Establishment and characterization of continuous hematopoietic progenitors-derived pig normal mast cell lines.

Mast cells (MCs) are tissue resident, hematopoietic stem cells-derived elements, distributed throughout the body. They are the pivotal mediating cells of allergic reactions. In addition, in mice, MCs play a critical role in the defense against several pathogens, such as bacteria, parasites and viruses. Whereas the biology of rodent and human MCs has been extensively studied using in vitro derived populations, the role of MCs in pigs has not yet been evaluated, given the very low availability of pure porcine MCs populations. In the present report, we describe an original method to obtain continuous factor-dependent normal pig MCs (PMC) lines from fetal hematopoietic progenitors. These Stem Cell Factor (SCF) and Interleukin-3- (IL-3)-dependent PMC lines retain their capacity to growth after conventional freezing methods and exhibit most of the morphological and biochemical properties of normal, although immature, MCs, including metachromatic granules containing sulfated polysaccharides, the expression of c-kit and high-affinity IgE receptors (FcepsilonRI), and the ability to store histamine that is released upon cross-linking of FcepsilonRI. In vitro derived PMC lines might thus be valuable tools to further investigate the reactivity of these elements towards several parasites frequently encountered in pig, such as, but not limited to, Ascaris suum, Trichinella spiralis or Trichuris suis, or towards antigens derived from these pathogens.

Establishment and characterization of a new human erythroleukemic cell line, ERY-1.

The growth factor-independent erythroleukemic cell line ERY-1 was established from the peripheral blood of a 87-year-old woman with chronic myeloid leukemia (CML) in the acute phase. Immunophenotyping showed that fresh leukemic cells were positive for CD13, CD33, CD36 and CD235a (glycophorin A), a phenotype compatible with that of erythroblastic cells. Cytogenetic and fluorescence in situ hybridization (FISH) analysis demonstrated classical t(9;22)(q34;q11) chromosomic translocation associated with a duplication of the BCR-ABL fusion gene. Other cytogenetic abnormalities were detected in all analyzed mitosis, the most frequent being a trisomy of chromosome 8. The established ERY-1 cell line retains these immunophenotypic and cytogenetic features, and light and electron microscopy confirmed the relatively mature erythroblastic phenotype of the cells. In addition, ERY-1 cell line expressed beta-globin mRNA and a non-phosphorylable form of the erythropoietin receptor, even in presence of erythropoietin. Of note, the proliferation of ERY-1 cells was inhibited by TGFbeta1 or STI-571 (Gleevec), without significant induction of further differentiation. In conclusion, ERY-1 is a new growth factor-independent human erythroleukemic cell line with a relatively mature phenotype that may be useful to study the molecular events involved in erythroblastic differentiation.

Kit and c-kit mutations in mastocytosis: a short overview with special reference to novel molecular and diagnostic concepts.

Mastocytosis is a heterogeneous group of hematopoietic disorders characterized by abnormal growth and accumulation of mast cells (MC) in one or more organs. Clinical symptoms occur as a result of the release of chemical mediators and/or of pathologic infiltration of MC in various tissues. Although the initial events leading to mastocytosis have not yet been unraveled, acquired alterations in the c-kit gene coding for the receptor of stem cell factor (SCF), a major cytokine involved in MC growth, have been described in a significant number of patients. Of particular interest are point mutations resulting in a constitutively activated SCF receptor. Such mutations are probably involved in the abnormal (SCF-independent) proliferation of MC in these patients. New therapeutic strategies may be envisaged to inhibit the deregulated kinase activity of these mutant forms of c-kit.