T-CELL HYPERREACTIVITY TO IL-6 IN CHRONIC NONVIREMIC HBV CARRIERS DESPITE NORMAL IL-6 RECEPTOR OR GP130 EXPRESSION

We previously showed that T cells from chronic nonviremic HBsAg carrie rs activated with immobilized OKT3 MAb are hyperreactive to monocyte a ccessory signals, mainly to interleukin-6 (IL-6). We have further char acterized this T cell hyperreactivity using phytohemagglutinin (PHA) a s the primary activating signal. PHA-stimulated T cells from non-virem ic patients had a significantly higher response to addition of monocyt es, monocyte supernatants, and IL-6 alone or combined with IL-1 beta w hen compared to controls. We examined if these effects could be mediat ed by a differential expression of IL-6 receptor (p80) or gp130 on res ting or PHA-stimulated T cells. We found that PHA, IL-6, IL-1 beta, or IL-2 induced only small changes of the dull p80 expression on T cells . In contrast, we found a significant increase of gp130 expression on PHA-activated T cells compared to unstimulated T cells, which was down -regulated by the presence of IL-6. However, no significant difference s in p80 or gp130 expression were detected between patients and contro ls within all the culture conditions tested. Our results confirm that IL-6 is involved in the in vitro T cell hyperreactivity of nonviremic HBV carriers and indicate that this effect is not mediated by disturba nces of IL-6 receptor expression.