Studies on phagocytosis of unopsonized rabbit erythrocytes by human monocytes

Monolayers of freshly isolated human monocytes are known to ingest particulate activators of the human alternative complement pathway. The ingestion of rabbit erythrocytes, ER, by human monocytes in serum-free medium was studied. The process is Mg2+-dependent and optimum phagocytic activity was obtained at approximately 20 mM MgCl2. Preincubation of mononuclear leukocytes increased the number of monocytes ingesting ER by at least twofold and this involved de novo protein synthesis, as evidenced by inhibition with cycloheximide. However, preincubation of the mononuclear leukocytes for longer periods (greater than 4 hr) caused a decrease in the percentage of ingesting monocytes. No inhibition of ingestion of ER was observed by cobra venom factor (CVF) or F(ab')2 rabbit anti-human C3 of F(ab')2 murine monoclonal anti-human Bb, known to inhibit C3 convertase activity. The ingestion was also not inhibited by (a) rabbit anti-human CR1, (b) OKM1 or anti-MO1, two monoclonal anti-CR3 antibodies, (c) goat anti-human IgG Fc receptor, or (d) mannan, a competitive inhibitor of ligand uptake by the mannosyl-fucosyl receptor (MFR). In contrast, ingestion was inhibited by glucan particles of yeast.     

Studies on human monocytes with a multiparameter cell sorter.

Suspensions of human lymphocytes and monocytes separated by the Ficoll-hypaque method from the peripheral blood show a Coulter volume distribution, measured with a multiparameter cell sorter, characterized by a minor peak at 500 mu3, containing 5-15% of the cells, and a major peak at 200 mu3. Using fluorescent latex particles we have found that the monocytes, the cells that ingest the latex particles, all lie in the 500 mu3 peak; conversely, all of the cells in the 500 mu3 peak are monocytes. When the cell suspensions are incubated, the monocytes increase both the average volume and in absolute numbers. The number of monocytes approximately doubles during 3 days of incubation, when it reaches its maximum value. At that time we have found that all of the monocytes lack receptors for sheep red blood cells and all possess receptors for human gamma-globulin. The increase in monocyte number appears, therefore, to arise from the enlargement of "monocyte presursors" that resemble lymphocytes in volume and resemble both the monocytes and the B lyphocytes with respect to surface sheep red blood cell and human gamma-globulin receptors.     

Fibronectin-enhanced phagocytosis of an alternative pathway activator by human culture-derived macrophages is mediated by the C4b/C3b complement receptor (CR1)

We examined the ability of human monocytes and culture-derived macrophages under serum-free conditions to phagocytose desialated sheep erythrocytes (E), an activator of the alternative pathway of human complement. Freshly derived monocytes ingested desialated erythrocytes, but the degree of phagocytosis varied among individual donors. However, exposing the phagocyte to intact plasma fibronectin (Fn) had no effect on monocyte phagocytosis. Macrophages derived from monocytes in culture were far more efficient at ingesting desialated E, and the extent of phagocytosis was proportional to the degree of desialation. Although exposure of macrophages to substrate-bound Fn or fluid-phase Fn enhanced the phagocytosis of desialated E, pretreatment of desialated E with Fn did not enhance phagocytosis, demonstrating that Fn acted through an interaction with the macrophages. Fn-enhanced phagocytosis of desialated E was inhibited by treating macrophages with a monoclonal antibody to the C4b/C3b receptor (CR1), but not with a monoclonal antibody to the receptor for C3bi (CR3). Addition of cobra venom factor (CVF) to the macrophages also inhibited Fn-enhanced phagocytosis of desialated E. Phagocytosis of IgG-sensitized E, either in the absence or in the presence of Fn, was not significantly affected by anti-CR1 or CVF, demonstrating that these reagents did not lead to a general inhibition of phagocytosis. These experiments suggest that macrophages may deposit enough C3b onto desialated E to cause CR1-mediated phagocytosis in the presence of Fn. The ability of macrophages to opsonize and ingest foreign particles that activate complement may be critically important in areas of inflammation where concentrations of serum-derived specific opsonins may be inadequate.     

