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Query: UMLS:C1275122 (TEM)
 21,810 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Antibody-dependent cellular cytotoxicity (ADCC), has been shown to be independent in vitro of thymus-derived lymphocytes, but the precise nature of the effector lymphocyte has not been fully clarified. To further study the identity of the ADCC effector cell type(s), peripheral blood leukocytes were purified by Ficoll-Hypaque density centrifugation and fractionated into surface immunoglobulin-positive [Ig(+)] and surface immunoglobulin-negative [Ig(-)] populations by chromatographic separation on Sephadex G-200 anti-human immunoglobulin columns. After column fractionations, the ADCC effector activity against antibody-coated autologous lymphocytes was predominantly and consistently found in the Ig(-) fraction. This latter population was then further fractionated, by rosetting techniques, into two subpopulations, The first was depleted by lymphocytes with surface receptors for sheep red blood cells [E(+)]and the second was depleted of lymphocytes with receptors for sheep red blood cell-antibody-complement [EAC-(+)]. Analysis of these populations showed that ADCC effector activity was predominantly a property of the Ig(-) lmyphocytes which are E(-) but EAC(+). These lymphocytes have been referred to as "null lymphocytes" and probably represent a subset of bone marrow-derived (B) cells. In addition, variable and low levels of ADCC activity were observed in some Ig(+) populations (B cells). Further purification of the null cell population by filtration over nylon wool columns to reduce the number of contaminating latex ingesting monocytes did not reduce ADCC effector activity. Isolated null cell ADCC effector activity was inhibited by either rabbit anti-human F(ab)2 or normal pooled rabbit gamma globulin, but not by rabbit F(ab)2 anti-human F)ab)2 or media. This supports the contention previously suggested in studies using unfractionated lymphocyte populations that the ADCC effector cell recognizes the Fc portion of the antibody molecule. The variable and low level of activity noted in the Ig(+) populations is unexplained but possibly due to a variable population of null cell-derived Ig(+) lymphocytes within the whole Ig(+) population. In conclusion, these experiments demonstrate that, in vitro, the major ADCC effector activity of circulating human peripheral blood lymphocytes resides in the Ig(-), E(-), EAC-(+) subpopulation termed "null cells." Since it has been noted that in certain disease states, such as immunodeficiency syndromes, autoimmune disorders, and neoplasms, the percentage of this population of lymphocytes in the peripheral blood is elevated, it is speculated that these cells, perhaps through their ADCC function, may play an important pathophysiologic role in these diseases.
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PMID:Human antibody-dependent cellular cytotoxicity. Isolation and identification of a subpopulation of peripheral blood lymphocytes which kill antibody-coated autologous target cells. 5 42

Subpopulations of human peripheral blood leukocytes were isolated by rosette formation and tested for functional activity. E -rosette-forming cells (E-RFC) and EAC-RFC were separated from non-resetting cells by sedimentation on Ficoll-Hypaque gradients. The efficiency of the method and the purity of the resulting subpopulations were high. E-RFC responded to PHA Con A, allogeneic leukocytes, and PPD, with higher levels of proliferative reactivity than the unseparated lymphocytes while E-RFC depleted, EAC-RFC, and null cells showed only low levels of reactivity. Reactivity to PWM and tetanus toxoid was also restricted to the E-RFC subpopulation, but was lower than that of unseparated cells. A staphylococcal antigen preparation triggered lymphoproliferative reactivity in the E-RFC, E-RFC depleted, EAC-RFC, and the null cell subpopulations. 51Cr release lymphocyte cytotoxicity against a human lymphoblast target cell line was found in the E-RFC and null cell fractions but was not observed with the EAC-RFC subpopulation.
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PMID:Functional activities of rosette separated human peripheral blood leukocytes. 12 61

