text: Culture of CD4+ T cells
  PB CD4+ T-cell populations were resuspended at a density of 1 x 106 cells/ml in culture medium with 10% FCS, and 0.5 ml cell suspensions were dispensed into the wells of 24-well microtiter plates (Coster) coated with 1 mug/ml anti-CD3 mAb (Immunotech, Marseille, France). The cells were incubated with 1 mug/ml anti-CD28 mAb (Immunotech) in the presence or absence of the indicated concentrations of IL-10 (Becton Dickinson, San Jose, CA, USA) at 37degreesC in a humidified atmosphere containing 5% CO2 [28]. Culture supernatants were collected 36 hours later and cell-free samples were stored at -30degreesC until cytokine assay. 
  To examine the effect of IL-6 on T-cell responsiveness to IL-10, CD4+ T cells from healthy controls were incubated in culture medium with 10% FCS in the presence or absence of 10 ng/ml IL-6 (Becton Dickinson) for 36 hours. Cells were then stimulated for 36 hours with anti-CD3 mAb and anti-CD28 mAb in the presence or absence of 1 ng/ml IL-10. Culture supernatants were measured for IFN-gamma concentrations. 
  