Established macrophagelike cell lines synthesize interleukin-1 in response to toxic shock syndrome toxin.

Toxic shock syndrome toxin is already known to induce the production of interleukin-1 (IL-1) by preparations of monocytes and macrophages that are presumably contaminated with other types of cells. The response is enhanced by increasing the density of such monocytes, suggesting that the monocyte's response to toxic shock syndrome toxin may be augmented by its interaction with some other cell. Nevertheless, we now show that several human and murine macrophagelike cell lines (U937, J774, P388D1, and WEHI 3) produce IL-1 when exposed to toxic shock syndrome toxin, and therefore the basic response does not require the presence of cells of other lineages. The cultured cells generally produce less IL-1 than do monocytes, but considerably more IL-1 is induced from cells that have undergone a terminal differentiation as a result of exposure to 1 alpha,25-dihydroxyvitamin D3. High concentrations of cultured cels suppress the production of IL-1; this effect is apparently not due to long-lived inhibitors of IL-1 production or of IL-1 activity, but may be due to a short-lived inhibitor of production.