Colony-forming cells in culture and colony-stimulating activity of the urine and the serum in a case of cyclic neutropenia.

A 22-year-old female with cyclic neutropenia was studied. Her bone marrow cells showed high colony-forming activity in soft agar through the cycle, though there were slight fluctuations in the number and the shape of colonies. On the other hand, the peak of urinary colong-stimulating activity (CSA) occurred at the neutropenic stage. The dialyzed serum showed two peaks of CSA, i.e., at the peak and the valley of the neutrophil count, although the undialyzed serum showed only one peak at the neutroenic stage. It is suggested on the basis of these data that humoral factors may play a role in maintaining the neutrophil cycle.