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Biomedical subjects

R Ciorbaru

Publications and source records attributed to R Ciorbaru.

At least 19 recordsLinked to original sources
PubMed1978

Human B cell differentiation. I. Immunoglobulin synthesis induced by Nocardia mitogen.

Nocardia water-soluble mitogen (NWSM) is a mitogen which activates human B lymphocytes even in the absence of T cells. Tonsil and peripheral blood lymphocytes cultured in the presence of NWSM gave rise to large numbers of cells containing cytoplasmic immunoglobulins of IgM, IgA or IgG classes. The number of plasma cells appeared to be elevated as early as day 3 of culture and peaked on day 5 or 7. The IgM response preceded the development of cells containing other Ig classes, and was found to remain predominant on days 5 and 7. A similar number of plasma cells were generated in T-deprived suspensions; however, a quantitative regulation by T cells cannot yet be excluded. The response to pokeweed mitogen appeared to be similar, except that it was often less intense and not observed in the absence of T cells. Very few or no IgD-containing cells were found to be differentiated with both mitogens.

B-Lymphocytes↗
PubMed1977

Nocardia water-soluble mitogen and lipopolysaccharide. Comparative study of two adjuvants and B-cell mitogens in mice.

The activity of Nocardia water-soluble mitogen (NWSM) and LPS were compared in several experimental systems, since both compounds are B-cell mitogens and polyclonal activators in vitro. The results reported here demonstrated that NWSM like LPS also has a strong adjuvant activity in vivo if administered in saline with a strong antigen (heterologous red blood cells) or even with a weak immunogen such as theta alloantigen. However, in contrast to LPS, NWSM administered to mice failed to induce in vivo proliferation of lymphocytes, polyclonal activation and PFC against syngeneic bromelain-treated erythrocytes and thymocytes. It is possible therefore, that different mechanisms may be responsible for adjuvant activity of NWSM and LPS.

Adjuvants, Immunologic↗
PubMed1976

Presence and subcellular localization of two distinct mitogenic fractions in the cells of Nocardia rubra and Nocardia opaca: preparation of soluble mitogenic peptidoglycan fractions.

Fractionation of cells of Nocardia rubra and Nocardia opaca led to the separation of the cell wall and a "cytoplasmic" fraction. Both fractions were mitogenic for the splenocytes of AKR and nude mice and of rabbits. The peptidoglycan was the active part of the cell wall fraction. The products solubilized by the action of Streptomyces albus G peptidases on the peptidoglycan of N. rubra were mitogenic, but the products solubilized by lysoyme were not. Tentative structures are proposed for these fractions. The most active part of the cytoplasmic fractions could be sedimented by centrifugation and seemed to be related to the cytoplasmic membrane.

Animals↗
PubMed1976

A human T-independent B lymphocyte mitogen extracted from Nocardia opaca.

Nocardia water soluble mitogen (NWSM), a mitogen specific for mouse and rabbit B cells, activates blood, spleen, and tonsil lymphocytes from all the humans tested. Evidence is presented that it acts selectively on human B lymphocytes. B-enriched cells were recovered from anti-Ig-coated Sephadex columns or after elimination of E rosette-forming cells: they were able to incorporate tritiated thymidine when they were cultivated in the presence of NWSM whereas they were not activated by PWM. Conversely T-enriched suspensions did not respond to NWSM although they were able to be stimulated by PHA and PWM. Moreover, the response to NWSM remained unchanged after T cells had been killed by anti-HTLA serum and complement and disappeared after B cells had been killed by anti-HBLMA serum. After stimulation by NWSM, the number of direct plaque-forming cells to HRBC, LPS, and TNP was significantly increased, showing a polyclonal activation of human B lymphocytes. Since no evidence of T cell help for B cell activation has been found, NWSM thus appears to be a T-independent human B lymphocyte mitogen.

B-Lymphocytes↗
PubMed1975

Isolation of mitogenic and adjuvant active fractions from various species of Nocardiae.

Delipidated lysozyme digests of Nocardia opaca, N. corallina, and N. rubra have been fractionated by Sephadex filtration. The mitogenic and adjuvant activities of the fractions thus obtained have been investigated. All fractions are mitogenic except the last fraction of N.rubra, but the N. opaca products induce a stronger stimulation of mouse spleen lymphocytes than the corresponding fractions of the two other species. The activity of the first Sephadex fractions of each strain has been compared to other mitogens (concanavalin A, lipopolysaccharide). All fractions are adjuvant, although one of them, the last Sephadex fraction of N. rubra, does not contain peptidoglycan; its activity must thus be attributed to another kind of molecule. Fractionation of the first Sephadex fraction of N. opaca by centrifugation in glacial acetic acid led to a separation of adjuvant and mitogenic activities.

