Assessment of peripheral blood lymphocyte subsets in idiopathic myelofibrosis

The objective of this study was to contribute to a better characterization of the immunological profile of idiopathic myelofibrosis (IM) at presentati on by analysing the blood lymphocyte subsets and their possible correlation s with other disease features. Absolute blood lymphocytes and lymphocyte su bsets were assessed in 31 IM patients, compared with those from 34 healthy individuals, and correlated with the patients' main clinical, hematological and bone marrow histologic features. The mean lymphocyte count of the IM p atients was 1.1 (SD 0.6) x 10(9)/L, versus 1.6 (SD 0.49) x 10(9)/L in contr ols (p = 0.0006), with 24 of the 31 patients (77.4%) showing lymphocytopeni a ( <1.5 x 10(9)/L). IM patients had significantly lower counts of CD3, CD4 , CD8, and CD3 -/ CD56+ cells, and significantly higher CD3+/CD56+ lymphocy te counts. Although no significant differences were found between patients and controls with regard to CD19+/CD5+ cell counts, increased CD5+ B-cell l ymphocytes were observed in three IM patients. In one of the latter patient s, Ig gene rearrangement analysis of the heavy chain gene demonstrated such a subpopulation to be clonal, but the patient did not develop features of chronic lymphoid leukemia during a 5-yr follow-up. No correlation was found between the patients' blood lymphocyte counts and other disease features. We conclude that most IM patients have absolute lymphopenia, decreased T ce lls and increased cytotoxic T cells at diagnosis, and 10% of them show an i ncreased CD5+ B-cell subpopulation.