Binding characteristics of Fc receptors for IgG on human peripheral blood T gamma lymphocytes and "L" lymphocytes: a technical report

Effects of endometrial IgG on PHA-induced T cell mitogenesis

To clarify the characterization and immunologic mechanisms of endometrial extract as a suppressive factor in tissues of the implantation site, the effects of endometrial extract and IgG on mitogen-stimulated cultures of lymphocytes from human peripheral blood were investigated. The inhibitory activity of endometrial extracts was observed to be augmented markedly in the secretory phase of the menstrual cycle as compared to the proliferative phase. Secretory endometrial extract, at a concentration of 0.6 mg protein/ml, caused 50% suppression of PHA-induced lymphocyte blastogenesis (PHA-BL). Column fractionation of endometrial extract on a Sephadex G-200 column showed a profile with three peak fractions and demonstrated that the 2nd peak fraction was mainly responsible for the suppression of PHA-BL. The 2nd peak fraction was shown to contain IgG by the method of immunodiffusion with anti-human IgG. The 2nd peak fraction from which IgG was removed with affinity chromatography caused significant depression of PHA-BL. Furthermore, the Fc fraction of IgG showed marked suppression compared to the F(ab')2 fraction. From these results, we suggest the possibility of an endogenous substance containing IgG as a suppressive factor which is implicated in the suppression of T cell function. The Fc fragment seemed to be the major fraction possessing such suppressive activity.

Fc gamma-receptor-bearing, non-B lymphocytes in human peripheral blood: cytophilic immunoglobulin binds almost exclusively to large granular lymphocytes

Cytophilic IgG (CYT-Ig) has previously been reported to bind to both the "TG" (E+, Fc gamma R+) and "L" (E-, Fc gamma R+) subsets of non-B lymphocytes in human peripheral blood. Present investigations show that IgG-binding cells, as detected by a sensitive antiglobulin rosetting reaction, are contained almost entirely within the large granular lymphocyte (LGL) subpopulation, and that fewer than 5% of other non-B lymphocytes acquire IgG from serum. Cell membrane-bound IgG sterically blocks the reaction of LGL with sheep red blood cells and therefore influences the proportions of these cells characterized as TG (E+) or L (E-) lymphocytes. Although the majority of TG lymphocytes are LGL, a further subpopulation of E+, Fc gamma R+ cells are detectable under particular test conditions. Unlike LGL, these lymphocytes do not react with rabbit IgG-coated ox RBC (EAG) in saline, but will form EAG rosettes when the reaction is enhanced in the presence of Ficoll. These Fc gamma R+ cells are mostly of typical small-lymphocyte morphology and do not bind detectable amounts of CYT-Ig, nor do they express the monoclonal antibody-defined VEP 13 determinant associated with Fc gamma R on LGL.

New ultrastructural observations: parallel tubular arrays in human T gamma lymphoid cells

T gamma cells are E-rosetting cells bearing Fc receptors for IgG (E+, Fc gamma + cells). Third population (non-T, non-B) lymphoid cells are also Fc gamma + cells and contain unique inclusions called parallel tubular arrays (PTA). Although T gamma cells and third population lymphoid cells should belong to a similar population of cells, previous ultrastructural studies on purified T gamma cells have failed to reveal the presence of PTA. In this study, we have unequivocally demonstrated PTA in the majority of T gamma cells using simple rosetting techniques. A total of 76 EA hu-rosettes and 108 EA ox-rosettes prepared from an E+ enriched fraction (using sheep erythrocytes as marker particles) were directly examined by electron microscopy. PTA were found in 87% of the EA hu-rosettes and 82% of the EA ox-rosettes. Ammonium chloride, commonly used in other laboratories to lyse erythrocytes during the purification procedure was found to cause a marked decrease in the number of ultrastructurally distinct PTA profiles. In contrast, hypotonic lysis had no effect on cellular ultrastructure. This study showed for the first time that T gamma cells are ultrastructurally similar to other Fc gamma + lymphoid cells and contain PTA as a distinct marker. The significance of our findings to the basic function of this E+ Fc gamma + lymphoid population is discussed.

