Background. Immunologic abnormalities seem to play an important role in systemic sclerosis (SSc).

Methods. We studied the following immune parameters to get more insight into SSc: autoantibodies (antinuclear antibodies (ana), anti-Scl-70, anticentromere antibodies (aca) subsets of lymphocyte subpopulations and markers of their activation, as well as serum levels of il-2, the soluble il-2 receptor (sil-2r), il-6 and its correlation to N-terminal procollagen-Ill propeptide (piiip), and finally, the il-6 production by SSc and normal dermal fibroblasts.

Results. In patients with active SSc, we found a reduced number of cd2+ T-lymphocytes and an increase in the expression of T-lymphocyte activation markers such as cd25+ and cd71+, hla-dr la, as well as elevated serum levels of sil-2lr and il-6. SSc fibroblasts did not produce more il-6 than normal fibroblasts in monolayer cultures.

Conclusions. Our data show that a wide range of immunologic parameters are altered in SSc. In general, T-helper (th) lymphocytes are activated possibly because of reduced T-suppressor (ts) and natural killer (nk)-cell levels, TH may polyclonally stimulate B cells, which in turn produce higher amounts of autoantibodies. Our findings support the concept that TH cell-derived cytokines/growth factors stimulate matrix protein synthesis by fibroblasts, resulting in generalized fibrosis.