IFNG and neoplasm: In order to clarify whether this modulation was systemic, cytokine secretion was also quantified in in vitro cultures of spleen cells, stimulated with L. casei. Higher levels of secreted IFN-γ were observed when spleen cells, isolated from mice three (d13 from start) or seven (d17 from start) days post tumor cell inoculation, were cultured in vitro in the presence of 108 CFU/mL of L. casei for 48 h.