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Results for “Rosette Formation”

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At least 19 recordsLinked to original sources
PubMed1977

Spontaneous rosette formation and rosette inhibition assays in patients with squamous cell carcinoma of the head and neck.

Peripheral blood lymphocytes from patients with squamous cell carcinoma (SCC) of the head and neck were studied by spontaneous lymphocyte rosette and rosette inhibition (RI) assays prior to treatment. The patients were clinically staged and the results of the assays compared with the clinical stage of the disease. The percentage of T-lymphocytes as determined by the spontaneous lymphocyte rosette test was significantly lower (p less than .01) for the patient group when compared with a normal population. Patients with stage I and II disease did not differ significantly from controls. Individuals with stage III or IV disease, however, had significantly lower T-lymphocyte counts. The tumors were histologically graded as well, moderately well, or poorly differentiated SCC. Patients with poorly differentiated neoplasms had significantly lower T-cell counts. The RI assay (using horse anti-human thymocyte globulin to inhibit rosette formation) was abnormal in many of the patients but did not appear to be a more sensitive in vitro measure of cell mediated immunity in these patients. Performing both tests detected more patients with cellular immunologic incompetence than either one alone.

Adolescent↗
PubMed1976

Rosette formation between human lymphocytes and sheep erythrocytes. Inhibition of rosette formation by specific glycopeptides.

Rosette formation with unsensitized sheep erythrocytes is a characteristic of human thymus dependent lymphocytes. Release of glycopeptides from the sheep erythrocyte by trypsin reduces rosette formation. These tryptic glycopeptides inhibit rosette formation by untrypsinized sheep erythrocytes; this suggests that rosetting is mediated by erythrocyte surface glycopeptides. To investigate the molecular nature of this interaction, we examined the abilities of various model compounds to act as haptenic inhibitors of rosette formation. Inhibition is given by glycopeptides bearing oligosaccharide units rich in sialic acid, galactose, N-acetylglucosamine, and mannose linked to asparagine residues through glycosylamine bonds. Among compounds tested, fetuin glycopeptide is most effective, but human transferrin glycopeptide and human erythrocyte glycopeptide I also inhibit rosette formation. Other compounds including human erythrocyte glycopeptide II, human IgG glycopeptide, lacto-N-neotetraose, 3'- and 6'-sialyllactose show no significant inhibition. Neither sialic acid, galactose, manose, nor N-acetyl-glucosamine alone inhibits rosette formation. Stepwise degradation of fetuin glycopeptide established the galactose residues as important determinants of inhibitory activity. Fetuin glycopeptide blocks rosette formation when added to a suspension of human lymphocytes and sheep erythrocytes or when preincubated with human lymphocytes, but not when preincubated with sheep erythrocytes. Studies of the binding of [3H] fetuin glycopeptide to normal lymphocytes demonstrate 7.5 x 10(6) saturable binding sites per cell. No saturable binding of this compound to sheep erythrocyte membranes is observed. Compared to normals, lymphocytes from patients with chronic lymphatic leukemia demonstrate decreased fetuin glycopeptide binding with a mean of 0.9 x 10(6) sites per cell. This decreased binding correlates with the impaired ability of these cells to form rosettes. The data suggest that fetuin glycopeptide inhibits rosette formation by binding to the thymus-dependent cell where competition occurs with sheep erythrocytes for specific lymphocyte surface receptors.

Animals↗
PubMed1976

Modulation of human T lymphocyte rosette formation by autonomic agonists and cyclic nucleotides.

Early rosette formation by T lymphocytes appears to be modulated by cyclic nucleotides. Dibutyryl cyclic 3',5' adenosine monophosphate (cyclic AMP) 10(-2) M inhibited E rosette formation up to 83%, while 10(-6) M 8-bromo-cyclic guanosine monophosphate (cyclic GMP) increased rosette formation maximally to 67.4% with less pronounced effect at increased concentrations. T lymphocyte receptors for beta adrenergic, alpha adrenergic, and muscarinic cholinergic agonists appear to influence rosette formation. Isoproternol 10(-2) M induced 67.3% inhibition, while phenylephrine 10(-5) M and carbamylcholine 10(-4) M were associated with enhanced rosette formation of 67.2% and 57.8%, respectively. Selective blockade with propranolol, phentolamine, and atropine indicated the presence of separate receptor sites. The lack of effect of histamine at concentrations of 10(-3) M and above suggests the absence of specific recepotrs on peripheral human T lymphocytes.

Atropine↗
PubMed1978

The effect of varying SRBC/lymphocyte ratio on T cell rosette formation.

