The CFU-C assay in patients with neutropenia and, in particular, drug associated neutropenia.

One-hundred and four patients with a diagnosis of aplastic anaemia (28) or neutropenia (76) referred to our laboratory for assessment of granulopoiesis were studied. Bone marrow myeloid progenitor cell (CFU-C) frequency was measured and in 85 patients, inhibitor studies with either in-vitro drug addition or plasma co-culture were performed. Of 28 patients with aplastic anaemia, 22 (79%) had low numbers of CFU-C, while four (14%) had numbers within the normal range and two (7%) had elevated progenitor cell frequency. In contrast, of the 76 patients with neutropenia who were studied only 29 (38%) had low CFU-C numbers, 33 (43%) had a CFU-C frequency within the normal range and 14 (18%) had elevated CFU-C numbers. Thirty-nine patients had ingested potentially myelotoxic drugs and in eight of these it was possible to demonstrate drug associated inhibition of CFU-C proliferation in vitro. The drugs most commonly associated on a historical basis with myelosuppression were chloramphenicol, antimalarials, sulphonamides, anticonvulsants and nonsteroidal anti-inflammatory agents.