Bone marrow cellularity and extent of fibrotic change were determined in nineteen patients with
polycythemia vera, treated with
interferon-alpha (IFN) for 1 year. The cellularity was evaluated with an interactive semiautomatic method using Leitz TAS plus microscope: in particular, number and size of megakaryocytes were evaluated after immunostaining with Y2/51 (CD 61);
reticulin content was studied by light microscope with a semiquantitative method. Before IFN
therapy mean cellularity was 80.5% (+/- 13.7). After 6 and 12 months mean cellularity was 75.4% and 68.4% respectively. Six months after cessation of IFN
therapy the cellularity was 69.1%. A decrease of the number, density and morphometrical parameters of megakaryocytes was also remarked.
Reticulin fibrosis was mild in 13 cases and moderate in 6 cases before IFN
therapy.
Reticulin content was unmodified during
therapy in all cases but two, in which
fibrosis changed from mild to moderate. In conclusion IFN
therapy is to be considered a good method in
polycythemia vera for the control of proliferative activity of bone marrow but with IFN
therapy one cannot determine regression of marrow
fibrosis.