Cytofluorimetric and functional analysis of c-kit receptor in acute leukemia.

The SR-1 monoclonal antibody (MoAb) recognizes an epitope of the c-kit receptor (KR), present on normal hemopoietic CD34+ stem cells as well as on blasts from patients with acute leukemia. Cytometric analysis by indirect immunofluorescence with the SR-1 MoAb was performed in 98 patients with acute myeloblastic leukemia (AML) and in 37 patients with acute lymphoblastic leukemia (ALL) in order to detect the presence of the KR and to examine its prognostic significance. Sixty-nine of 98 (70%) AML patients were SR-1 positive independently of the FAB subtype, although a higher incidence of SR-1 positive cases was observed in M4 and M5 AML and in those cases that also coexpressed lymphoid antigens. Fourteen AML samples were studied by Northern blot analysis and the KR mRNA was detected in the majority of SR-1 positive cases and also in 2 of 3 SR-1 negative samples. Furthermore, "in vitro" cultures from 15 cases showed that recombinant human Stem cell factor (rhSCF) induced an increased proliferative activity in most tested cases (11/15); this was further enhanced when rhSCF was combined with rhIL-3 + rhGM-CSF (p = 0.007) and with the GM-CSF/IL-3 fusion protein PIXY321 (p = 0.003). Thirty-seven ALL cases were also studied and all but one were SR-1 negative. Interestingly, the only SR-1 positive case also coexpressed myeloid antigens and showed an "in vitro" response when stimulated with rhSCF. Finally, the complete remission (CR) rate, survival and event-free survival were evaluated in 75 AML patients who received standard and identical chemotherapy; unlike previous studies which utilized a different anti-KR MoAb (YB5.B8) and which showed a poor prognosis for KR positive patients, we were unable to document any significant difference in CR rate, survival and event-free survival.

Production of interleukin 6, leukemia inhibitory factor and granulocyte-macrophage colony stimulating factor by peripheral blood mononuclear cells in Fanconi's anemia.

The aim of this study was to test the in vitro cytokine production by peripheral blood mononuclear cells (PBMCs) in patients with Fanconi's anemia (FA). Phytohemagglutinin (PHA)-stimulated PBMCs from 21 patients with FA were studied for their ability to produce interleukin 6 (IL-6), leukemia inhibitory factor (LIF) and granulocyte-macrophage colony stimulating factor (GM-CSF). Enzymatic immunoassay (EIA) was used for both IL-6 and LIF, while GM-CSF was evaluated in a highly sensitive biological assay provided by GM-CSF-dependent M-07e cells. A significant decrease of IL-6 was detected in 9 out of 11 FA patients compared with five normal donors, while similar amounts of LIF were produced from 21 FA patients and 21 healthy subjects. A drastic increase of active GM-CSF was documented in PHA-stimulated PBMC-conditioned medium in all 18 FA patients tested. Since IL-6 and GM-CSF play an important role in maintaining basal hemopoiesis, our results suggest that an abnormal cytokine network may be involved in the pathogenesis of FA pancytopenia.

[Ultrastructural changes in myocardial anoxia and reoxygenation]. / Modificazioni ultrastrutturali in corso di anossia miocardica e riossigenazione.

The aim of this study is to describe the ultrastructural changes in anoxic rat hearts perfused with Langendorff technique and the effects of reoxygenation on myocardial cells. After 1 h of aerobic perfusion, the hearts were subjected to 30 min of anoxia and then to 5 and 30 min of reoxygenation. The following findings were observed: after 30 min of anoxia, loss of mitochondrial matrix and dilatation of the intracristal spaces. After 5 min of reoxygenation: diffuse mitochondrial swelling, sarcomeres disarranged and out of register, several contraction bands. After 30 min: no evidence of cytoplasmic or mitochondrial swelling. The maximum enzyme release was observed when a wide myofibrillar contraction occurred. These results may suggest that the oxygen availability consequent to myocardium anoxia lead to further cell damage.

[Ribosome crystallization in the in vitro differentiation of chick embryo epidermis]. / La cristallizzazione ribosomiale nel differenziamento in vitro di epidermide di embrione di pollo.

Six day chick embryo thigh skin has been incubated for 2, 3 or 6 days in media containing either chick embryo extract or chick serum, than submitted to hypothermia for 36 hours to induce the formation of ribosome crystals. The results show that it is possible to relate the crystallization with the different degree of differentiation attained in each experimental condition.

[Ribosomal crystallization in the in vitro differentiation of mesenchymal cells interacting with the epithelium]. / La cristallizzazione ribosomiale nel differenziamento in vitro delle cellule mesenchimali interagenti con l'epitelio.

Ribosomal crystallization of 6-day chick embryo thigh skin in vitro in two different nutrient media was studied. The embryo thigh skin has been incubated for 3 or 6 days in media containing either chick embryo extract or chick serum, than submitted to hypothermia for 36 hours to induce the formation of ribosome crystals. The crystals are present in almost all type of cells in E medium, while in the cells in CS medium only after 3 days; therefore it is possible to relate the crystallization with the different degree of differentiation attained in mesenchymal cells.

[Effects of ionizing radiations on the ultrastructure of bursa of Fabricius]. / Effetti delle radiazioni ionizzanti sulla ultrastruttura della borsa di Fabrizio.

The alterations induced in the lymphoid and epitelial cells of the Bursa of Fabricius in chicks exposed at different doses of gamma rays mainly occur during the interfase. The extent of these alterations appears reduced in comparison with that observed in the chick thymus treated in the same way.

[Effects of ionizing radiations on the ultrastructure of the thymus gland]. / Effetti delle radiazioni ionizzanti sulla ultrastruttura del timo.

Different doses of gamma rays induce ultrastructural alterations in limphoid and epithelial cells of the chick thymus which exhibit a different temporal evolution after the treatment. The main changes which occur in lymphoid cells treated with 50 rads disappear 48 hours after the irradiation, while with 100 rads the radiation damage is still evident in epithelial cells.

An ultrastructural analysis of chick embryonic skin development in vitro.

Behaviour of 6-day chick embryo thigh skin in vitro in two different nutrients was studied electron microscopically. In explants supported with chicken serum containing medium epithelium keratinized faster than and in a similar way to that in ovo, except for the absence of corpuscola cribriformia in pericytes. It did not in explants supported with chick embryo extract containing medium, but underwent a noticeable ultrastructural evolution, mainly of granular reticulum and Golgi complexes. In the two series of cultures mesenchyme presented the same ultrastructural characteristics, especially as far as collagen fibers were concerned. The above data rule out the suggested regulatory role of collagen fibers in epidermal differentiation and support a possible epidermal two-step differentiative process. They are discussed in relation to the general mechanisms implicated in skin evolution.