A nonspecific acute inflammatory reaction, induced in mice by an intrapleural injection of dextran, is able to increase, in vivo, the mitotic index of bone marrow cells. The transfer of this phenomenon to normal mice can be obtained by the injection of pure or diluted sera from animals developing an acute non-specific inflammation. This activity may also be found in the serum of normal mice but at a much lower level. The stimulatory activity is also observable in vitro when bone marrow cells are incubated with inflammatory serum. This activity is recoverable after ultrafiltration in the fraction less than 10 000 daltons. These results suggest the existence in sera of stimulating factors for hematopoiesis and furthermore that these stimulatory activities are increased during the process of inflammation.

Four cases of progressive multifocal leukoencephalopaty are reported, 3 of them with an ultrastructural study and 2 with a C.T. scan study. In 2 cases, there were no other associated pathological condition. In 1 case chronic alcoholism only was present; in the last case a primitive hemochromatosis with a prevailing hepatic dysfunction was evidenced. In 2 of these cases, the initial clinical picture was made of mental disorders while it was made of a progressive left hemiparesis in one case and of a brain stem syndrome in the other case. The results of neuroradiological and isotopical investigations remained negative throughout the evolution in the 4 cases except for some C.T. scan abnormalities. Indeed, in 2 cases the C.T. scan evidenced brain lesions identified as large demyelinated areas. These were low density areas non altered by contrast and unaccompanied by any mass effect. These areas were not seen when the first clinical signs were present and thus, normality of C.T. scan appears not to allow infirmation of the diagnosis of progressive multifocal leukoencephalopathy. In the 4 cases the pathological study showed characteristic lesions of the white matter. Mononucleated cells inflammatory infiltration was observed at the periphery of the demyelinizated regions. This may be related with the primitive aspect of these cases. An ultrastructural study was performed in 3 cases: viral inclusions were present not only in the nucleus of oligodendrocytes but also in their cytoplasm and in some astrocytes.

Neurological and cerebral computed tomography examinations were conducted in 25 infants and young children with uni- or bilateral maxillomandibular neurocristopathies (Goldenhar's, Franceschetti's first arch syndromes or transient forms). Taking all lesions into account, 18 children (82%) presented morphological and motor anomalies of the brain stem (mesencephalus, metencephalus) and its corresponding cranial nerves: four had morphological anomalies of the cerebellum and pons; four presented disorders of bulbopontine control (heart, lungs, deglutition); fifteen demonstrated sensory, sensorial, and motor deficiencies of the paired cranial nerves III, V, VI, VII, and VIII. The high frequency of ocular malformations in this series is emphasized: there were three cases of cryptophthalmia and one case of bilateral iris coloboma. These findings are in agreement with recent acquisitions in the field of cephalic developmental biology: the cephalic neural crest cells, after migration from the mesencephalorhombencephalic neural fold, contribute to the latero-facial and ocular organogenesis. The unity of origin of the face and brain provides an explanation for the predictive role of the former in case of malformations of the brain and its cranial nerves.

The graft of a transplantable leukemia (IW 32) induced by a biologically cloned helper of a Friend virus devoid of SFFV activity, was shown to induce a polycythemia in recipient animals. An in vitro continuous cell line was derived from this leukemia. The supernatant was shown to induce an erythroid differentiation both in vivo in Mice rendered polycythemic by transfusion, and in vitro in plasma clot CFUE assay. This erythropoietic activity was heat stable (30 min. 56 degrees C, 3 min. 100 degrees C) which ruled out the hypothesis that the IW 32 cell line produced a polycythemia inducing virus. The erythropoietic factor produced by IW 32 leukemic cells might be erythropoietin.

Granulocytic progenitor cells (CFC) are a better reflection of stem cell pools than precursors. Their total number can be estimated during hematologic steady-state (N = 70 +/- 29 x 10(5) CFC/kg); the amount of marrow necessary to perform a bone marrow transplantation is only 1% of the total pool. CFC are useful but have a mainly qualitative value in evaluating the viability of marrow stored for 24 h at room temperature (92%) or marrow thawed after DMSO cryopreservation (62%). Sequential study of CFC in patients receiving autologous marrow transplantation enables differentiation of engraftment from autologous recovery. In 11 recipients of autologous marrow transplantation, no statistical relation was observed between number of infused CFC and severity of granulocytopenia. Further studies will be necessary to evaluate a better marker of real hematopoietic stem cells.

