CYTOKINE PRODUCTION BY CRYOPRESERVED HUMAN PERIPHERAL-BLOOD MONONUCLEAR-CELLS IN RESPONSE TO PERIODONTAL PATHOGENS

Freezing techniques provide a way of repeating and extending immunolog ical assays by using frozen portions of an individual's peripheral blo od mononuclear cell fraction. Earlier work shows that the lymphocytes that are stored frozen retain their ability to respond to polyclonal B -cell activators, mitogens, superantigens and bacterial extracts of or al interest. These studies extend previous findings by determining cyt okine production by lymphocytes following frozen storage for up to 24 weeks. Production of interleukin (IL)-1 beta, IL-2, IL-6, and tumour n ecrosis factor (TNF)-beta by stimulated lymphocytes after cyropreserva tion was not significantly different from those responses before stora ge, with one exception: IL-6 production was negligible after 24 weeks' frozen storage when thawed cells were cocultured with pokeweed mitoge n. After stimulation with extracts from Porphyromonas gingivalis and A ctinobacillus actinomycetemcomitans, the proliferative capacity of the frozen cells was maintained as well as the production of IL-1 beta, I L-2, and IL-6. TNF-beta was not produced in response to bacterial anti gen stimulation. The ability of peripheral blood mononuclear cells to retain functional activity after frozen storage should permit more eff ective monitoring during longitudinal clinical studies and a better ev aluation of changes in cytokine production in patients with advanced p eriodontitis both during and after treatment. (C) 1998 Elsevier Scienc e Ltd. All rights reserved.