To determine the effect of varying the SRBC/lymphocyte ratio on rosette formation, rosettes were formed at SRBC/lymphocyte ratios ranging from 10 to 200. To assess the significance of the time of incubation, duplicate samples were mixed at various SRBC to lymphocyte ratios and the percentage of rosette-forming lymphocytes was determined immediately or after an 1-hour incubation at 4 degrees C. The results of five experiments revealed the highly statistically significant difference between the percentage of rosette-forming cells in tests performed with (higher number of RFC) and without (lower number of RFC) incubation, in all SRBC/lymphocyte ratios. On the other hand, ratio of SRBC to lymphocytes influenced significantly the results obtained in both types of tests, this effect was more pronounced in test performed with 1-hour incubation. Optimal SRBC/lymphocyte ratios for both tests were 100:1 (31% RFC without incubation and 53.4% of RFC after 1-hour incubation.

Animals↗
PubMed1977

Rosette formation assays in dogs: lack of specificity of E rosettes for T lymphocytes.

The present study examined the specificity of guinea pig erythrocyte (E) and erythrocyte-antibody-complement (EAC) rosette formation assays with suspensions of canine peripheral blood lymphocytes. Neutrophils, monocytes, and lymphocytes bound EAC but not erythrocyte-antibody (EA) controls. Similarly, all three cell types formed rosettes with guinea pig E. Adherence of guinea pig E to these cells was apparently mediated by natural cytophilic antibodies present in the serum used in the suspension medium. The nonspecificity of the guinea pig E-rosette formation assay with canine lymphocytes renders the technique unreliable for the identification of thymus-derived lymphocytes in dogs.

Animals↗
PubMed1978

In vitro radiosensitivity of human T and B lymphocytes evaluated using lymphocyte transformation tests and rosette formation tests.

The influence of irradiation upon human lymphocytes was studied using lymphocyte transformation tests and formation of E and HEAC rosettes. Irradiation was given in vitro using doses between 0 and 50,000 rad. It was shown that blast transformation after stimulation with T-cell stimulating agents (as PHA, PWM, Con.A and PPD) was suppressed by irradiation. The effect of irradiation upon T lymphocytes was also shown in different kinds of MLC experiments. Both the effect of irradiation upon rosetts formation and the influence of irradiation upon already formed rosettes were analyzed. The ability of lymphocytes to form E rosettes was affected after irradiation with 500 rad: there were fewer E rosettes with 3 SRBCs, decrease in total number of E rosettes and more null cells, with no depression of the number of HEAC rosettes formed. Already formed E and HEAC rosettes were totally unaffected of irradiation, and this radioresistance was also observed for 18-hour-old rosettes. The ability to form spontaneous E rosettes was decreased after irradiation of the lymphocytes with 100 rad; increasing doses did not cause further depression, and already formed spontaneous E rosettes were radioresistant. The mechanisms involved in E-rosette formation thus seem to be radiosensitive.

B-Lymphocytes↗
PubMed1977

A comparative study of procedures for sheep erythrocyte-human-T-lymphocyte rosette formation.

A comparative study of several published methods for sheep red blood cell-T-lymphocyte rosette formation was performed. Maximum SRBC-rosette formation occurred with AET treated SRBC in medium supplemented with 20% FCS or with untreated SRBC in 100% FCS. Prolongation of the 4 degrees C incubation period from 4 to 18 h enchanced rosette formation. Fluorescein diacetate staining significantly increased calculated percentage of rosette formation. Fluorescein diacetate staining significantly increased calculated percentage of rosette-forming lyphocytes by allowing accurate indentification of the central lymphocytes in morulas.

Animals↗
PubMed1978

Lack of effect of halothane on E, EA, and EAC rosette formation and cyclic AMP level of human lymphocytes.

The effect of halothane on rosette formation and cyclic adenosine monophosphate (cyclic AMP) level of human lymphocytes was investigated. A 4- or 24-hour incubation with 2% halothane had no significant effect on "early" or "late" E, EA and EAC rosette formation or intracellular cyclic AMP levels of human lymphocytes whereas cytochalasin B, which affects microfilament action, reversibly inhibited both E and EA but not EAC rosette formation. It is suggested that halothane in clinical concentrations neither disturbs the function of microfilaments, essential for E and EA rosette formation, nor affects the metabolism of cyclic AMP in unstimulated human lymphocytes.

Cells, Cultured↗
PubMed1977

Restoration by levamisole of histamine-inhibited E rosette formation of T lymphocytes of patients with allergies.

Histamine significantly inhibited the E rosette formation of T lymphocytes of patients with allergies in vitro, but had no effect on the E rosette formation of T lymphocytes of healthy subjects. This inhibitory effect was obtained by concentrations of 3.10(-4) down to 3.10(-7) M histamine and depended on the time of incubation. Levamisole an antianergic chemotherapeutic agent, could restore the histamine-inhibited E rosette formation. It is postulated that patients with allergies possess a subpopulation of T lymphocytes bearing histamine receptors and that the inhibitory effect of histamine on E rosette formation is medicated by intracellular cAMP.

