GROWTH OF CHLAMYDIA-PNEUMONIAE IN CULTURED HUMAN PERIPHERAL-BLOOD MONONUCLEAR-CELLS AND INDUCTION OF A CYTOKINE RESPONSE

In vitro infection of freshly isolated human peripheral blood mononucl ear cells (HPBMC) with Chlamydia pneumoniae was found to induce a prod uction of tumour necrosis factor alpha (TNF-alpha), interleukin-1 beta (IL-1 beta), interleukin-6 (IL-6) and interferon alpha (IFN-alpha). T he secretion was dependent on the amount of infecting chlamydiae and m ost of it occurred during the first 12 to 24 h. Lipopolysaccharide (LP S) of Salmonella minnesota Rechemotype, used as a positive control for HPBMC activation, induced a release of TNF-alpha, IL-1 beta and IL-6, but not of IFN-alpha, similar to the effect of C. pneumoniae. Viable chlamydiae could not be recovered from HPBMCs infected immediately aft er their isolation, whereas HPBMCs which were cultured in vitro for 3 to 9 days before infection were able to maintain the growth of C. pneu moniae. Growth inside HPBMCs as well as induction of cytokine response may have a role in the pathogenesis of C. pneumoniae infection. (C) 1 996 Academic Press Limited