The effect of fibronectin on the processing of C1q- and C3b/bi-coated immune complexes by peripheral blood monocytes

In the past several years, it has been demonstrated that plasma fibronectin (Fn) binds to the C1q subunit of the complement system. The effect of Fn on the processing of immune complexes containing C1q and C3b by human peripheral blood monocytes was investigated. Preincubation of monocytes with Fn causes a significant increase in attachment of sheep erythrocytes coated with IgM and C1q (EIg-MC1q), but does not mediate their ingestion. EIg-MC1q attach to the Fn-treated monocytes via the C1q receptor because Fab anti-Fn antibodies do not inhibit their attachment to the monocytes. In addition, Fn-treated monocytes exhibit no change in C1q receptor number or affinity compared with monocytes treated with buffer. Fn mediates the phagocytosis of C3b/bi-coated particles, and C1q can enhance this process in two ways. First, phagocytosis of particles bearing C3b/bi and Fn is enhanced by the presence of C1q on the immune complex. Second, monocytes on Fn-coated surfaces ingest more particles if they are coated with both C3b/bi and C1q, compared with particles coated with either C3b/bi or C1q alone.     

Immunoglobulin-positive mononuclear cells in human peripheral blood: detection by mixed anti-globulin and direct anti-globulin-rosetting reactions.

Ig-bearing mononuclear cells were identified in Ficoll-Hypaque preparations of human peripheral blood by using mixed anti-globulin (MAG) and direct anti-globulin rosettes; indicator cells consisted of sheep erythrocytes coated with human F(ab')2 or anti-F(ab')2 antibody, respectively. Of the cell population isolated from 10 normal subjects, a mean of 68% was lymphocytes. However, fewer than 50% of the cells with detectable surface Ig were lymphocytes. On viable cell preparations using chromic chloride-treated sheep erythrocytes (CrCl3SRBC) coated with anti-F(ab')2 antibody, a mean of 20.1% of the lymphocytes formed rosettes, i.e., were B. Up to 6% of peripheral blood lymphocytes formed mixed Ig-rosettes and E-rosettes. On viable lymphocytes using F(ab')2-coated CrCl3SRBC, MAG rosettes were insensitive in detection of B lymphocytes. Formaldehyde treatment of lymphocytes increased the number of B cells detectable to 25.5% of the lymphocyte population. Study of T-enriched and B-enriched populations showed that the observed increase in B cell reactivity was real and not due to MAG-rosetting T cells. A one-stage procedure for T and B lymphocyte separation is described.     

Phenotypic markers for the feline monocyte: rosette formation with human erythrocytes and a monoclonal antibody which binds myeloid cells

A small population of cells with the ability to form rosettes with human erythrocytes was found in feline peripheral blood leukocytes (PBL) (10%) and bone marrow (9%), but not in purified granulocyte preparations, thymus, and lymph node tissues. The morphologic appearance and ability to phagocytize latex beads indicated these cells were monocytes. A monoclonal antibody, CM277, with a binding specificity for feline peripheral blood phagocytes was also characterized. Immunofluorescent microscopy revealed CM277 to bind specifically to monocytes and polymorphonuclear neutrophils. The binding of CM277 to monocytes was also shown by human erythrocyte-rosette formation wherein there was a high degree of correlation between these two phenotypic markers for cells ingesting latex beads. Monocytes, polymorphonuclear neutrophils, and T lymphocytes of the cat rosette with guinea pig erythrocytes (GPE) and using CM277 we were able to determine the contribution of the former two cell types to the GPE-rosetting population. Monocytes and polymorphonuclear neutrophils comprised the majority of the GPE-rosetting cells in fresh PBL (greater than 60%), but after culturing overnight, there was a substantial decrease in these cells (less than 35%). In contrast, GPE-rosetting T lymphocytes comprised approximately 10% of the cells in fresh PBL, and after in vitro culture for 1 day they constituted 35-45% of all cells. The removal of monocytes by human erythrocyte-rosetting did not affect the pokeweed mitogen-induced synthesis of Ig, but did lead to an increased production of interleukin 2. Removal of the GPE-rosetting population from PBL resulted in a marked decrease in interleukin 2 production, pointing to a positive contribution of GPE-rosetting T lymphocytes to the synthesis of this lymphokine.     