Adolescent↗
PubMed1979

Inhibition of rosette formation of IgE-bearing rat mast cells by disodium chromoglycate.

The interaction of reaginic antibody with specific antigen was studied by the rosette formation of peritoneal rat mast cells. The mast cells were obtained from actively sensitized rats or were passively sensitized in vitro. Rosette formation was of a higher degree with mast cells of actively sensitized rats; in this case 58% of the cells showed a strong rosette-forming effect (blinding more than 5 SRBC). No rosette formation was detected in 18% of the cells. With passively sensitized rat mast cells, rosette formation was 45% and 22%, respectively. Rosette formation of both actively and passively sensitized mast cells could be inhibited by disodium chromoglycate (DSCG); the inhibitory effect of 20 micrograms and 200 micrograms of the drug was the same, and neither dose caused a full inhibition. It is suggested that the linkage of specific antigen to the surface of sensitized mast cells can be inhibited by DSCG in vivo.

Animals↗
PubMed1977

Human lymphocyte subpopulations: rosette formation with sheep, human and horse red blood cells.

Rosette formation between human lymphocytes and horse red blood cells could be promoted by a low pH medium, overnight incubation and a temperature of 4 degrees C. The percent of sheep, horse and human rosette-forming cells in the peripheral blood were 71.7 +/- 1.8, 30.5 +/- 2.8 and 28.3 +/- 3.4 respectively. However, their percentages in thymuses were 97.1 +/- 1.1, 91.4 +/- 2.4 and 89.0 +/- 3.4. Using preparations of isolated subpopulations, it was observed that the horse and human red cell rosette-forming cells were probably also "early" sheep red cell rosette-forming cells. Rosette formation with all three types of red blood cells were inhibited by a preparation of Fetuin-glycopeptide.

Animals↗
PubMedDate not supplied

[Effect of the serum of patients with cholestasis on lymphocyte E rosette formation].

Sera from cholestatic patients have been found to interfere with lymphocyte rosette formation (E rosettes). Lymphocytes from patients with cholestasis showed a lower percentage (42.36%) of cells binding sheep red blood cells in comparison with a control group (62%). In the presence of cholestatic serum the number of E rosettes formed by lymphocytes from normal subjects declined to 44.16%. This behaviour, however, can reverse, since lymphocytes from cholestatic patients previously incubated with normal serum, showed a nearly normal capability of forming E rosettes (57.90%). Therefore, it is conceivable that among the several factors which are present in sera from patients with either chronic or acute hepatitis and which are able to interfere with T-lymphocyte function, there may be included also the factor which is present in sera from cholestatic patients. The possible role of bile salts and hyperlipoproteinaemia present in those patients requires further investigation.

Cholestasis↗
PubMed1979

Inhibition of complement-dependent rosette formation after lymphocyte incubation with fatty acids.

Overnight incubation of lymphocytes with certain fatty acids bound to albumin has previously been shown to modify the fatty acid composition of cellular phosphoglycerides without impairing viability, and also to inhibit mitogen and antigen-induced lymphocyte transformation. In the present study, incubation of human lymphocytes with palmitic acid or with linoleic acid impaired their capacity to form complement-dependent rosettes but had no effect on either spontaneous rosette formation with sheep erythrocytes or Fc(gamma)-dependent rosette formation. With mouse lymphocytes, complement-dependent rosette formation was suppressed only following incubation with linoleic acid and there was no effect on Fc(gamma)-dependent rosette formation. Although the mechanism of these effects remains to be elucidated the results suggest that control of membrane lipid composition may modify the important in vivo immunological functions which involve complement receptors.

Animals↗
PubMed1979

Inhibition of human lymphocyte E-rosette formation by oxygenated sterols.

25-Hydroxycholesterol, 20 alpha-hydroxycholesterol, 7 alpha-hydroxycholesterol, and 5 alpha-hydroxy-6-ketocholestanol, when added to cultures of human lymphocytes in lipoprotein-depleted medium (LPDM) at a concentration of 2.5 x 10(-6) M, inhibit E-rosette formation with sheep red blood cells. 20 alpha-Hydroxycholesterol, 7 alpha-hydroxycholesterol, and 5 alpha-hydroxy-6-ketocholestanol are more potent inhibitors than 25-hydroxycholesterol. The inhibitory effect of 5 alpha-hydroxy-6-ketocholestanol on E-rosette formation appears after 15 min of exposure; with the other three compounds, an exposure time of 18 hr is necessary. The inhibitory effect of E-rosette formation can be abolished by addition of free cholesterol, low-density lipoprotein, or high-density lipoprotein to the LPDM or by incubation of the cells in normal AB serum, but not by the addition of mevalonic acid to the LPDM. These observations suggest that the capacity of oxygenated sterol compounds (OSC) to inhibit E-rosette formation is independent of their inhibitory effect on sterol synthesis. It is possible that OSC inhibit E-rosette formation as a consequence of their insertion into the lymphocyte membrane as cholesterol analogues.