This study summarizes a one-year work experience in the area of human tumor stem cells cloning techniques. We found that it was more advisable to use an enzymatic method for dissociating solid tumors. The breast tumors possessing an unfavourable histoprognostic grade were found to grow up more easily in culture, which is a confirmation of known relationships between cell differentiation degree and cell proliferation. The high frequency of failures in the obtention of colonies did not allow to use this technique in daily clinical practice to study the in vitro sensitivity to drugs of a definite tumor. An improvement in the conditions of culture and the comparison with other in vitro methods for the prediction of response to oncostatics--particularly the incorporation of radioactive precursors (Livingston and coll., 1980)--will be attempted in future work.

The mechanisms which regulate cellular differentiation from human pluripotent stem cells to the committed granulocytic and monocytic stem cells (CFU-D, CFU-C) are still imperfectly understood. Most studies involve in vitro and animal experimentations and the relevance of the conclusions on human in vivo mechanisms may be questionable. The monocyte-macrophage system figures actually as the major source of humoral regulators of the normal granulocytopoiesis and monocytopoiesis in man. It produces CSF, a family of glycoproteins which stimulate the proliferation and maturation of CFU-c, and PGE which are inhibitory. In addition, CSF may act as a stimulator of the proliferation and myeloid commitment of CFU-S. Several other humoral factors are of less well established importance. Bacterial toxins and antigens are potent stimulators of the production of CSF. Androgens are stimulators of the proliferation of CFU-C. Lactoferrin, a glycoprotein released by granulocytes, may inhibit CSF production by monocytes-macrophages. CIF, a group of lipoproteins, may act as an inactivator of CSF. Granulocyte chalones and interferon may be inhibitors, though poorly specific, of granulopoietic differentiation. Glucocorticoids may exert an inhibitory effect on CFU-C proliferation and CSF release. Precise analysis of the humoral regulation of normal granulocytopoiesis and monocytopoiesis in man seems to be of critical interest in understanding the pathophysiological mechanisms of blood diseases such as leukemias and aplastic anemias.

We studied the action of cimetidine at various concentrations on human hematopoeitic colony and cluster forming cells "in vitro" (CFUc). Bone marrow samples obtained from 31 patients with various hematological and neoplastic diseases were cultured in semisolid agar. When cimetidine was added to cultures there was a reduction of colony and macrocluster formation. At the concentration used in our study (20 micrograms/ml, 30 micrograms/ml, 40 micrograms/ml) these effects were not dose-related. We did not find any significant reduction of microcluster formation. These results are relevant with the hypothesis that histamine H2 receptors antagonists may have an inhibiting action on bone marrow CFUc proliferation. They point out the need for hematological surveillance during long-term cimetidine therapy.

Two types of basal cells can be identified in the olfactory epithelium: a) the clear basal cells, round in shape, which are true stem cells capable of giving rise to the olfactory and the supporting cells; b) the dark basal cells characterized by a very irregular shape and by the presence in the cytoplasm of numerous mitochondria and bundles of microfilaments. In the aim of interpreting the significance of these dark cells we studied them with the light and electron microscope in the olfactory epithelium of male and female prepubertal and postpubertal rats. The nature of the microfilaments was investigated with the indirect immunofluorescence method for prekeratin and actin. The results show that the basal cells modify their morphology in different endocrine conditions and that microfilaments are made up by actin. Therefore, in our opinion, these cells must be considered as a particular type of supporting cells, capable of directing the cellular movement and arrangement in the olfactory epithelium, when an active cellular turnover occurs.

Twenty patients with Felty's syndrome were investigated. Isotopic studies of polymorphonuclear neutrophils, bone marrow biopsies and autoradiographies, and cultures of granulous stem cells showed that neutropenia resulted from three mechanisms acting simultaneously: hypermargination of the neutrophils predominantly in the spleen, decreased production of granulocytes in the bone marrow, and peripheral hyperdestruction of the neutrophils. Anti-granulocyte antibodies were detected in 3/12 patients. Other factors present in the serum of 2/4 patients seem capable of inhibiting the growth of granulocytic stem cells. Secondary bacterial infection (77%) may explain the severity of the prognosis: 13 out of 27 patients died 4 years on average after neutropenia was diagnosed.

