- The effects of IL-2 on the developing human fetus are unknown. For this reason and because chemotherapeutic agents are known to be teratogenic, participants of child-bearing and child-fathering potential must agree to use adequate contraception (hormonal or barrier method of birth control; abstinence) prior to study entry and for the duration of study participation. Should a female become pregnant or suspect she is pregnant while she or her partner is participating in this study, she should inform her treating physician immediately. Males treated or enrolled on this protocol must also agree to use adequate contraception prior to the study, for the duration of study participation, and 4 months after completion of IL-2 administration.