Felty's syndrome is characterized by neutropenia, splenomegaly, and recurrent infection in patients with rheumatoid arthritis. We Used recombinant granulocyte colony stimulating factor (rGCSF) in a patient with Felty's syndrome and recurrent sepsis. rGCSF induced a statistically significant increase in the patient's absolute neutrophil and total white blood cell counts. During 14 months of followup taking rGCSF, disseminated varicella zoster was the only infectious complication. Except mild thrombocytopenia and a transient flare of arthritis, no serious adverse effects occurred. rGCSF may be a safe and effective therapy for Felty's syndrome in selected patients.

(ENGLISH) Hematopoiesis is dependent on the actions of hematopoietic stem cells (HSCs). This process is tightly controlled through a complex array of extrinsic and intrinsic factors. Even though the hematopoiesis seems to be well conserved across the disparate vertebrate animals, erythroid and thrombocytic differentiation have changed during the evolution of mammals. Specifically, adult mammalian red blood cells have the unique feature of being enucleated, and mammalian thrombocytes are not individual cells, but fragments of megakaryocytes, instead. It is likely that these enhancements provided a survival advantage to early mammalian species; however, they also bring up the question of evolutionary origin of these cells that studied using zebrafish (Danio rerio) model. First, it was necessary to generate a toolbox of a recombinant cytokines and optimized culture media that allowed us to manipulate zebrafish hematopoietic cells ex vivo in liquid and clonal cultures. Interestingly, teleost species underwent an extra duplication event during their evolution and as a result, two copies (paralogs) of some of the genes are present in zebrafish. This was also the case for majority of the cytokines from our toolbox and here, we provide functional characterization of these paralogs. Strikingly, our results...