The use of electroblotted antigens of Trichostrongylus colubriformis to induce proliferative responses in sensitized lymphocytes from sheep

Merino sheep were immunized against the intestinal nematode, T. colubriformis, by repeated infections, and proliferative responses of their peripheral blood lymphocytes (PBL) against parasite extracts and excretory-secretory (ES) antigens were monitored over 130 days. Maximal responses occurred 7-14 days after challenge. The ability of soluble proteins and parasite antigens to induce proliferation was compared with that of antigen-bearing particles obtained after antigen was adsorbed onto nitrocellulose. Blank particles increased c.p.m. two- to three-fold above that obtained in medium alone, and to elicit proliferative responses of comparable magnitude between 10 and 100 times more antigen was required when antigen-bearing particles were used instead of soluble extracts or defined proteins. Blood leucocytes as well as T-cell lines established by stimulation with parasite antigens in vitro reacted to moieties of from 5000 to 38,000 mol. wt in ES antigens on nitrocellulose particles. Direct comparisons of T-lymphocyte responses with antibody responses as assessed by immunoblots revealed different profiles of immunogenicity among ES proteins within individual sheep, but the 10,000, 30,000 and 75,000-90,000 mol. wt proteins were immunodominant. These proteins were also those consistently recognized by T-lymphocytes and sera from sheep immunized with ES proteins in adjuvant. Thus, this technique can be applied to identify parasite material which is immunogenic for T-lymphocytes, but the sensitivity of the procedure in sheep is less than reported in human studies.     

Identification of human peripheral T cell antigens.

A new type of differentiation antigens on human T cells was demonstrated by using a heterologous anti-human T cell serum (ATS). This type of antigen, referred to as human peripheral T cell antigen (HPTA), was found on peripheral T cells and medullary thymocytes, but not on cortical thymocytes and B cells. The percentage of ATS-reactive lymphocytes in human peripheral lymphoid organs was correlated with that of cells rosetting with sheep erythrocytes, but contrasted with the number of B cells defined by the presence of a complement (C) receptor or by rabbit anti-human B cell serum (ABS). ATS also reacted with T cells purified by nylon fiber column filtration but ABS did not. Chronic lymphocytic leukemia cells rosetted with either sheep erythrocytes or erythrocyte-antibody-complement complexes were lysed by ATS and ABS, respectively. Mitogenic responses of blood lymphocytes to phytohemagglutinin (PHA) and concanavalin-A (Con A) were abrogated by treating them with ATS and C, whereas ABS suppressed only their response to Con A. Although numerous thymus cells rosetted with SRBC, only 14% were reactive with ATS. Quantitative absorption studies demonstrated that HPTA content of the thymus cells was much lower than that of lymph node cells. Anatomical localization of ATS-reactive lymphocytes in human lymphoid organs studied by immunofluorescence indicated that they were present in the thymus-dependent paracortical areas of lymph node and in the medullary region of thymus. ABS, on the other hand, did not stain thymocytes but reacted selectively with the cells located in the lymphoid follicles of lymph node. These data, together with that from cell suspension studies, confirmed that HPTA were shared between medullary thymocytes and peripheral T cells.     

