Evidence That X-Irradiation and 4-Hydroperoxycyclophosphamide Affects Different Lymphocytes That Respond to Specific Antigen In Vitro

Abstract

The present study examined the effect of pulse treatment with the in vitro active synthetic derivative of cyclophosphamide (CY), 4-hydroperoxycyclophosphamide (4-HPCY), and exposure to X-irradiation on the in vitro Concanavalin A (ConA), lipopolysaccharide (LPS), and antigen-specific blastogenic responses of in vivo-primed lymph node cells. Primed lymph node cells from CY-pretreated, aggregated (A) human IgG-complete Freund's adjuvant (AHGG-CFA)-immunized mice were untreated, exposed to various doses of irradiation, or pulse treated with different concentrations of 4-HPCY before being cultured in medium alone or in medium containing HGG, ConA, or LPS. The results show that HGG-responding and LPS-responding cells exhibited similar dose-inactivation profiles following exposure to irradiation or pulse treatment with 4-HPCY. More than 75% of reactivity was eliminated by exposure to 100 rads or pulse treatment with 20 microM 4-HPCY. In contrast to preculture pulse treatment with 4-HPCY, however, when primed lymph node cells were cultured in medium containing 4-HPCY (culture treatment) LPS-responding cells were shown to be more sensitive to inactivation than HGG-responding cells. The data further show that the effect of low-dose irradiation and of culture treatment with 4-HPCY on the HGG-specific response of primed lymph node cells was additive, suggesting that these agents inactivate different cell subtypes that contribute to the HGG-specific response in vitro.