INCREASED NUMBERS OF CIRCULATING BASOPHILS WITH DECREASED RELEASABILITY AFTER ADMINISTRATION OF RHG-CSF TO ALLERGIC PATIENTS

Preliminary studies in hematological patients have indicated that trea tment with rhG-CSF reduces basophil releasability ex vivo. We examined this phenomenon further, in allergic patients. Ten patients with gras s pollen rhinoconjunctivitis were given rhG-CSF (5 mu g/kg/day s.c.) f or 5 days, and examined before and after treatment. Basophil counts in creased from 5 to 19 x 10(9)/1 (P < 0.01). Total blood histamine incre ased from 80 to 160 mu g/l (P < 0.01), corresponding to a decrease in average basophil histamine content from 1.5 to 0.81 pg/cell (P < 0.01) . Isolated mononuclear cells showed a significantly decreased histamin e release (HR) when stimulated with A23187 and grass. Whole blood expe riments showed a similar decreased HR to grass and anti-IgE (P < 0.01) . However, we found an increase in total blood histamine. We conclude that treatment with rhG-CSF (1) increases the number of circulating bl ood basophils, (2) reduces the average histamine content per basophil, and (3) reduces the basophil releasability. These findings could be d ue to the mobilization of immature basophils from the bone marrow.