The mechanism of benign hereditary neutropenia.

Benign familial (hereditary) leukopenia and neutropenia (BFLN) have been reported in some ethnic groups, including black Americans and Yemenite Jews. The bone-marrow response of 34 Yemenite Jews (with and without neutropenia) to an intravenous injection of 200 mg of hydrocortisone sodium succinate was studied and compared with the response of 18 healthy control subjects. The mean +/- SEM of the increments in polymorphonuclear cells (PMNs) following injection of hydrocortisone in Yemenite Jews (2,413 +/- 245/mm3 in neutropenic subjects and 2,187 +/- 343/mm3 in nonneutropenic subjects) were significantly lower than in the control subjects (4,431 +/- 467/mm3), without significant differences among the subgroups of the Yemenite Jews. The decreases in monocytes, lymphocytes, and eosinophils were similar in all groups. No correlation was found between baseline PMN levels and the increments following hydrocortisone administration. These results suggest a lowered bone-marrow response to hydrocortisone in subjects with BFLN, indicating some defect in PMNs release from the bone-marrow storage pool to the peripheral blood. It seems that this defect characterizes all members of the ethnic group, whether they have "overt" neutropenia or not.