Effects of Cryopreservation on Immune Responses

Abstract

In view of the wide usage of frozen PBMCs as stem cell support following high-dose chemo- and/or radiotherapy, and the pleiotropic activities of tumor necrosis factor-α (TNF-α), the influences of freezing and radiation on LPS-induced TNF-α production by human peripheral blood mononuclear cells (PBMCs) were studied. Frozen PBMCs secreted significantly larger quantities of TNF-α than fresh cells. Blocking of endogenous IL-10 by neutralization with anti-IL-10 monoclonal antibody resulted in further augmented and prolonged secretion of TNF-α by both the fresh and frozen cells. In contrast, addition of exogenous IL-10 to LPS-stimulated cultures inhibited TNF-α secretion.In vitroirradiation had an inconsistent effect on TNF-α production by the fresh PBMCs. Taken together, these results suggest that the endogenously hypersecreted TNF-α is indirectly responsible for the previously reported elevated IL-1-, IL-6-, and IL-10-secreting capabilities of frozen PBMCs. They also indicate that the TNF-α induced IL-10 and then down-regulates the monocytes from further TNF-α secretion. Considering the vital role played by TNF-α in antimicrobial and antitumor activities, in the immune system, and in the pathogenesis of many acute and chronic diseases, the abilities of frozen cells to produce large quantities of TNF-α in response to infectious agents could have profound impact on patients receiving such frozen PBMCs as stem cell support following myeloablative therapies.