DEPENDENCY ON INTERLEUKIN-1 OF PRIMARY HUMAN INVITRO T-CELL RESPONSES TO SOLUBLE-ANTIGENS

The role of interleukin (IL)-1 in antigen-specific activation of naive human T cells has been examined. Primary human T cell proliferative responses to the soluble antigen keyhole limpet hemocyanin (KLH) were decreased by neutralizing antisera to IL-1-alpha (25 +/- 7 % standard error) and IL-1-beta (56 +/- 6 % standard error). Inhibition by both antisera in a primary culture was usually additive. Recombinant IL-1-alpha and recombinant IL-1-beta could both re-establish responses in cultures blocked by neutralizing anti-IL-1-beta. Interestingly, the susceptibility of KLH-stimulated T cell responses to inhibition by neutralizing anti-IL-1 sera decreased with time in culture.This observation suggested that T cell responses may become less IL-1 dependent as T cells become activated or primed. In support of this notion, secondary T cell responses to purified protein derivative from Mycobacterium tuberculosis (PPD) were markedly less affected by the addition of comparable amounts of the neutralizing anti-IL-1 sera.These results demonstrate that IL-1 is one of the main co-stimulators for primary T cell activation and suggest a different requirement for IL-1 in the activation of naive compared to memory human T cells.