Fetuin. In vitro effect on sheep erythrocyte rosette formation with human T lymphocytes.

Peripheral blood lymphocytes from six healthy control subjects were incubated in vitro with fetuin and enumerated for sheep erythrocyte rosette forming T cells. Significant enhancement of rosette-forming T lymphocytes was observed in a dose-related manner. The physical presence of fetuin is not required for this effect. Incubation of lymphocytes with human AB serum has no significant effect on the rosette formation. This enhancing effect of fetuin appears to be secondary to alteration in T lymphocyte surface receptors for sheep erythrocytes.     

Inhibitory effect of sheep erythrocyte fragments on rosette formation of human T lymphocytes with sheep red blood cells.

The effect of sheep red blood cells (SRBC) fragments on rosette formation of human peripheral T lymphocytes with SRBC was evaluated on the active and total T-rosette tests. The rosetting capacity of active rosette-forming cells was selectively and nearly completely inhibited by the pretreatment of lymphocytes with SRBC fragments. The decrease in total rosettes by blocking with SRBC fragments was almost parallel to that of active rosettes. SRBC fragments had no inhibitory effect on the rosetting capacity of a lymphocyte population in which active rosette-forming cells were removed by gradient centrifugation. These results suggested that active rosette-forming cells in human T lymphocytes have the receptors of high affinity for SRBC and these receptors readily bind SRBC fragments, resulting in block of rosette formation.     

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.     

Human erythrocyte rosette formation with mitogen-stimulated human lymphocytes — A marker for the demonstration of activated T-cells

Human lymphocytes after stimulation by various mitogens could be shown to make rosettes with washed uncoated human Group O rhesus negative erythrocytes (H-rosettes). Using purified T- and B-cell populations and exposing them to the action of mitogens it has been demonstrated that the cell responsible is the activated T-lymphocyte. The H-rosette is thus presented as a new marker for the demonstration of activated human T-cells.     

Perturbation of lymphocyte response to concanavalin A by exogenous cholesterol and lecithin

Incubation of lymphocytes with lecithin liposomes enriched with cholesterol, elevated the cholesterol level of the cells relative to phospholipids. Treatment of lymphocytes with pure lecithin liposomes resulted in the converse effect. Both these treatments resulted in suppression of the induction phase of the response to concanavalin A and were practically reversible. It is suggested that these changes induce modulations of the fluidity of the lymphocyte membrane which may also take place in vivo by serum lipoproteins. Based on this study, the possible effects of lipids on lymphocyte activation are discussed.     

T lymphocyte colony-forming capacity of patients with immunodeficiency diseases: relationship of colony formation to E rosette formation and lymphocyte proliferation.

The formation of T lymphocyte colonies was studied in 30 normal subjects and 12 patients with suspected abnormalities in immune function. The mean number of colonies per plate in normal subjects was 1.159 +/- 411 which represented a plating efficiency of 0.5-1.0%. When individual cells from colonies of these normal subjects were studied for membrane markers, greater than 90% were E rosette-positive and less than 1% were positive for surface immunoglobulins. Blood lymphocytes obtained from all 12 patients showed diminished colony-forming capacity when compared to normal subjects with a range of 0-311 colonies. Six patients had less than 50 colonies/plate. Colony formation was diminished in some patients who had normal E rosette formation and lymphocyte proliferation in liquid culture. Because of these discrepancies it appears that colony formation is not a direct reflection of E rosette formation and lymphocyte proliferation. Evaluation of T lymphocyte colony-forming capacity may prove useful as an additional in vitro assessment of lymphocyte function.     

Effects of succinylated concanavalin A on infectivity and syncytial formation of human immunodeficiency virus

The effects of various lectins on the infectivity of human immunodeficiency virus (HIV) type 1 was investigated. Among the 25 lectins investigated, 2 types of concanavalin A (Con A) and 3 types of phytohemagglutinin were found to inhibit HIV infection. Succinylated Con A (S-Con A) efficiently blocked HIV-induced formation of syncytia in a coculture of MOLT-4 cells and blocked cell-free infection by HIV of MT-4 cells. The HIV-binding study revealed that S-Con A only partially inhibited viral binding to cells, although the control Leu-3a monoclonal antibody strongly inhibited it. When S-Con A was added to cultures after the initiation of viral adsorption, the number of HIV antigen-positive cells that developed depended on the time interval before addition of the compound. S-Con A inhibited HIV infection even after viral binding to cells at 0 °C and further incubation at 37 °C for 1 day. These data suggest that S-Con A inhibited mainly the fusion process rather than viral binding to cells in exerting its anti-HIV activity.     