Mononuclear cells (10--20 X 10(6)) obtained from human peripheral blood by a standard Ficoll-Hypaque technique were suspended in RPMI 1640 media at 4 degrees C containing 10% foetal calf serum and 7-5% dimethyl sulphoxide (DMSO). Two-millilitre aliquots were cooled at -1 degree C/min in a Cryoson BV-4 programmed freezing system to -30 degrees C, then -5 degrees C/min to -80 degrees C and stored in liquid nitrogen vapor. On the day of testing, cell suspensions were thawed rapidly in a 37 degree C water bath. DMSO was diluted slowly out of the sample and cells resuspended in fresh RPMI 1640. It was found that frozen stored human lymphocytes (FSHL) demonstrated all the characteristics of fresh unfrozen cells. These included their ability to form spontaneous rosettes with sheep erythrocytes ('E' rosettes) and sheep erythrocyte--antibody--complement rosettes ('EAC' rosettes). The presence of surface immunoglobulins and Fc receptors were shown by membrane immunofluorescence to be comparable. In addition, the results show that FSHL respond to mitogens, specific antigens; act as both stimulators and responders in the mixed lymphocyte culture reaction; and exhibit cell-mediated lymphocytotoxicity following in vitro sensitization, or against antibody-coated target cells.
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PMID:Immunological responsiveness of frozen-thawed human lymphocytes. 12 29

Mononuclear leucocytes were separated by Hypaque--Ficoll from 60 unselected primary colorectal carcinomas, and then fractionated by rosetting with sheep erythrocytes, either alone (E) or coated with antibody and complement (EAC). The E-rosetting cells, putative T lymphocytes, were cytotoxic in vitro to autologous tumour cells in 18 of the 60 cases, whilst the EAC-rosetting cells were unreactive. This intrinsic T-lymphocyte anti-tumour immunoreactivity was significantly associated with the presence of "cuffs" of small dark lymphocytes at the mesocolic or pararectal edge of the primary tumours, but there was no correlation with antitumour cytotoxic lymphocytes in the patient's blood at the time of operation.
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PMID:Immunoreactivity by intrinsic lymphoid cells in colorectal carcinoma. 31 8

Peripheral blood human T (TL) and B (BL) lymphocytes were separated by continuous Ficoll-Hypaque (FH) gradients. BL were found at the 1050 density interfase (70.5% EAC rosettes) with no TL (0% EAC rosettes); while at the 1068 density interfase there was an enrichment of TL (68% E rosettes) with very few BL (8.5% EAC rosettes).
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PMID:Enrichment in spontaneous and complement dependent rosette forming cell populations using Ficoll-Hypaque gradient centrifugation. 79 66

The effect, if any, of three different lymphocyte separation techniques on the composition and functional characteristics of the purified cell suspensions has been studied. Each separation technique was shown to yield a cell population with highly specific and reproducible characteristics. The Ficoll-Hypaque technique led to good lymphocyte yields but low yields of sheep erythrocyte-rosetting (E-rosetting) T cells, and the separated cell population responded least well to phytohemagglutinin. The glass sand filtration technique led to lowest overall yield of small lymphocytes and of EAC-rosetting cells. There was significantly lower total yield of E-rosetting T cell as well, but the separated lymphocyte suspension had excellent purity, had relatively high percentage of E-rosetting T cells, and they responded extremely well to phytohemagglutinin (PHA) and pokeweed mitogen (PWM). The Technicon separation involving magneticremoval of phagocytic cells by exposure to iron particles consistently led to large yields of small lymphocytes with good purity, the largest total harvests of E-rosetting T cells, as well as EAC-rosetting cells while the separated population had the highest percentage of E-rosetting cells and responded very well to PHA and PWM. These results show that lymphocyte losses during purification are not nonspecific and that the choice of the separation technique profoundly affects the characteristics of the purified lymphocyte population obtainable.
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PMID:Influence of separation techniques on the distribution and function of lymphocyte subpopulations. A comparison of three techniques. 96 32

