IMPROVED VACCINATION RESPONSE DURING RANITIDINE TREATMENT, AND INCREASED PLASMA HISTAMINE CONCENTRATIONS, IN PATIENTS WITH B-CELL CHRONIC LYMPHOCYTIC-LEUKEMIA

Patients with B cell chronic lymphocytic leukemia (B-CLL) have decreas ed capacity to mount relevant antibody responses upon immunization, an d development of hypogammaglobulinemia is part of the natural history of the disease. We investigated the influence of histamine type-2 (H2) receptor blockade by ranitidine on the in vivo antibody production in B-CLL patients following vaccination. Anti-polysaccharide antibodies in B-CLL patients, vaccinated with a tetanus-toroid conjugated vaccine against Haemophilus influenzae type-B (Hib), reached longterm protect ive levels in more than 90% of B-CLL patients randomized to ranitidine treatment, as compared to 43% of the untreated patients (P = 0.024). No difference in the response to vaccination against Influenza virus t ypes A and B protein could be detected between the two groups. Plasma histamine levels were 2-fold to 20-fold higher in 23 out of 31 B-CLL p atients, compared to normal controls, and these levels showed a signif icant positive correlation to disease duration. These findings indicat e the possibility of improving in vivo antibody production against a h ighly relevant pathogen in B-CLL patients by histamine type-2 receptor blockade, and the combined finding of an immune-stimulatory effect of ranitidine and increased plasma histamine levels, strongly suggests t he involvement of histamine in the pathogenesis of B-CLL immunodeficie ncy.