Effect of interleukin‐2 on cell proliferation, sister‐chromatid exchange induction, and nuclear stress protein phosphorylation in Pha‐stimulated fischer 344 rat spleen lymphocytes: Modulation by 2‐mercaptoethanol

Abstract

The effect of interleukin-2 (IL-2) on cell proliferation, sister-chromatid exchange (SCE) frequency, and the phosphorylation of nuclear stress proteins was evaluated in phytohemagglutinin (PHA)-stimulated spleen lymphocytes isolated from Fischer 344 rats. In addition, the ability of 2-mercaptoethanol (2-ME) to modulate the induction of these biological responses was characterized. Cell proliferation, as measured by the mitotic index, increased significantly (P less than .003) from a range of 3-4% in PHA-stimulated cultures to a range of 8-11% in PHA-stimulated cultures exposed to IL-2. The average generation time (AGT) did not respond to IL-2 in a concentration-dependent manner and decreased significantly (P less than .05) when 20 microM 2-ME was included with IL-2 in the culture medium. The number of SCE increased significantly (P less than .004) from control frequencies, which ranged from 13.1 to 15.6 SCE per cell, to frequencies of 18.5 to 21.5 SCE per cell as the concentration of IL-2 in the culture medium increased to 50 half-maximal units per ml. A reduction in SCE frequency was observed when cells were cultured with 20 microM 2-ME and IL-2 compared to IL-2 alone. Three nuclear proteins, with relative molecular masses of approximately 13,000-18,000, 20,000, and 80,000, were phosphorylated in IL-2-exposed G1-phase nuclei. Elicitation of these nuclear proteins in IL-2-exposed cells was not affected by exposure to 2-ME.

Recombinant Human Granulocyte Colony–Stimulating Factor Does Not Influence Distribution or Sister Chromatid Exchange Frequency of Proliferating Mononuclear Cells of the Peripheral Blood

“…The amount of B lymphocytes, natural killer (NK) cells, and CD1 lb+ lym phocytes remained unchanged. As shown previously, PBMC cultured under these conditions are mainly prolif erating T lymphocytes with expression of CD25 and CD71 on their cell surface [20]. Results were given as mean of at least 20 metaphases ± standard deviation; rhG-CSF concentration was given in pg per ml culture medium.…”

“…In no case, an induction of SCE was observed, as it was reported after the administration of cytokines such as IL-2. IFNy and TNF [19][20][21], The weak, insignificant increase of SCE levels at the concentrations 0.03 and 0.3 pg/ml declined to values near control frequencies at the high dose of 3.0 pg/ml with a proliferation index keeping almost the same for all concentrations.…”