Immunocompetent cells in the starfish Asterias rubens. An ultrastructural study.

Cells from the axial organ of the starfish Asterias rubens were fractionated into two populations, adherent and non-adherent to nylon wool. In both populations the ultrastructural study revealed the presence of cells resembling the lymphocytes of the vertebrates, as well as phagocytic, peroxidase positive cells. The lymphocyte-like cells in the non-adherent population (average diameter 4 mu) have a high nucleo-cytoplasmatic ratio and are morphologically similar to Th lymphocytes while the adherent cells (average diameter 5.

Possible role of sialic acid and endogenous neuraminidase in T-cell proliferation.

The proliferation of T cells in MLR with strains C57Bl/6 and DBA2, mouse spleen and lymph node cells was increased when the inhibitors of endogenous neuraminidase was added in the culture. This is in favor of participation of this enzyme and implicitly of terminal sialic acid in the proliferation of T-cells. Ths possibility that the suppressive activity of T-cells might have been abolished is discussed.

VIP inhibits histamine-induced ultrastructural changes related to acid secretion by parietal cells.

We have studied the in vitro effect of VIP and histamine on ultrastructure of the parietal cells in isolated guinea pig fundic glands. The morphological changes induced by histamine in the parietal cells can be compared to those observed after histamine stimulation in vivo or in vitro on gastric mucosa preparations. In contrast, VIP incubation did not produce the ultrastructural changes related to gastric acid secretion, in resting parietal cells.

The spatial organization of nucleolar DNA in phytohemagglutinin-stimulated lymphocytes of the guinea pig.

The ultrastructural changes in the spatial organization of nucleolar DNA in lymphocytes during phytohemagglutinin (PHA) stimulation was studied in guinea pigs by means of oxidized diaminobenzidine (DAB) at low pH as a differentially contrasting stain for nucleic acids and by the use of reconstruction of serial sections. The extended DNA filaments situated inside the fibrillar area originate from a large aggregation of heterochromatin, which is closely associated with the nucleolus, and from the perinucleolar shell of condensed chromatin. It is suggested that these two distinct regions of chromatin might be associated with different functions.

[Nucleolar lesions induced by ribonuclease in living cultured cells].

The nucleolar lesions provoked by the action of ribonuclease (RNase) on living chick embryo fibroblasts were studied by means of microcinematographic analysis and at the ultrastructural level using oxidized diaminobenzidine as a differentially contrasting stain for nucleic acids. This study has shown that the induction of nucleolar dispersion by RNase was only the beginning of a series of discrete steps. The following sequences are described: dispersion of the nucleolus into fragments, their reassembly, and the emission of spherules which appear of chromatin origin.

Destruction of Leishmania mexicana amazonensis amastigotes within macrophages in culture by phenazine methosulfate and other electron carriers.

Exposure of macrophages infected with Leishmania mexicana amazonensis to phenazine methosulfate (PMS) resulted in rapid damage and disappearance of the intracellular amastigotes without obvious ill effects to the host cells. The reduction of the percent infection was related to the concentration of PMS and to the duration of the pulse. Most Leishmania disappeared within 2 h of a 2-h pulse with 10 muM of the drug.

3H-glucosamine and 3H-fucose incorporation by murine peritoneal macrophages "non-divided" during differentiation in vitro.

Normal murine peritoneal macrophages were maintained in culture for 24 hours and 6 days. These cells continuously incorporated 3H-glucosamine and 3H-fucose in their membrane components. For both precursors culture ages, these components may be considered to undergo turnover according to a given rhythm with a 24 hours doubling time.

Nucleolar DNA organization in the interphase nuclei of mouse fibroblasts.

The organization of nucleolar DNA in interphase nuclei of somatic cells was studied at the ultrastructural level using oxidized DAB as a nucleic acid stain. Some finely filamentous networks of DNA-containing structures were observed within the nucleolar fibrillar component. They originated from the perinucleolar shell of condensed chromatin and from a chromatinic area with a honeycomb like structure.