伴刀豆素A对红细胞在切变流场中取向的影响

红细胞流变特性的研究已成功地应用于临床诊断和治疗,特别是在心脑血疾病的诊断和治疗方面更是引人关注。红细胞在切变流场中的取向能力虽然仍处在基础理论研究阶段,但已显示出良好的应用前景,本论文报道了采用分子生物学方法和激光衍射技术研究伴刀豆素A对细胞在切变流场中的取向和变形的影响。结果发现：伴刀豆素A与红细胞膜带3蛋白表面的糖链结合后会引起红细胞变形指数（DI）和取向指数（OI）的改变,并且OI指数反应更加强烈。该现象对临床诊断和治疗都有重要意义。     

Studies on human lymphocytes in frozen tissue section: viability and spontaneous rosette formation with sheep erythrocytes.

Sixty to 70% viability of lymphocytes in frozen tissue section was obtained by using dimethylsulphoxide-containing medium as a cryoprotective agent and by conditioning time and temperature for freezing, making sections on a cryostat and thawing. The aviable and dead cells were differentiated by trypan blue exclusion test on section. Lymphocytes in tissue sections showed spontaneous rosette formation with sheep erythrocytes (E rosette) with specific localization for each lymphoid organ.     

Effects of cyclosporin A on in vitro lymphocyte response to autologous or allogeneic stimulation: influence of HLA phenotypes

In this study we investigated whether the interindividual variability of lymphocyte sensitivity to cyclosporin A (CsA) could be controlled by the HLA region. The models used were the in vitro primary and secondary autologous (AMLR) and allogeneic mixed lymphocyte (MLR) cultures of cells from 32 healthy subjects from our HLA reference panel. Our results show that CsA inhibited primary allogeneic MLR to a much greater extent than primary AMLR (-81 +/- 2% vs -38 +/- 8%, P less than 0.001). The same pattern was observed when cells harvested from CsA-treated primary cultures were rechallenged in secondary cultures with the original sensitizing stimulator cells (-40 +/- 6% vs -17 +/- 9%, P less than 0.05). No differences were observed in primary autologous and allogeneic cultures among responders of different HLA phenotypes. In contrast, the secondary responses did vary according to the HLA types: in secondary AMLR, CsA-priming did not lower, or even enhance, the proliferative responses of DR5+ and/or DR2+ lymphocytes (+7 +/- 13%), whereas it significantly lowered the responses of DR2-5- cells (-46 +/- 8%). In secondary MLR, lymphocytes proliferation was lowered by CsA-priming in all but DRW11(5)+ subjects (-45 +/- 7% vs +2 +/- 23%, P less than 0.05). It is concluded that the individual HLA phenotype influences the pattern of lymphocyte sensitivity to CsA.     

Depression of lymphocyte response to concanavalin A in rabbits infected with Treponema pallidum (Nichols strain).

Peripheral blood lymphocytes isolated from rabbits in the early stages of Treponema pallidum infection responded poorly when exposed to concanavalin A in vitro. Maximal depression of blastogenesis occurred when lymphocytes were cultured in the presence of autologous serum in comparison with fetal calf or normal homologous rabbit serum.     

The lack of effect of histamine--protein conjugates on human lymphocyte responses to concanavalin A and histamine.