Lymphocytes with parallel tubular structures: morphologically a distinctive subpopulation

Peripheral blood lymphocytes were fractionated in T, B and Null cell enriched subsets by means of sheep red blood cell rosette (ESRBC) sedimentation and nylon wool adherence. The ultrastructural features of these subpopulation were investigated. The T cell fraction in which the sheep erythrocytes were removed from the ESRBC rosette-forming cells (ESRBC-RFC) by lysis with ammonium chloride, consisted mainly of two morphologically distinctive subsets. The majority of the cells (80%) displayed a smooth surface membrane and had a high nuclear to cytoplasmic ratio with few cytoplasmic organelles. The other cell type (18%) had a relatively rough surface membrane, a low nuclear to cytoplasmic ratio, often an indented nucleus and numerous cytoplasmic organelles such as characteristic amorphous granules and sometimes parallel tubular structures (p.t.s.). If the T cells were obtained after mechanical vibration of the ESRBC-RFC, the majority of these cells appeared morphologically identical to this latter cell type. Cells with p.t.s. and amorphous granules were also demonstrated within the Null and B cell enriched fractions (50% and 25% respectively), though in the B cell enriched fraction this cell type is probably due to a contamination of Null cells. Previous observations had already demonstrated that these cells in the three fractions represent the Fc gamma receptor-bearing lymphocytes. The similarities suggest that the Fc gamma receptor-bearing and p.t.s. containing lymphocytes form a morphologically distinct subpopulation.

Comparison of cultures of human lymphocytes obtained following NH4Cl induced red blood cell lysis and Ficoll-Hypaque density gradient centrifugation

Lymphocyte thymidine uptake in leucocytes prepared by NH4Cl induced RBC lysis was compared with that of lymphocytes obtained following Ficoll-Hypaque centrifugation using polynomial regression dose response curves which adjusted for inherent subject variability. Eleven male subjects were studied. Heparinized blood was either layered in Ficoll-Hypaque or treated with 0.87% NH4Cl to induce RBC lysis. Phytohemagglutinin-P (PHA) dose response curves were determined for each subject using triplicate 5 day cultures. For each subject, at each Pha concentration ranging from 12.5 to 167micrograms/ml, triplicate mean cpm of Ficoll-Hypaque treated lymphocytes and NH4Cl treated lymphocytes were compared by the 2 tailed Student's T test. Responses of cultures of NH4Cl treated lymphocytes were significantly different (less than 0.05) from the responses of cultures of Ficoll-Hypaque treated lymphocytes for at least 2 PHA doses in 8 of the 11 subjects. The quadratic dose response curves were also significantly different (p less than 0.05) for 9 of the 11 subjects. A repeated measures quadratic regression was used to determine the best fit dose response curves for each of the experimental conditions. For Ficoll-Hypaque treated lymphocytes, mean cmp=44,977+1400.4 (PHA concentration)-5.90 (PHA concentration)2+ subject effect; s.e.=22,256; for NH4Cl treated lymphocytes, mean cpm=58,039+1022.8(Pha concentration)-5.32 (PHA concentration)2+ subject effect; s.e.=37,966. The p values from the F tests for significance of these quadratic regressions are different, F=1.91, d.f.=30,30; p less than 0.001. The lack of significance of the NH4Cl treated lymphocytes' does response quadratic regression and its larger s.e. indicates that the NH4Cl treated lymphocyte culture dose response curve is less predictable than that of Ficoll-Hypaque treated lymphocytes.

Characterization of human null cells isolated from peripheral lymphocytes by a simultaneous double-rosetting procedure

Human null cells were isolated from peripheral blood lymphocytes (PBL) by differential centrifugation on a Ficoll-Hypaque gradient of the PBL following simultaneous rosetting with erythrocyte indicators specific for B and T lymphocytes. Specifically, the T lymphocytes were rosetted with 2-aminoethylisothiuronium bromide-treated sheep erythrocytes (ShE), whereas the B lymphocytes were either rosetted with ShE coated with xenoantibodies against human gamma globulin or first sensitized with monoclonal antibodies to human Ig-like antigens and then rosetted with ShE coated with xenoantibodies against mouse gamma globulin. Approximately 90% of the lymphocytes isolated were null cells that did not bear detectable B-cell markers-that is, surface immunoglobulin and/or Ia-like antigens-or T-cell markers-that is, ShE receptors. The large majority of the null cells expressed receptors for the IgG Fc fragment (53-93%), C3 component (65-92%) and monkey erythrocytes (60-91%) but lacked receptors for the IgM Fc fragment and murine erythrocytes. The null cells exhibited high natural killer cell activity and antibody-dependent cellular cytotoxicity and were two- to four-fold active than the total PBL and the T-enriched cell fractions. The null cells, however, did not respond to stimulation with phytohaemagglutinin and failed to function as either stimulators or responders in an unidirectional mixed lymphocyte reaction.

