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D Sulitzeanu

Publications and source records attributed to D Sulitzeanu.

16 recordsLinked to original sources
PubMed1992

Degenerative changes in the A375 melanoma line induced by transforming growth factor beta 1.

A375 human melanoma cell cultures grown in the presence of TGF beta contained greatly reduced cell numbers and exhibited drastic alterations in cell morphology compared to the control cultures. Preincubation of the cells with the cytokine for only 18 h was sufficient to induce these changes irreversibly. Examination of TGF beta-treated cells in the electron microscope revealed large numbers of lipid-filled vacuoles in the cytoplasm, greatly contracted nuclei and some loss of the otherwise abundant microvilli. Thus TGF beta may have a direct toxic effect on the A375 melanoma cells.

Cell Count↗
PubMed1992

Cloning and characterization of the latent membrane protein (LMP) of a specific Epstein-Barr virus variant derived from the nasopharyngeal carcinoma in the Taiwanese population.

A DNA fragment containing Epstein-Barr virus (EBV) terminal fragment sequence was obtained from a genomic library of nasopharyngeal carcinoma (NPC). One of the clones (clone 1510) contained the gene encoding latent membrane protein (LMP). Sequence analysis revealed that this gene had 95% homology with the LMP sequence of the B95-8 strain. Among the sequence variations, there was a change from G to T at nucleotide position 169,426, resulting in the loss of an XhoI site in exon 1 of the LMP gene. A pair of primers bracketing the XhoI site were designed to synthesize the EBV DNA fragment from nucleotides 169,081-169,577 by using the polymerase chain reaction (PCR) method. The PCR products were then subject to XhoI digestion and to DNA sequencing analysis. This restriction enzyme site polymorphism along with the sequence variations were also observed in 50 biopsy tissues as well as in the throat washings of 6 out of 20 healthy individuals that we examined, indicating that the EBV strain predominantly existing in these biopsy tissues was different from strains of B95-8, Jijoye or nude mouse passaged cells (C15) with an African origin, but closely resembled other nude mouse passaged CAO cells which were originally derived from China. Balb/c 3T3 cells carrying this NPC-LMP gene showed a transformed cell morphology and were tumorigenic in nude mice. The relationship between this unique type of EBV and NPC has yet to be established.

3T3 Cells↗
PubMed1979

A technique for the purification of immune complexes using rheumatoid factor.

A method for the purification of immune complexes (IC) from human serum is described, using as a model complexes of tetanus toxoid with human antitoxoid antibodies (TAT). The technique is based on the ability of IC to bind to tubes coated with rheumatoid factor (RF). Small amounts of TAT IC were added to human serum and the mixtures were rotated overnight in tubes coated with RF. The tubes were then washed and the bound material was eluted with sodium dodecyl sulphate and iodinated with 125I. Analysis of the labeled preparation by electrophoresis in polyacrylamide gels revealed the presence of the toxoid component. The technique should be useful in isolating small amounts of IC for analytical purposes.

Antibodies↗
PubMed1979

Single and double stranded DNA binding lymphocytes in the peripheral blood of patients with systemic lupus erythematosus and normal controls.

Specific double (D-DNA) and single stranded (S-DNA) deoxyribonucleic acid binding cells were demonstrated in the peripheral blood lymphocytes of patients with systemic lupus erythematosus (SLE) by rosette formation with antigen coated red blood cells. The proportion of DNA binding cells in the peripheral blood of patients with SLE was significantly higher than that found in a random population of healthy individuals. Significant numbers of D-and S-DNA binding lymphocytes were found in patients with active disease even when anti-DNA of fluorescent antinuclear antibodies disappeared. The specificity of the DNA binding cells was confirmed by inhibition experiments with D-or S-DNA. Spleen lymphocytes were also examined on one occasion and were found to contain a much higher level of DNA binding lymphocytes than the peripheral blood lymphocytes.

Antibodies, Antinuclear↗
PubMed1976

Relation of antigen-binding cells to immunological memory.