Malignant cells grow selectively in semi-solid media. Cultures of single cell suspensions in these media result in the formation of colonies which are believed to represent clones of stem cells. Cells freshly sampled in cancer patients are assayed in such a system to quantitate the in vitro effect of various anticancer agents vs untreated controls. Partially retrospective comparisons between in vitro and in vivo data are very encouraging and suggest that observations in this assay correlate very favorably with clinical findings. This clonogenic assay should provide an experimental model of special relevance to clinical cancer chemotherapy and should greatly help define optimal treatments in individual patients. Although many technical problems remain to be settled, prospective studies are ongoing to determine to what extent the assay is actually predictive of the response to chemotherapy in cancer patients.

Is has now been well established that osteoclasts are issued from haematopoietic stem-cells and are close relatives of monocytes. However, osteoblasts come from the medullary stroma and are part of the fibroblastic lineage. The precise physiological mechanisms of bone resorption and formation are still unknown, but the numerous experimental studies on this subject recently had an unexpected therapeutic application: human osteopetrosis can be cured by grafts of haematopoietic bone-marrow.

71 bags of bone marrow cryopreserved and stored for periods up to 2 years, were thawed and CFUc recoveries were studied in relation to the rate of freezing following the heat of fusion. Excellent CFUc recoveries (greater than 50%) were obtained in all cases (11/11) for freezing rates smaller than 5 dgC/mn, whereas freezing rates greater than 10 dgC/mn produced poor recoveries in 78% of the cases (4/18). Intermediate freezing rates (5 less than 0 less than 10) resulted in intermediate yields of CFUc, with good recoveries in only 45% of the cases (19/42). These results indicate that CFUc recoveries and subsequently the kinetics of autologous engraftment following the infusion of cryopreserved marrow, which are already known to be related both to the freezing rate before the heat of fusion and the duration of the phase transition period, are also related to this new parameter, which should be carefully monitored during the freezing procedure.

A 66-year-old man presented with a primary malignant lymphoma of the cerebellum and brain stem. The lymphoma was of type V (Bryon's classification) with predominant B cells, and was associated, as in previously reported cases, with a peripheral blood T lymphocyte deficiency. This case was unusual, in that autopsy revealed an active multivisceral sarcoidosis (considered as being cured more than 10 years previously), a clear-cell renal adenoma demonstrating nearly all the characteristics of a Grawitz's tumor, and a papillary epithelioma of the thyroid gland. These findings lead to discuss the significance of immuno-surveillance lack in this particular case: was it dependent on the sarcoidosis (during which a reduction in T lymphocytes is known to occur), or was it primary and perhaps genetic, a son of the patient having Hodgkin's disease? Whatever the case may be, the encephalic proliferation of the B lymphocyte clone, the peripheral epitheliomas, the sarcoidosis, and the deficit in T lymphocytes in the peripheral blood constitute a group of factors singularly rich in questions, this being, apparently, the first case of this type reported in the published literature.

In sublethally irradiated mice, thymus repopulation is due first to the proliferation of surviving thymocytes followed by the multiplication of bone marrow derived prothymocytes. The migration of bone marrow cells to the thymus after a single sublethal whole-body X irradiation was studied by using fluorescein isothiocyanate as a cell marker. Irradiation increases the permissiveness of the thymus to the immigration of bone marrow cells. Furthermore, the post-Rx regenerating bone marrow cells exhibit migration capacities greater than the normal ones. The radiation induced changes in the bone marrow thymus interaction might play an important role in thymus regeneration after sublethal irradiation.

Tumoral stem cells capable of multiplying can be selected from human tumours by in vitro culture techniques. These are the cells which renew the tumour and form metastases. Placed in a suitable agar medium, they give birth to cellular clones. The selection of clone-forming cells from human tumours makes it possible to devise chemograms, as has successfully been done in the U.S.A. by the Salmon and von Hoff teams. Working on a fairly large number of different cancers and using in vitro tests in the presence of drugs, these scientists were able to predict chemosensitivity and chemoresistance in 62 to 96% of tumours. The new techniques and results are presented and discussed.