Effect of acute and chronic naloxone treatment on serum IgM anti-KLH antibody response.

Either animals were immunized with 50 μg KLH and killed after 1 week (A) or 2 weeks (C), or they were immunized with 100 μg KLH and killed after 1 week (B) or 2 weeks (D). Results are expressed as mean ± SE of 10 animals per group. * = P < .01 versus saline control.