A 3½-yr-old boy with infantile genetic agranulocytosis (IGA) has had recurrent infections since the age of 3 mo. Characteristically he shows permanent, almost complete neutropenia with relative monocytosis in the peripheral blood, together with a bone marrow rich in proliferative myeloid cells, but lacking in mature ones. Results of in vitro cloning of the patient’s bone marrow cells in soft agar indicate that human-spleen-conditioned medium can induce the formation of large granulocyte colonies with normal maturation. The cloning efficiency, colony size, and degree of maturation were no less than in cultures seeded with normal marrow cells. Neither the addition of patient’s serum to normal marrow culture, nor the addition of normal serum to patient’s marrow culture, caused any change in cloning efficiency or degree of maturation. These observations suggest that precursors of granulocytes in cases of IGA are potentially capable of normal proliferation and maturation provided that they are supplied with an inducer such as that derived from human spleen.

  • Submitted December 4, 1970.
  • Revision received February 15, 1971.
  • Accepted February 19, 1971.