CD4 and systemic sclerosis: Interestingly, an overwhelming presence of CD4+ T cells, type 2 T helper (TH2) cells known to secrete IL-4 and IL-13 and to a lesser extent TH1 cells, which primarily secrete anti-fibrotic interferon γ (IFNγ) was detected as part of the cellular infiltrate in SSc biopsy samples of skin (12).