α, IL1f6 and Il6 mRNAs was specifically elevated in Sq-1979 cells compared to L5-11 cells. The suppression of the IFN-γ producing capability of stimulated spleen cells in the co-culture system was specifically alleviated by absorbing the CM with anti-IL-1α ab. We further demonstrated that the immunosuppressive effect of CM in the co-culture system could be completely substituted by IL-1α protein (50 pmol/ ml).
The immunosuppressive function of 10T1/2 cells is specifically promoted by IL-1α, secreted by Sq-1979 cells.
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