It was suggested that the immune system plays an important role at least in the amplification of the main elements in systemic sclerosis (SSc), an autoimmune disease with an incompletely elucidated pathogenesis. Elucidation of the mechanisms involved in the interaction between T and B cells, major players of the immune system, could contribute to a better understanding of some of clinical and pathological manifestations of SSc. Recently, abnormalities in Semaphorin 4D (Sema4D/CD100) or CD72, two contrareceptors involved in T and B cells cooperation, were associated with autoimmunity. Therefore, we investigated CD100 and CD72 expression level on T and B cells in attempting to establish their role in SSc pathogenesis. The results revealed augmented percentages of CD100(high) T and B cells, significantly increased expression of CD100 on CD4(+) T cells and frequently detectable levels of soluble CD100 in SSc patient sera compared to healthy donors. In SSc, CD100 dysregulations were associated with anti-Scl70 antibodies production, disease type, thickening of skin, disease duration, or with active inflammation processes. In consequence, dysregulations in CD100 expression and release could play a role in SSc development and/or maintenance.