Anti–IL-7Rα antibody treatment results in increased anti-SRBC titer following immunization. Anti-SRBC agglutinating titers were measured 1 week after the primary immunization (at day 44) and the secondary immunization (at day 58) after BMT. Asterisk indicates significant differences between PBS- and anti–IL-7Rα–treated allogeneic BMT-plus-LN recipient groups (P < .006).