Lymphocyte subpopulations in peripheral blood and bone marrow in patients with idiopathic myelofibrosis.

In 8 patients with idiopathic myelofibrosis (IM) T and B cells were studied in view of the possibility that immunological dysfunctions are involved in initiating or contributing to the bone marrow fibrosis. In peripheral blood the absolute numbers of E-SRBC and OKT3+ lymphocytes were significantly reduced; in addition a significant decline was observed in the proportion and absolute numbers of OKT8+ cells, resulting in a reversed Leu-3a/OKT8 ratio. An impaired B cell function was observed in 4 of the 8 patients, characterized by a disturbed in vitro pokeweed mitogen stimulated immunoglobulin synthesis and low serum immunoglobulin levels. Immuno-histological studies of the bone marrow demonstrated a scarcity of T cells but normal numbers of B cells. However, no correlation was noted between the observed deviations of B and T cells and the degree of bone marrow fibrosis determined by means of bone marrow histology and serum procollagen-III levels. These data are not sufficient to support the hypothesis that immunological changes in IM are primarily involved in the process of bone marrow fibrosis.