Adjuvants, Immunologic↗
PubMed1975

Blast transformation of rabbit B-derived lymphocytes by a mitogen extracted from Nocardia.

Nocardia water soluble mitogen (NWSM) is known to stimulate mouse and rabbit lymphoid cells and to act selectively on murine B-derived lymphocytes. In this paper, evidence is presented that NWSM is also a mitogen for rabbit bursal equivalent cells and does not bring about blast transformation of thymus-derived rabbit cells. Pretreatment of rabbit spleen lymphocytes with antibody directed against rabbit thymus lymphocyte antigen (anti RTLA serum) and with complement did not affect the strong increase of thymidine incorporation which follows stimulation with NWSM. The mitogen-induced polyclonal activation of antibody-forming cells and resulted in the presence of 30% of cells with the ultrastructural characteristics of plasmocytes. These observations led to the conclusion that NWSM is a mitogen for a B-derived lymphocyte of the rabbit.

Animals↗
PubMed1975

Peptidoglycan adjuvants: minimal structure required for activity.

The chemical structure of the adjuvant active fraction of mycobacterial cell walls has been investigated. It had been shown previously that soluble peptidoglycan fragments obtained from cell walls of Mycobacteria by lysozyme digestion or by other treatments act as adjuvants for increasing both humoral and cellular immunity. We then found that even the monomer subunit of the peptidoglycan of Mycobacteria (i.e. a disaccharide-tetrapeptide) is adjuvant active; then, similar compounds from other strains of bacteria were tested; the monomeric subunits of meso-diaminopimelic acid as well as L-lysine containing peptidoglycans were found to be adjuvant active. The smallest active compound studied so far is N-acetyl-muramyl-L-alanyl-D-isoglutamine synthesized for us by SINAY et al. (1975).

Adjuvants, Immunologic↗
PubMed1973

Preparation and biological properties of water-soluble adjuvant fractions from delipidated cells of Mycobacterium smegmatis and Nocardia opaca.

Digestion by lysozyme of delipidated cells of Mycobacterium smegmatis liberates a water-soluble immunoadjuvant fraction which is chemically very similar to the water-soluble adjuvant (WSA) obtained previously from purified cell walls, but which contains somewhat more non-peptidoglycan amino acids. The yield of peptidoglycan-arabinogalactan complex is about 10 times greater starting from whole cells than from cell walls. The main biological properties of this "neo-WSA" are described: it increases circulating antibodies to ovalbumin in guinea pigs, it does not produce polyarthritis in rats or induce hypersensitivity to tuberculin, it does not increase susceptibility to histamine or hyperreactivity to endotoxin, and does not produce spleen and liver hypertrophy. Analogous immunostimulant fractions have also been obtained from delipidated cells of Nocardia opaca by lysozyme treatment.

Adjuvants, Immunologic↗
PubMed1972

Isolation and properties of a macromolecular, water-soluble, immuno-adjuvant fraction from the cell wall of Mycobacterium smegmatis.

Trypsin- and chymotrypsin-treated delipidated cell walls of Mycobacterium smegmatis were digested overnight with lysozyme. The water-soluble products thus obtained were filtered on a column of Sephadex G-50; the first peak, excluded from the column, has immunological adjuvant activity. The material of the excluded peak is obtained after lyophilization as a snow-white, fluffy material, soluble in water and insoluble in organic solvents. It behaves as a slightly polydisperse macromolecule in an ultracentrifuge, with an approximate molecular weight of 20,000. All the constituents of this material are typical bacterial cell-wall constituents; thus, the water-soluble adjuvant is considered to be an "oligomer" of the cell wall. When added to Freund's incomplete adjuvant with an antigen (e.g., ovalbumin) and injected into hind-foot pads of guinea pigs, this water-soluble adjuvant increases the amount of precipitating antibodies and induces hypersensitivity to ovalbumin and the biosynthesis of gamma(2)-type precipitating antibodies. The water-soluble material has a stronger adjuvant activity than equal amounts of whole bacteria, cell walls, or wax D, and seems to be the first well-defined, water-soluble, adjuvant-active fraction isolated from Mycobacteria.

Adjuvants, Immunologic↗