[In vitro activity of folic acid on the proliferation dynamics of human bone marrow CFU-GM in propyphenazone-induced granulocytopenia].

The in vitro action of folic acid was tested on the proliferation of bone marrow granulocyte-macrophage progenitor cells from a patient with drug-induced (propyphenazone) neutropenia in remission 20 days after the drug had been suspended. Various bone marrow cultures were prepared with standard stimulant, adding, respectively: folic acid, propyphenazone and both folic acid and propyphenazone together. Growth was tested on day 7, 12 and 19 of incubation. Under baseline culture with standard stimulant, CFU-GM growth was characterized by successive proliferation waves of various entity: the first on day 7 was very high, the second, on day 12 was rather low, and the third, on day 19 was intermediate. This behaviour is different from what is usually observed in normal subjects in steady-state, whose first (AC-A+AC-B) and second (AC-C) proliferation period are of similar entity. The prevalence of the first proliferation period in our case is interpreted as the result of a renewed granulocytopoietic activity after drug-induced bone marrow suppression. This indicates a maintained integrity of the negative-feedback mechanism of homeostatic regulation on granulocytopoietic activity. The sole addition of propyphenazone on the in vitro bone marrow cell cultures of our patient produced a reduction of those CFU-GM that had grown during the first period whereas the growth during the second and third period remained unvaried. Thus the growth peak in cultures treated with propyphenazone occurred on day 19, which seems to correspond with the necessary time for a spontaneous remission from neutropenia, clinically observed to be 20 days after suspension of the propyphenazone-containing drug.(ABSTRACT TRUNCATED AT 250 WORDS)