IFNG and tetanus: Multiple individual seminal fluid samples diluted out to 1:200 or more suppressed proliferation of CD4+ T cells in response to tetanus, determined by dilution of CFSE dye labelled PBMCs (Figure 2A) and suppression of IFN-γ production by PBMCs in response to tetanus, determined by ELISpot assay (Figure 2B).