Comparative analysis of the heterogeneity of mononuclear cells present in adult and cord blood by simultaneous examination of multiple phenotypic characteristics

In an attempt to better relate specific membrane characteristics of human adult and cord blood lymphocytes to specific functional activities, the phenotypic differences that exist in these two populations have been examined. Cord blood cells have considerably more spontaneous suppressor cell activity than adult cells. A technique that allows cells to be examined simultaneously for their ability to ingest latex beads, react with specific monoclonal antisera, bind sheep erythrocytes, or react with the Fc portion of IgG was used. As well as assessing fresh populations, phenotypic changes that occur when such cells are held in culture or stimulated with phytohemagglutinin for 3 days were sought. Many differences were found when comparing these mononuclear populations. These included the observations that 12% of adult and 9% of cord blood E-rosette-forming cells ingest latex beads and that 9% of OKT3 reactive cells in both populations did not form E rosettes. In cord blood 58% of T cells that bind OKT8 do not form E rosettes. A similar percentage of cord blood T8-positive cells express a receptor for Fc gamma, such cells being very uncommon in adult blood. Four "monocyte" subpopulations were identified in both samples. One such population (an OKM1- and Fc gamma-positive, nonphagocytic cell) was three times more common in cord blood. In cord blood some OKM1-positive cells also appeared to be simultaneously OKT8 positive. These phenotypic variations forward populations that may be candidates responsible for the functional differences noted in vitro.     

Genetic differences in lymphoid tissue reactivity during liver regeneration in mice of different lines]

The transfer of lymphocytes together with sheep erythrocytes from partially hepatectomized mice to syngenous lethally irradiated mice (CAB and C57BL) increased the number of antibody forming cells in the recipient's spleen. The lymphocytes of CBA mice acquired this ability much earlier after the operation (in 4 hours) than those of the C57BL mice (in 17 hours). After the transfer of lymphocytes in the semisyngenous system there was a decrease of antibody forming cells during subsequent recipient's immunization with sheep erythrocytes; this was the result of the graft versus host reaction. The latter reaction was less marked in the operated than in control mice. These changes also occurred earlier after the operation in the CBA than in C57BL mice.     

Nucleotide profiles of normal human blood cells determined by high-performance liquid chromatography

An anion-exchange high-performance liquid chromatography method has been used to quantitate the intracellular purine and pyrimidine nucleotides in extracts of pure lymphocytes, monocytes, neutrophils, eosinophils, erythrocytes, and platelets isolated from the blood of healthy human donors. For accurate and reproducible measurements of the nucleotide profiles in different types of pure leukocytes, the cell suspensions have to be free of platelets and erythrocytes. Incubation of the purified leukocytes for 1 h at 0 degrees C did not alter the nucleotide concentrations but reduced the interdonor variation to 10%. Incubation of purified lymphocytes for 1 h at 37 degrees C caused considerable changes in the relative concentrations of the adenine, guanine, uracil, and cytosine nucleotides. During this incubation the cell viability, the cell number, and the ATP:ADP ratio decreased. Incubation of monocytes and granulocytes for 1 h at 37 degrees C caused considerable loss of cells and/or cell death. For erythrocytes and platelets reproducible nucleotide concentrations were obtained after extraction of freshly isolated cells. During storage of erythrocytes, both at 0 degrees C and at 37 degrees C, a decrease in the ATP:ADP ratio was detected. In all cell types the predominant nucleotides were purine nucleotides, especially adenosine triphosphate. The relative concentrations of the adenine, guanine, uracil, and cytosine nucleotides were very reproducible per cell type and appeared to be characteristic for each cell type. The total nucleotide content was nearly the same for all cell types except erythrocytes, when expressed per microgram of protein. The described methods for purification and storage of blood cells will be useful for comparison of blood cells from healthy donors with those of patients, for example, leukemia patients, in which deviations of the purine and pyrimidine metabolic enzymes have already been described.     

Binding of fluid-phase complement components C3 and C3b to human lymphocytes.

It is known that a population of B-lymphocytes has receptors for the third component of complement, C3, and that these lymphocytes may be identified by their ability to form rosettes with sheep erythrocytes coated with covalently bound fragments of complement component C3. Human tonsil lymphocytes, enriched for B-cells, form rosettes with sheep erythrocytes coated with antibody and complement components C1, C4b and C3b (EAC143b cells). Fluid-phase C3 will inhibit rosette formation between EAC143b and human tonsil lymphocytes over the same concentration range as fluid-phase C3b. C3 is not cleaved to C3b during incubation with lymphocytes or with lymphocytes and EAC143b cells. Fluid-phase 125I-labelled C3 and 125I-labelled C3b bind to lymphocytes in a specific manner. The characteristics of binding of both radioiodinated C3 and radioiodinated C3b are very similar, but the binding oc C3 is again not a result of cleavage to C3b. Salicylhydroxamic acid does not inhibit binding of 125I-labelled C3 to tonsil lymphocytes at concentrations that completely inhibit binding of 125I-labelled C3 to EAC142 cells via the nascent binding site of C3b. It is concluded that C3 and C3b share a common feature involved in binding to lymphocytes bearing receptors for the third component of complement.     