Hairy cell leukemia: a clinical, immunological and ultrastructural study. New data for the origin of the hairy cell.

Seven patients presenting with the characteristic clinical and laboratory findings of HCL were investigated mainly in order to find the origin of the HC with histochemical, electron microscopic and immunologic techniques. The results we obtained are somewhat contradictory, as in the recent literature, if the HC's are to the considered as being exclusively of lymphocytic or monocytic origin. The data however indicate that HCL is not of one cell type but two.

Acute eosinophilic leukemia. An ultrastructural study.

Observations on a 32 year old male are described. Hematological examination demonstrated leukocytosis with circulating blastosis and dystrophic hypereosinophilia of the blood and bone marrow, with cells at various stages of maturation. Cytotoxic chemotherapy led to complete remission for 5 months followed by a terminal relapse.

Ultrastructural characteristics of developing eosinophil leukocytes in human bone marrow during acute leukemia: evidence for extracellular granule release from human eosinophils.

Developing eosinophils from the bone marrow of a patient with acute "eosinophilic" leukemia were characterized by electron microscopy. It was suggested that the first sequential step in granule formation occurred at the level of the endoplasmic reticulum without actual participation of the Golgi complex. Progressive densification of the former profiles, presumably mediated by Golgi vesicles, resulted in the formation of dense immature granules.

Studies on autoimmune encephalomyelitis in the guinea pig. II. An in vitro investigation on the nature, properties, and specificity of the serum-demyelinating factor.

Complement-dependent demyelinating activity of whole brain homogenate (WBH)-induced experimental allergic encephalomyelitis (EAE) sera was tested on long term tissue cultures of in vitro myelinated fetal guinea pig cerebellum. Complement-fixing (CF) auto-antibodies were shown to be the responsible agents, as demonstrated in experiments where all reagents belonged to the same species: guinea pigs of outbred (Hartley) and even of inbred (S2 or S13) strains. These antibodies were of the IgG2 class as shown by Sephadex G-200 and DEAE cellulose fractionation experiments.

[Ultrastructural demonstration of deoxyribonuclease-sensitive elements in fibrillar zones of the nucleoli of L 929 cell interphasic nuclei].

We have shown in our earlier paper (4) that a ribonuclease resistant filamentous network was associated with the fibrillar structures of the nucleolus of L 929 interphase nucleus. After desoxyribonuclease digestion and oxydised DAB opacification, the nucleolar fibrillar areas became heterogenous from an electron microscopical point of view. We have concluded that an important part of these fibrillar areas are composed of DNA and that the high electron dense fibrillar structures seen after desoxyribonuclease digestion, are the primary ribosomal gene product, just transcribed on the DNA matrix.

[Electron microscopic demonstration of links between DNA filaments and fibrillar areas of nucleolar RNA in interphase nuclei of L 929 cells].

Electronic opacification by DAB, following ribonuclease digestion, allowed us to observe a network of DNA filaments which appeared in close relation with both intranucleolar clumps of DNA on one hand, and with the nucleolar fibrillar RNA structure on the other hand. It is inferred that the ribosomal genes may be located on these filaments of DNA.

Effect of trimethylcolchicinic acid on the synthesis and excretion of proteoglycans in tissue culture.

The action of trimethylcolchicinic acid on the synthesis and excretion of proteoglycans has been studied on the L cell strain. The incorporation of precursors has been measured, and proteoglycans produced in the culture medium have been extracted and their concentration determined. The mucopolysaccharide components have been studied by electrophoresis.

Transfer of antigen from macrophages to lymphocytes. II. Immunological significance of the transfer of lipopolysaccharide.

The immunological significance of lipopolysaccharide (LPS) transfer from macrophage into lymphocytes was studied in an system in which the lymphocytes were incubated during 24–72 hours with macrophages which had previously ingested LPS (during 1 hour). Our results show that the immune response to LPS requires co-operation of lymphocytes with macrophages. After 24–72 hours of contact of the lymphocytes with macrophages containing ingested antigen, we observed within lymphocyte population a time dependent increase of the number of LPS-binding cells.