Japanese Journal of Oral Biology

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Fluorescence polarization measurement was applied to detect the impaired Con A-induced mitogenic responses in tumor-bearing mice. Spleen lymphocytes from normal C₃H/HeN mice and from those inoculated 1×106 Ehrlich ascites tumor cells were treated with Con A and examined for their fluorescence polarization changes (P-value) using fluorescein diacetate and a polarization spectrofluorometer. Murine spleen cells when stimulated by 5μg/ml of Con A at 37°C for 45 min showed a high polarization change with a reduction rate of p-value, 0.79±0.03 (n=33). This Con A-induced polarization change of spleen cells was almost completely inhibited by α-methylmannoside, a competitive inhibitor of Con A-binding to the cell surface. Spleen lymphocytes from tumor-bearing mice showed much less polarization changes with a reduction rate of P-value, 0.91±0.04 (n=33). This low fluorescence polarization change appeared as early as 3 days after tumor inoculation. Impairement of mitogenic responses as revealed by ³H-thymidine uptake in tumor-bearing mice also appeared 3 days after tumor inoculation. These results indicate that the fluorescence polarization measurement may be a valuable tools for the detection of impaired mitogenic responses of lymphocytes in tumor-bearing mice.

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Spleen lymphocytes of normal CaH/HeN mouse were incubated with the serum or cell-free ascites of Ehrlich tumor-bearing mice. These cells were stimulated with 5μg/ml of Con A and then examined for their mitogenic responses by fluorescence polarization changes and ³H-thymidine uptake. Fluorescence polarization changes of spleen cells treated with either tumor ascites or serum were markedly suppressed, as was the 8H-thymidine uptake. Human peripheral blood lymphocytes from a healthy donor were also incubated with the serum from 14 healthy men and 15 cancer patients and then examined for their Con A-induced fluorescence polarization changes. Reduction in mitogenic responses of normal lymphocytes treated with cancer serum was easily detected by this fluorescence polarization measurement. This suppressive effect of test sera on Con A-induced fluorescence polarization changes was correlated with the amount of a immunosuppressive acidic protein, IAP in test sera. These results indicate that the fluorescence polarization test can be used for the detection of an immunosuppressive factor (s), which induces the impairement of mitogenic response of lymphocytes, in the sera of cancer patients and tumor-bearing mice.

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