CTLA4 and Hodgkins lymphoma: Also, the downregulatory molecule cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) was shown to play a possible role, as the proportion of CTLA-4+/CD3+ cells negatively correlated with proliferative activity, IL-2 and IFN-gamma production by T lymphocytes in HL patients [31].