Priming of mice with a conjugate of HSA with sheep red cells induced a high level of memory to HSA, with very little antibody production ("pure priming"). HSA specific antigen binding cells in the spleens of the primed mice were assayed by means of a rosette technique, using HSA conjugated to donkey red cells. Rosette formation was almost completely inhibited by soluble HSA, thus confirming that the RFC were specific for this antigen. Spleens of primed mice contained up to 0.6% RFC, as compared to 0.08% HSA specific RFC in the spleens of non immunized animals. Suspensions enriched in rosettes (containing up to 16% RFC) were prepared by centrifugation on BSA density gradients. Adoptive transfer experiments showed that the rosette rich fraction contained all the memory cells. A marginal level of memory could be transferred to irradiated recipients with 3000 rosettes. A comparable degree of responsiveness to HSA could also be transferred with 70,000 RFC enriched from spleens of non immunized mice, but only when injected together with primed, RFC depleted spleen cells. Kinetic studies showed that the level of memory correlated well with the number of RFC up to two months after priming. The number of RFC decreased at later time intervals (though remaining higher than in controls at all times), without a corresponding decrease in the level of memory. A change in the quality of the memory cell with time is postulated.

Animals↗
PubMed1976

Isolation from patients with breast cancer of antibodies specific for antigens associated with breast cancer and other malignant diseases.

Antibodies were specifically purified, with the use of pleural fluid antigens entrapped in a polyacrylamide gel as immunoadsorbent, from a pool of sera from patients with breast cancer and from the pleural effusion of an individual patient. The purified antibodies were radioiodinated and tested for capacity to bind to the pleural fluid adsorbent. Binding of the radiolabeled antibodies was inhibited by many of the sera from women with breast cancer to a much greater extent than by sera of healthy women. With purified antibodies originating from the serum, 52% of the breast cancer sera and 16% of sera from patients with other malignancies were more inhibitory than were 95% of the sera of healthy women. In the tests with antibodies eluted from pleural fluid, 24% of the breast cancer sera and 25% of the sera from patients with other neoplastic diseases were more inhibitory than were 95% of the normal sera. We concluded that sera of patients with breast cancer may contain antibodies against antigens associated with breast cancer as well as additional antibodies against antigens that are also found in patients with other neoplastic diseases or in normal individuals. Individual breast cancer sera may inhibit binding of the labeled antibodies against breast cancer owing to their content of antibodies, antigen(s), or both.

Antibodies, Neoplasm↗
PubMed1976

Coexistence in human sera of a cell (membrane?) ANTIGEN AND Of autoantibodies directed against it.

Antibodies purified from sera of patients with Burkitt's lymphoma by absorption onto and elution from cultured lymphoblastoid cells, were labeled with 125I and repurified by repeating the absorption-elution procedure. The doubly purified antibodies could bound with a high degree of efficiency to immunoadsorbents prepared by entrapping in polyacrylamide gel normal human serum or exudate fluids from patients with ovarian or breast cancer. Binding was specific, as it could be inhibited by high dilutions of human sera but not by animal sera. Globulin fractions of human sera were strongly inhibitory. Their capacity to inhibit was lost after treatment with rabbit anti-human IgG serum, indicating that at least part of the inhibition could be ascribed to antibodies. Some inhibitory activity was also found, however, in the "albumin" fractions of sera, suggesting that an antigen was also involved. It appears, therefore, that practically all human sera contain antibodies reacting with an antigen(s) which is present on human cells and is also circulating freely in serum and other body fluids. Sera of patients with Burkitt's lymphoma contained, on the average higher concentrations of these antibodies, as compared to sera of individuals not suffering from this disease. This antigen is thought to be associated with the cell membrane and has been identified in cells of widely differing origin.

Antibody Specificity↗
PubMed1975

A radioactive antibody binding-inhibition assay, for the detection of cell-membrane related antigens in body fluids.