Influence of several experimental conditions on the quantity of E- and EAC-rosette forming cells in peripheral human blood]

The authors analysed the influence of some conditions of studying the rosette-formation between the human peripheral blood lymphocytes and sheep red blood cells, not loaded (a) and loaded with antibodies and a complement (b). It was shown that rosette formation depended on the temperature at which the experiment was conducted. Thus, after the incubation of a mixture of cells at 37 degrees C, and then at 4 degrees C the number of rosette-forming cells was greater than after the incubation at 4 degrees C alone. Substances used for their fixation also influenced the formation of rosettes: in the treatment of erythrocytes with formalin, tannin and glutaraldehyde, as well as introduction of the latter into the mixture of erythrocytes and leukocytes considerably increased the number of a and b (the sum of T- and B-lymphocytes exceeded 100%). Among a and b in such experimental conditions there was seen a great number of monocytes and of segmented leukocytes. Fixation of smears prepared from a mixture of cells after the incubation in formalin vapour did not lead to such increase in the number of rosette-forming cells. Apparently in case of using glutardehyde, formalin and tannin cells for the treatment of cells additional investigations are necessary with the purpose of identification of a and b as T- and B-lymphocytes.     

Tumor necrosis factor induction by Candida albicans from human natural killer cells and monocytes

Other investigators have previously reported that TNF has been induced from macrophages by bacteria and, more recently, from NK cells by certain tumor cells. Sendai virus has also been reported to induce TNF from macrophages. We report here that an opportunistic fungi, Candida albicans, can also induce TNF, not only from human monocytes, but also from Percoll-fractionated large granular lymphocytes (LGL) which mediate NK function. Incubation of monocytes of LGL with C. albicans for 8 h was sufficient for detection of TNF release and peak induction was observed at 24 h. Induction of TNF from LGL did not require the participation of monocytes or T cells because treatment of the LGL with CD14 or CD15 to eliminate contaminating monocytes and CD3, CD4, or CD8 to eliminate contaminating T cells did not decrease the level of TNF produced from the treated LGL. Small T cells recovered from the denser fractions of the Percoll gradient had no ability to produce TNF, even when 10% monocytes were added to the T cells to provide accessory function. The phenotype of the TNF-producing LGL was CD2+, CD11+, CD16+, NKH1+, LEU7-. The TNF produced by both monocytes and LGL was neutralized by specific monoclonal and polyclonal anti-TNF but not by monoclonal antilymphotoxin. These results indicate that TNF production is a normal response of monocytes and LGL to stimulation by fungi such as C. albicans and that the release of TNF may be related to its ability to activate effector function to control Candida growth, which we have shown earlier for neutrophils with TNF.     

Influence of tumor necrosis factor-alpha on the ability of monocytes and lymphocytes to destroy intraerythrocytic Plasmodium falciparum in vitro

