Functional analysis of T lymphocytes infiltrating the dermis and epidermis of post-burn hypertrophic scar tissues

The cytokine profile of T cell clones (TCC) from the dermis and epidermis of burn patients with hypertrophic scars (HS) in active (AHS) and remission phases (RHS) was determined in this study. We found that AHS tissues are heavily infiltrated by Type 0–Type 1 polarized CD3+ lymphocytes producing high IFN-γ and low IL-4 levels. Analysis of their surface marker phenotype showed that the high IFN-γ production was shared equally between the CD4+TCRα/β and CD8+TCRα/β clones. The profile of TCC from RHS tissues revealed pronounced infiltration of Type 0–Type 1 polarized lymphocytes with an even more evident Type 1 profile. However, the levels of IFN-γ produced by RHS-derived TCC were 4–6 times lower than those produced by AHS-derived TCC. These data show that high levels of IFN-γ produced by Type 0–Type 1 lymphocytes infiltrating HS are a feature of AHS, whereas reduction of this ability to produce high levels of IFN-γ, though without a shift towards a Type 0–Type 2 phenotype through an increase in IL-4, is characteristic of RHS.