Mixed rosette assay for the detection of T mu and T gamma lymphocytes

A mixed rosette assay is described for simultaneous detection of T lymphocytes and lymphocytes bearing receptors for the Fc Fragments of IgM (RFc mu) or IgG (RFc gamma) in unfractionated lymphocyte suspensions. For optimal detection of T lymphocytes, treatment of sheep erythrocytes with neuraminidase was necessary. ox erythrocytes labelled with fluorescein isothiocyanate and sensitized with either rabbit IgM or rabbit IgG anti-ox antibodies served as indicator erythrocytes for RFc mu or RFc gamma bearing lymphocytes. In periphral blood the percentage of RFc mu bearing lymphocytes was the same whether determined directly after isolation or after overnight incubation at 37 degrees C. Ratios of non-fluoresceinated sheep erythrocytes to senanti-ox antibodies served as indicator erythrocytes for RFc mu or RFc gamma bearing lymphocytes. In periphral blood the percentage of RFc mu bearing lymphocytes was the same whether determined directly after isolation or after overnight incubation at 37 degrees C. Ratios of non-fluoresceinated sheep erythrocytes to senanti-ox antibodies served as indicator erythrocytes for RFc mu or RFc gamma bearing lymphocytes. In periphral blood the percentage of RFc mu bearing lymphocytes was the same whether determined directly after isolation or after overnight incubation at 37 degrees C. Ratios of non-fluoresceinated sheep erythrocytes to sensitized fluoresceinated ox erythrocytes are critical in the mixed rosette assay; for simultaneous detection of T lymphocytes and RFc mu bearing lymphocytes 1 : 1, and for T lymphocytes and RFc gamma bearing lymphocytes 2 : 1. In both assays the rosette suspension was preincubated for 10 min at 37 degrees C and then centrifuged at 200 X g for 5 min. For optimal simultaneous detection of T lymphocytes and RFc mu bearing lymphocytes incubation at room temperature for at least 2 h was necessary and for T lymphocytes and RFc gamma bearing lymphocytes incubation at room temperature for at least 2 h was necessary and for T lymphocytes and RFc gamma bearing lymphocytes incubation at 4 degrees C for at least 2 h was essential. The percentages of RFc mu or RFc gamma bearing lymphocytes (T mu and T gamma respectively) in the T lymphocyte population determined by mixed rosette assay did not differ significantly from the percentages of RFc mu and RFc gamma bearing lymphocytes in lymphocyte suspensions enriched in T cells by E-rosette sedimentation. The mixed rosette assay is suitable for detection of T mu and T gamma cells in immune deficiency and auto-immune diseases and for analysis of the mononuclear cells in lymphoreticular malignancies.

Isolation of human T lymphocytes: comparison between nylon wool filtration and rosetting with neuraminidase (VCN) and 2-aminoethylisothiouronium bromide (AET)-treated sheep red blood cells (SRBC)

Isolation of human T lymphocytes by rosetting with SRBC, centrifugation on Ficoll-Hypaque gradients and lysis of SRBC, which reportedly affects the functional activities of lymphocytes, was compared to isolation of T lymphocytes by filtration through a nylon wool column. The two methods were similar in yields and purity of T lymphocytes. No selective loss of T cell subpopulations was found in T lymphocytes isolated by filtration through a nylon wool column as judged by the percentage of T gamma and T micron and the suppressor and helper activity in functional assays. Therefore, filtration through a nylon wool column is a useful method to purify T lymphocytes and has the advantage of being comparatively simple and quick to perform and of avoiding manipulations which may affect the functional activity of T lymphocytes.