The effects of cryopreservation (CP) on lymphocyte subpopulation distribution and functional activity in blastogenic and cytotoxicity assays were tested. Peripheral blood lymphocytes (PBL) from 12 healthy human donors were obtained by Ficoll-Hypaque separation. Half of each sample was tested fresh, while the other half was cryopreserved and then thawed and tested the same day. Each sample of CP-PBL was compared to fresh PBL from the same donor in simultaneous assays. Following CP there was a significant reduction in the percentage of E, EA gamma, and EA mu rosette-forming cells with a reciprocal increase in EAC rosette-forming cells. The blastogenic response to alloantigens was stable following CP while blastogenesis in unstimulated control cultures was significantly reduced. Mixed lymphocyte culture (MLC)-induced cell-mediated lympholysis (CML) was consistently and significantly diminished by CP. Cytotoxicity in 4 h chromium release NK (K562), ADCC, and LDCC assays was also significantly diminished by CP. In contrast, cytotoxicity was unaffected in an 18 h cytotoxicity assay against adherent cultured melanoma target cells.
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PMID:Lymphocyte surface markers and cytotoxicity following cryopreservation. 644 75

Separation of null cell fraction from the other cellular components of human peripheral blood obtained from normal healthy individuals was effected through the Ficoll-Hypaque density gradient centrifugation, carbonyl iron phagocytosis-magnet application, E-rosette forming and binding to 19S-EAC respectively. The null cells were used as effector cells in the cytotoxic assay. The spontaneous cell-mediated cytotoxicity assay was employed and the highly NK-sensitive K562 labelled with Na251 CrO4 were used as targets. The null cell fraction was divided into several portions to allow for normal control, diluent control and tests. The test portions were those exposed to the various antimalarial drugs employed. It was observed that the T cell, B cells and null cell fractions accounted for 72%, 18% and 10% of the total lymphocyte population respectively. The mean cytotoxicity generated by the natural killer subset was 63%. The antimalarial drugs/drug combination used were chloroquine, quinine, pyrimethamine and sulfadoxine/pyrimethamine combination. Concentrations used were their respective minimal inhibitory concentration (MIC) and corresponding 5 X MIC. The inhibitory effects on natural killer cell activity of these drugs were observed. The possible reasons for these observations are discussed.
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PMID:Effects of antimalarial drugs on human natural killer cell activity. 660 53

Lymphocytes separated from fresh heparinized blood or from blood stored 24 h at room temperature were tested for E rosettes, EAC Rosettes, and blastogenic response to phytohemagglutinin. Compared to lymphocytes from fresh blood, lymphocytes from 24 h stored blood contained a lower percentage of E rosette-positive cells, a higher percentage of E rosette-negative EAC rosette-negative null cells, and manifested a decreased blastogenic response to phytohemagglutinin. Fewer viable mononuclear cells were recovered by Ficoll-Hypaque separation from stored blood than from fresh blood. These findings suggest that storage-related changes may occur in T cells which cause a selective loss of such cells during Ficoll-Hypaque separation. A delay in processing of blood samples may therefore yield results of lymphocyte marker and functional assays which give the false impression of a decrease in T cells and an increase in null cells.
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PMID:Altered lymphocyte markers and blastogenic responses associated with 24 hour delay in processing of blood samples. 697 84

A 55-year-old female was admitted to Ogikubo Hospital for severe anemia and prolapse of a tumor from the anus, which had developed over 2 years. Rectal examination revealed a giant soft tumor. Endoscopic study revealed a lobulated giant tumor with a granular surface. Gastrografin-enema study showed a giant tumor, which was full of the rectum. Pathological examination showed a well differentiated carcinoma. No other prominent metastatic lesions were demonstrated. The transanal diagnostic resection of rectal cancer was performed in October 2010. This correct diagnosis showed both well differentiated adenocarcinoma and intramucosal carcinoma. We therefore recommend that a tumor of the lower rectum should undergo a diagnostic excision by means of either a local excision, ESD or TEM.
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PMID:[Treatment of early rectal carcinoma by transanal resection-a case report]. 2220 56


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