Activation of IL‐6 production by UV irradiation of blood mononuclear cells from patients with systemic lupus erythematosus

SUMMARY Cultured mononuclear cells from patients with systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), and normal donors were assayed for their ability to secrete IL‐6 both spontaneously and after exposure to UV light. Mononuclear cells from SLE, RA and atopic control patients produced IL‐6 spontaneously, while those from normal donors did not. Spontaneous production of IL‐6 occurred in the non‐adherent cell population. UV light‐induced IL‐6 production was confined exclusively to the SLE patients and was present only in the macrophage/monocyte fraction. This stimulation was induced by wavelengths in the UVA, UVB but not the UVC portion of the spectrum. These results suggest that cytokine release may be involved in the exacerbations of SLE provoked by photosensitivity.