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Limiting dilution analysis of alloantigen-reactive T lymphocytes. II. Effect of cortisone and cyclophosphamide on cytolytic T lymphocyte precursor frequencies in the thymus
Journal Article --- Old month value: Sep
A minimal estimate of the frequency of cytolytic T lymphocyte precursors (CTL-P) in the thymus was determined by application of Poisson statistics to limiting dilution analysis. A mean CTL-P frequency of 1/1467 was obtained for C57BL/6 (H-2b) thymus cells activated by DBA/2 (H-2d) irradiated spleen cells and assayed against P-815 mastocytoma (H-2d) target cells. CTL-P frequencies were also obtained for spleen, nylon wool column purified spleen, peripheral blood, and lymph node cell populations. The effect of in vivo drug treatments on CTL-P frequencies was then examined. Cortisone at 100 mg/kg dramatically increased the CTL-P frequency in thymus by more than 20-fold despite a drastic reduction in the number of total thymus cells. The same cortisone treatment did not affect the CTL-P frequency in spleen. In contrast, cyclophosphamide at 300 mg/kg decreased the CTL-P frequency in spleen by more than 10-fold without affecting that in thymus. Cyclophosphamide at 100 mg/kg did not produce any significant change. A detailed explanation of the calculation of CTL-P frequencies is provided and their validity is discussed.
Animals Cyclophosphamide/*pharmacology Cytotoxicity, Immunologic Hydrocortisone/*pharmacology Immunologic Techniques *Isoantigens Lymphocyte Culture Test, Mixed Mice Mice, Inbred C57BL Mice, Inbred DBA Spleen/immunology T-Lymphocytes/*immunology Thymus Gland/immunology
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