We have studied the effect of depleting human peripheral blood lymphocytes (PBL) on plates coated with histamine-rabbit serum albumin (H-RSA) or control (E-RSA) conjugates, on the concanavalin A (Con A) response and the histamine suppression of Con A responses. Low H10-RSA-substituted conjugate depletion had little effect on [3H]-thymidine incorporation of Con A-stimulated cells compared to control (E10-RSA) conjugates and unseparated cells, but significantly increased unstimulated cell counts, therefore reducing stimulation index (SI). Highly histamine-substituted (H30-RSA) and control (E30-RSA) conjugates decreased SI in a similar way, but also decreased the [3H]-thymidine incorporation of Con A-stimulated cells. Histamine suppression of Con A responses was reduced by both E10- and H10-RSA-coated plates at suboptimal but not optimal mitogen concentrations. The induction of Con A-induced suppressor cells was unaffected by prior depletion of cells on H10- or E10-RSA conjugate-coated plates. Addition of H10- and E10-RSA to Con A cultures had a slight enhancing effect on transformation, but no effect on histamine suppression of the Con A response. Thus, whilst it is clear from other studies in vitro that functional histamine receptors are present on suppressor T cells, the results presented here show that histamine-protein conjugates do not specifically bind to histamine receptor-bearing human peripheral blood suppressor T lymphocytes.     

Suppression of lymphocyte response to concanavalin A by mucopolysaccharide material from Treponema pallidum-infected rabbits.

The testicular fluid and serum from rabbits infected intratesticularly with Treponema pallidum inhibited the mitogenic response of normal rabbit peripheral blood lymphocytes to concanavalin A. Mucopolysaccharide material present in the testicular fluid and serum was associated with the lymphocyte-inhibitory activity. Degradation of the mucopolysaccharide material with hyaluronidase resulted in the loss of the inhibitory activity of testicular fluid and serum of T. pallidu-infected rabbits.     

Detection and quantitation of IgG on the surface of human lymphoid cells by rosette formation with protein A-coated sheep red blood cells

Sheep red blood cells coated with protein A of Staphylococcus aureus (SpA) form rosettes with human lymphoid cells with surface-associated IgG and with cells treated with antibodies of the IgG class against some of the cell membrane antigens. Inhibition of rosette formation by SpA was used for quantitation of immunoglobulins on the cell surface. The sensitivity of the method permits the quantitation of 10⁴ – 10⁵ molecules of IgG receptors and detected less than 10⁴ antibody molecules of the IgG class bound to the surface of IgM-producing cells. This method seems to be suitable for detection and quantitation of membrane-associated antigens including immunoglobulins.     

Decrease in microviscosity of lymphocyte surface membrane associated with stimulation induced by concanavalin A.

CM factor (CVF) - treated normal mouse serum produced a profound inhibition of the antibvody responses, affecting IgG responses more than IgM, and being T-dependent more than T-independent, but no part of the response being unaffected...     

Depression of lymphocyte response to mitogens in sheep infected with tick-borne fever

Lymphocytes obtained from sheep experimentally infected with Cytoecetes phagocytophila, the causative agent of tick-borne fever, showed reduced blastogenesis induced by the mitogens phytohaemagglutinin and E. coli lipopolysaccharide. The period of reduced lymphocyte reactivity coincided with the period of parasitaemia and leucopenia.     

Amphotericin B modifications of peripheral blood lymphocyte and tonsil lymphocyte responses to concanavalin A

Peripheral blood lymphocytes (PBL) were shown previously to be activated to incorporate ³H-thymidine by concanavalin A (con A). Amphotericin B (Am B) was reported to be both immuno-enhancing and suppressive. We investigated the response of PBL and tonsil lymphocytes (TL) to con A in culture, and the effect of Am B on these responses. PBL were activated by con A as expected, and the magnitude of the response diminished as cell density increased. The responses of PBL usually were significantly enhanced by Am B at 2.5 or 5 μg/ml, but 10 μg Am B/ml significantly inhibited the con A response. TL had relatively high rates of spontaneous proliferation, but Am B was a potent inhibitor of this. TL responded to con A just as well as PBL, and Am B strongly inhibited these responses too. When TL were cultured with various doses of con A in the presence of 5 or 10 μg Am B/ml, the shape of the dose curves resembled those of PBL stimulated in the absence of Am B except that the incorporation of ³H-thymidine increased with increasing cell density. It was concluded that Am B at 2.5–5.0 μg/ml enhanced the response of PBL to con A and suppressed the response at 10 μg/ml. All doses of Am B inhibited both spontaneous proliferation and con A-induced proliferation in TL. In spite of this inhibition, the TL population responded to various doses of con A in the presence of Am B.