INTERLEUKIN-6 IN NEUTROPHILS FROM PERIPHERAL-BLOOD AND INFLAMMATORY PERIRADICULAR TISSUES

Periradicular tissue samples were recovered recovered from patients un dergoing endodontic surgery. Immuno-histochemical procedures were used to identify interleukin-6 (IL-6) present in the neutrophils associate d with these lesions. Using specific polyclonal antibody, 15 to 20% of the neutrophils associated with the periradicular tissue lesions were positive for IL-6. IL-6-positive plasma calls and histiocytes were al so abundant. Cytokine production by neutrophils from the peripheral bl ood of nondiseased individuals was also evaluated. The cells were stim ulated with lipopolysaccharides and bacterial extracts of Actinobacill us actinomycetemcomitans and Porphyromonas gingivalis. Significant lev els of IL-6 were produced by cells stimulated with Escherichia coli li popolysaccharide B5 (933 pg/ml/10(7) neutrophils) and E. coli lipopoly saccharide B12 (791 pg/ml/10(7) cells) when compared with unstimulated cells (39.31 pg/ml/10(7) cells). There was a dose-dependent increase in IL-6 production when cells were stimulated for 24 h with 6 and 12 m u g/ml of A. actinomycetemcomitans extract. Less stimulation occurred with P. gingivalis, but it was also dose-dependent. Neutrophils reside nt in periradicular lesions may, therefore, provide a source of IL-6 i n addition to that produced by tissue histiocytes and plasma cells.