Abstract
The effects of freezing on phytohemagglutinin (PHA) and lipopolysaccharide (LPS)-induced interleukin-10 (IL-10) production by human peripheral blood mononuclear cells (PBMC) were studied. The freezing process had a divergent effect on the production of IL-10 by PBMC. Frozen PBMC produced significantly smaller amounts of IL-10 in response to PHA stimulation while secreting significantly larger quantities in response to LPS activation. In vitro irradiated PBMC produced significantly smaller amounts of IL-10 in response to both PHA and LPS stimulation. The results indicate that the functional inactivation of a naturally occurring subset of cryosensitive and radiosensitive immunodownregulatory cells is responsible for the observed divergence. They further suggest that, in addition to other mechanisms, a reduction in the secretion of this cytokine synthesis inhibitory factor by the frozen PHA-activated cells could have contributed to the previously reported, augmented IL-2 and IFN-γ-secreting capabilities of frozen PBMC. The significance of this freezing-induced deviation in IL-10 secretion by PBMC in relation to cancer therapy is discussed.
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