Cell Survival↗
PubMed1976

Enhancement of early human E rosette formation by cholinergic stimuli.

The effects of the cholinergic stimuli carbamylcholine (carbachol) and dibutyrl cyclic guanosine monophosphate (DBCGMP) were determined on both 'early' and 'total' E rosette formation. Ficoll-Hypaque-separated lymphocytes were preincubated with either carbachol or DBCGMP over a 10(-3) M to 10(-13) M dose range. Both agents significantly enhanced 'early', but not 'total' E rosette formation. Peak enhancement above control values occurred at 10(-7) M (72%) and 10(-9) M (69%) for carbachol and 10(-5) M (70%) and 10(-7) M (70%) for DBCGMP. Kinetic studies showed a rapid onset of enhancement (2.5 min) for carbachol, whereas DBCGMP required 15 min for significant enhancement to occur. The muscurinic nature of carbachol enhancement of E rosettes was demonstrated. Atropine at 10(-7) M completely abolished the carbachol effect while showing little inhibition of the DBCGMP effect on rosette formation. These studies indicate that the cholinergic stimuli carbachl and DBCGMP significantly enhance the 'early' E rosette former in man. Human T lymphocytes appear to have functional cholinergic receptors that can be blocked by the muscurinic antagonist atropine. The role of the cyclic nucleotides and their stimulants on the immune system is incompletely understood, but it would appear that they are extremely important in the differentiation and function of the T lymphocyte. E rosette formation may be a useful model in man for studying the effects of the cyclic nucleotides on the human T lymphocyte.

Butyrates↗
PubMed1976

Prognostic value of mouse red cell rosette formation in chronic lymphocytic leukaemia.

Mouse red cell (MRC) rosette formation was studied in 20 malignant haemopathies. Only cells from chronic lymphocytic leukaemia (CLL) and hairy cell leukaemia (HCL) formed MRC rosettes with a high frequency. However, cells from 2 cases of CLL could not be demonstrated to form MRC rosettes, although they were undoubtedly found to be of B origin. These 2 cases presented as typical CLL, but they were observed to transform into a sarcomatous type after 5-6 months of evolution, suggesting that the study of MRC rosette formation might be of prognostic value in CLL.

Adolescent↗
PubMed1977

["E" rosette formation in "active" T lymphocytes: phenomenon modulated by intracellular level of cyclic AMP and GMP (author's transl)].

The rosette formation envolving the binding of sheep red blood cells (SRBC) with active T lymphocytes was activated when the lymphocytes were incubated with levamisole, acetylcholine or carbamylcholine. Similar activation was seen when to the incubation medium was added substances of glucose metabolism (lactate, fumarate or succinate) or triphosphate de adenosina--ATP. The lymphocytes incubation with aminophyline, isoproterenol or 2-4-dinitrofenol--DNP--inhibited the rosette formation. The inhibition promoted by aminophyline was reversed by levamisole, acetylcholine or carbamylcholine, but not when lactate or ATP was used. When the rosette formation inhibition was caused by DNP, the reversion was only possible by ATP and no affect occurred if guanil cyclase activators were added to the incubation medium.

Acetylcholine↗
PubMed1977

Rosette formation by sensitized human red cells- effects of source of peripheral leukocyte monolayers.

Employing standardized IgG-coated 51Cr-labelled human red blood cells (RBC), variation in rosette formation among monolayers obtained from 10 healthy donors was defined, as well as variation among 24 sequential monolayers obtained from one healthy donor and 8 sequential monolayers from a second healthy donor over a 4-month period. Rosette formation, expressed as eluate cpm per plate, average 220 (range 35-472) for the 10 donors; 24 determinations on one donor average 201 (range 59-420), 8 determinations on the second donor averaged 244 (range 69-395). Striking increases in rosette formation were observed employing monolayers from 4 of 4 normal subjects during the course of viral infections, with peak values exceeding 5, 8, 13 and 14 X the normal mean. Elevations were also observed with monolayers prepared from blood of selected patients with hematologic disorders; a remarkable value 168 X the normal mean was repeatedly obtained for a patient with myeloid metaplasia whose monolayer consisted almost exclusively of mature granulocytic rosette-forming cells. The results emphasize the influence of monolayer donor variables on rosette formation.

Acute Disease↗