Antisera raised in rabbits against glutaraldehyde-fixed human breast cancer cells contain antibodies to human cell membrane components, as determined by immunofluorescence. Adsorption of such antisera onto polymerized human serum, followed by acid elution, yields purified antibodies reacting with human cell surface antigens, indicating that membrane related antigens are present in the serum. The purified antibodies were radioiodinated and shown to bind to an immunoadsorbent prepared by entrapping in a polyacrylamide gel pleural exudate of breast cancer patients. The specificity of the binding was confirmed by inhibition experiments. Data are presented demonstrating that at least some of the antibodies reacting in this radioimmunoassay are directed against antigens related to cell surface components.

Adsorption↗
PubMed1975

Subpopulations of mouse spleen lymphocytes. II. Immunological reactivity of spleen cells fractionated on BSA density gradients.

We found in previous experiments that fractionation of non-immune mouse spleen cells on bovine serum albumin density gradients yields two subpopulations of T cells, one of high, the other of low density. Both subopopulations could be stimulated in corporate thymidine by the T cell-specific mitogen concanavalin A (con A). In the present investigation, spleen cells of mice immunized to sheep red cells (SRC) were similarly fractionated and the fractions recovered were assayed for: (a) reactivity to con A; (B) REACTIVITY TO SRC and (c) capacity to function as helper cells when stimulated with the homologous (SRC) or with a heterologous (donkey red cells) (DRC) antigen. Two subpopulations of cells reacting to con A were found in the spleens of the primed mice, corresponding to the subpopulations found in the non-immune mice. Both subpopulations contained cells responding to SRC (as measured by thymidine incorporation) and cells endowed with helper activity. The two subpopulations appeared to differ, however, in their specificity: while the denser cells could only exert their helper effect when stimulated by the specific antigen, the light cells could be effectively stimulated by both the specific (SRC) and the nonspecific (DRC) antigen.

Animals↗
PubMed1975

Enrichment of memory cells carrying receptors for a protein antigen (HSA). II. Improved enrichment technique, using BSA density gradient separation.

Mice primed to human serum albumin (HSA) by means of an HSA--sheep red cell conjugate, developed a high level of memory to HSA, with little concomitant antibody production ('pure priming'). The proportion of HSA-specific antigen-binding cells was determined in the spleens of the primed mice by means of a rosette technique, using an HSA-donkey red cell conjugate. The specificity of the rosette-forming cells (RFC) was confirmed by the ability of soluble HSA to inhibit rosette formation. Highly enriched rosette suspensions (up to 40-fold enrichment) were prepared by bovine serum albumin density gradient centrifugation. The enriched suspensions could transfer adoptively memory to HSA, whereas the rosette-depleted fractions were totally inactive. It was thus confirmed that memory cells are included in the antigen-binding cells. A detectable level of memory could be transferred with 3000 rosettes. RFC similarly isolated from spleens of non-primed mice could also transfer a low level of responsiveness to HSA, but only when large numbers (70,000) were injected, together with primed, RFC-depleted spleen cells.

Animals↗
PubMed1975

Subpopulations of mouse spleen lymphocytes. III. Cellular interactions in the response to concanavalin A.

The profile of response to concanavalin A (con A) of purified mouse T cells was found to differ appreciably from that of non-fractionated spleen cells, in agreement with results previously published by other investigators. Experiments designed to elucidate the reasons underlying these differences have revealed that the response of the spleen cells to con A is determined by a complex interplay between several cell types. (a) B cells contribute to the overall incorporation of thymidine in the presence of con A-stimulated T cells. However, the B cells participate in the response only if the T cells are dividing. (b) A population of 'adherent cells' is present in the spleen, which enhances the stimulation of the spleen cells by low doses of con A but suppresses the response to high doses of mitogen. These adherent cells include most likely the conventional macrophages, but probably also a population of 'suppressor T cells'. (c) Such 'suppressor T' cells can be readily detected among the peritoneal exudate cells. Addition of the exudate cells to cultures of purified T cells enhances the response to low doses of con A. This effect can be further increased by treating the peritoneal cells with a cell T-specific antiserum and complement, i.e. by eliminating the T cells.

Animals↗