Am. J. Respir. Crit. Care Med., Vol 149, No. 5, 05 1994, 1260-1265.
Interleukin 6 secretion by monocytes and alveolar macrophages in systemic sclerosis with lung involvement
B Crestani, N Seta, M De Bandt, P Soler, C Rolland, M Dehoux, A Boutten, MC Dombret, E Palazzo and MF Kahn
Unite INSERM 226, Hopital Bichat, Paris, France.
Interleukin-6 (IL-6) has been involved in the pathogenesis of inflammatory
and/or autoimmune diseases. We characterized the production of IL-6 by
blood monocytes and alveolar macrophages (AM) in 11 patients with definite
systemic sclerosis (SSc) with lung involvement and in eight normal control
subjects. IL-6 levels were determined in serum, bronchoalveolar lavage
(BAL) supernatants, monocytes, and AM cell culture supernatants using an
ELISA kit. BAL cell analysis evidenced an alveolitis with hypercellularity
and increased neutrophils and mast cells absolute counts. Serum and BAL IL-
6 levels were low and similar in SSc and control groups. The monocytes of
the group with SSc secreted more IL-6 than did the control group, both
spontaneously (p = 0.01) and after LPS stimulation (p = 0.0007).
Spontaneous secretion of IL-6 by AM tended to be higher in the SSc group
than in the control group (p = 0.22). LPS-induced IL-6 secretion by AM was
similar in both groups. Our study demonstrates that during SSc lung
disease, spontaneous and stimulated IL-6 secretion by blood monocytes is
increased, compared with secretion by healthy control subjects. By
contrast, IL-6 secretion by AM is normal despite evidence of mild
alveolitis.
