Calreticulin mutation-specific immunostaining in myeloproliferative neoplasms: pathogenetic insight and diagnostic value.

Mutations in the gene calreticulin (CALR) occur in the majority of JAK2- and MPL-unmutated patients with essential thrombocythemia (ET) and primary myelofibrosis (PMF); identifying CALR mutations contributes to the diagnostic pathway of ET and PMF. CALR mutations are heterogeneous spanning over the exon 9, but all result in a novel common protein C terminus. We developed a polyclonal antibody against a 17-amino-acid peptide derived from mutated calreticulin that was used for immunostaining of bone marrow biopsies. We show that this antibody specifically recognized patients harboring different types of CALR mutation with no staining in healthy controls and JAK2- or MPL-mutated ET and PMF. The labeling was mostly localized in megakaryocytes, whereas myeloid and erythroid cells showed faint staining, suggesting a preferential expression of calreticulin in megakaryocytes. Megakaryocytic-restricted expression of calreticulin was also demonstrated using an antibody against wild-type calreticulin and by measuring the levels of calreticulin RNA by gene expression analysis. Immunostaining using an antibody specific for mutated calreticulin may become a rapid, simple and cost-effective method for identifying CALR-mutated patients complementing molecular analysis; furthermore, the labeling pattern supports the preferential expansion of megakaryocytic cell lineage as a result of CALR mutation in an immature hematopoietic stem cell.

Accentuated response to phenylhydrazine and erythropoietin in mice genetically impaired for their GATA-1 expression (GATA-1(low) mice).

The response of mice genetically unable to up-regulate GATA-1 expression (GATA-1(low) mice) to acute (phenylhydrazine [PHZ]-induced anemia) and chronic (in vivo treatment for 5 days with 10 U erythropoietin [EPO] per mouse) erythroid stimuli was investigated. Adult GATA-1(low) mice are profoundly thrombocytopenic (platelet counts [x 10(9)/L] 82.0 +/- 28.0 vs 840 +/- 170.0 of their control littermates, P <.001) but have a normal hematocrit (Hct) (approximately.47 proportion of 1.0 [47%]). The spleens of these mutants are 2.5-fold larger than normal and contain 5-fold more megakaryocytic (4A5(+)), erythroid (TER-119(+)), and bipotent (erythroid/megakaryocytic, TER-119(+)/4A5(+)) precursor cells. Both the marrow and the spleen of these animals contain higher frequencies of burst-forming units-erythroid (BFU-E)- and colony-forming units-erythroid (CFU-E)-derived colonies (2-fold and 6-fold, respectively) than their normal littermates. The GATA-1(low) mice recover 2 days faster from the PHZ-induced anemia than their normal littermates (P <.01). In response to EPO, the Hct of the GATA-1(low) mice raised to.68 proportion of 1.0 (68%) vs the.55 proportion of 1.0 (55%) reached by the controls (P <.01). Both the GATA-1(low) and the normal mice respond to PHZ and EPO with similar (2- to 3-fold) increases in size and cellularity of the spleen (increases are limited mostly to cells, both progenitor and precursor, of the erythroid lineage). However, in spite of the similar relative cellular increases, the increases of all these cell populations are significantly higher, in absolute cell numbers, in the mutant than in the wild-type mice. In conclusion, the GATA-1(low) mutation increases the magnitude of the response to erythroid stimuli as a consequence of the expansion of the erythroid progenitor cells in their spleen.

Treatment of large cell lymphoma with the Fi2 regimen (doxorubicin, vincristine, cyclophosphamide, bleomycin and prednisone): 25-year experience.

The CHOP protocol is the reference treatment for large cell lymphomas, but several other schemes of different intensity have recently been studied with controversial clinical findings. We report here the results obtained at our institution with a CHOP-like regimen called Firenze 2 (Fi2), which is characterised by an original scheduling of chemotherapy administration. A total of 225 patients, who were diagnosed from 1974 to 1996, were included in this retrospective study. All patients received the Fi2 regimen as a first-line intervention. One-hundred and sixty-two (72%) achieved complete remission; the overall survival at 120 months was 51% with a disease-free survival of 67% (median follow-up = 78 months). The survival curve showed a stable plateau of 42% after 16 years, which remained stable for further 4 years. In a multivariate survival analysis, achievement of complete remission (p<0.001) and IPI index of 0 or 1 (p=0.05) were significantly associated with a better survival. Overall, the outcome of our patients was similar to that reported by others, but the distinguishing feature of our study is the very long follow-up of the patients. Our study confirms that first generation regimens are effective and can cure a substantial proportion of patients. The long-term results of our study are helpful to retrospectively identify high-risk patients whose prognosis is poor and who can be candidates for more aggressive schemes of chemotherapy.

Immunohistochemistry applied to the study of bone marrow Gaucher's cells: a case report.

Gaucher's disease is frequently associated with immunologic abnormalities, e.g. hypergammaglobulinemia, polyclonal gammopathy and benign monoclonal gammopathy. A patient with Gaucher's disease and a selective accumulation of IgM k in Gaucher's cells without serum monoclonal gammopathies is described. The selective accumulation is detected by immunohistochemistry analysis performed on cryostat bone marrow biopsies.