In light of the findings in this study, and given the fact that GVHD involves gastrointestinal tract injury, with concomitant release of gut microbiota, we can speculate that a fraction of the Lag-3 expressing Tcon would convert into CD4+CD25−Lag-3+ regulatory T cells that would suppress to some extent donor T cell proliferation which could lead to an alleviation of GVHD symptoms. The gene discussed is CD4; the disease is graft versus host disease.