Triamcinolone acetonide-3H (TA-3H) binding to subcellular macromolecular fractions was studied in three human lymphoid cell lines (HRIK, RPMI 8226, and MOLT-4), in four lymphosarcomatous tumors, and in leukemic leukocytes obtained from the peripheral blood of three patients with acute lymphocytic leukemia, six with acute myelocytic leukemia, eight with chronic lymphocytic leukemia, and two with chronic myelocytic leukemia. Specific binding, which was manifested by a high binding affinity of TA-3H to the macromolecular fractions and by a greater inhibition of this binding by cortisol, compared with that of inactive steroid epicortisol, was found in the lymphoid cell lines, lymphosarcomatous tissue, acute lymphocytic leukemia cells, and two of the six acute myelocytic leukemia cells. Sedimentation coefficients “S” of the TA-3H macromolecular complex were studied in one of the lymphosarcomatous tumors. When the cells were incubated at 0°, extraction with low-salt buffer produced a 6.5 S TA-3H macromolecular complex, while extraction with high-salt buffer produced a 4 S complex. After incubation at 37°, extraction with high-salt buffer produced a 4 S complex, while extraction with low-salt buffer yielded only a small amount of the complex sedimenting at 6.5 S. However, a 4 S complex was extracted with high-salt buffer from the 27,000 × g pellet of the low-salt extract, suggesting that incubation at 37° resulted in movement of the TA-3H macromolecular complex into the nucleus.

Incubation of HRIK cells in the presence of 10-5 and 10-4m cortisol resulted in 22.5 and 50% inhibition of uridine-3H uptake by the cells, while incorporation of the uridine-3H into cellular RNA was inhibited only after incubation with 10-4m cortisol. The relative insensitivity of these cells to cortisol, despite their high specific-binding capacity, indicate that factors other than steroid binding by the subcellular fractions play an important role in determining the sensitivity of cells to glucocorticoid action.

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