It has been shown that administration of TNF-alpha causes an increase of survival of plasmodium-infected mice. However, this anti-parasitic effect cannot be reproduced in vitro upon direct incubation of the cytokine with the parasite. This suggests that TNF-alpha may act through modulation of some plasmodicidal mechanism not yet clarified. We evaluated the effect of exogenous TNF-alpha on the phagocytosis of Plasmodium falciparum-infected erythrocytes by monocytes and its influence on the ability of monocytes and lymphocytes to inhibit parasite growth. The capacity of endogenous TNF-alpha to influence the ability of monocytes to inhibit the parasite was also verified. We found that addition of 33 ng TNF-alpha/mL to cultures of human monocytes and P. falciparum-infected erythrocytes increased the phagocytic index from 3.8 to 7.8 in the presence of serum containing P. falciparum antibody. TNF-alpha increased the capacity of monocyte plus lymphocyte to inhibit parasite growth by about 3 times at 0.5 and 5 ng/mL. Sera from severely ill P. falciparum-infected individuals inhibited the parasite growth, but addition of anti-TNF-alpha antibody was unable to modify this inhibition. These data show that TNF-alpha can increase the phagocytic capacity. This was probably due to an increased expression of Fc receptors on monocytes or to the modulation of Fc receptor signaling pathways by signals originating from the binding of TNF-alpha to its receptors. TNF-alpha also acted on lymphocytes plus monocytes by increasing the inhibition of P. falciparum by a mechanism not related to phagocytosis. These findings suggest that TNF-alpha has a pleiotropic anti-malaria effect and that this protective effect depends on the interplay of different factors, such as monocytes/macrophages, lymphocytes, and antibodies, in addition to other cells and molecules.     

Correlation between phagocytic and membrane surface properties reflected by partitioning of human peripheral blood monocytes in two-polymer aqueous phases

Human peripheral blood monocyte-enriched fractions (identified by staining for peroxidase and by sizing) were obtained by velocity sedimentation at unit gravity of peripheral blood mononuclear cells. They were then fractionated by countercurrent distribution (a multiple-extraction procedure) in a charged Dextran/poly(ethylene glycol) aqueous phase system. The monocytes remained viable after the separation (order of 90%). Cells obtained from different cavities along the extraction train were tested for their ability to phagocytize latex particles. With increasing partition coefficient (presumably higher charge-associated membrane properties) the ratio of monocytes that phagocytized to monocytes that did not phagocytize increased appreciably. When, however, monocytes were permitted to phagocytize particles prior to countercurrent distribution, an increase in partition coefficient was associated with an appreciable decrease in the above-specified ratio. Control experiments indicate that the observed change in partitioning behavior cannot be ascribed to an alteration in size and/or density of the monocytes as a function of phagocytosis. It may be due to the internalization of charged surface groups during phagocytosis. We conclude that there is a correlation between the surface properties of monocytes (as reflected by partitiartitioning behavior cannot be ascribed to an alteration in size and/or density of the monocytes as a function of phagocytosis. It may be due to the internalization of charged surface groups during phagocytosis. We conclude that there is a correlation between the surface properties of monocytes (as reflected by partitioning) and their ability to ingest particles. Furthermore, an alteration in the surface charge-associated properties of monocytes as a consequence of phagocytosis is indicated by the cells' reduced partition coefficient.     

Separation of and cholesterol synthesis by human lymphocytes and monocytes.

We have devised techniques for the isolation of human monocytes which do not require the adherence of the cells to a surface. In 15 consecutive experiments using density-gradient and counterflow centrifugations, a population of mononuclear cells that was 75 +/- 11% monocytes was obtained within 2 hours of venipuncture. These cells had never been pelleted and represented approximately three-fourths of the monocytes that had been present in the whole blood. In another 22 consecutive experiments using sedimentation in gelatin followed by counterflow and density-gradient centrifugations, a population of lymphocytes that was 99.5 +/- 0.5% pure and a population of monocytes that was 94 +/- 3% pure were obtained within 3 hours of venipuncture. When these freshly isolated cells were incubated in the lipoprotein-deficient fraction of serum (d > 1.21 g/ml) or in solvent-extracted serum, the monocytes incorporated 10-20 times more [2-(14)C]acetate into sterols than did the lymphocytes. Monocytes were seen to constitute between 6 and 46% of the mononuclear cells isolated from normal individuals by the usual density-gradient centrifugation of whole blood on Ficoll-Hypaque. We conclude that future studies of cholesterol metabolism utilizing human mononuclear cells must take into account this large variation in the percentage of monocytes and their disproportionately greater activity during short-term incubations in media that induce sterol synthesis.-Fogelman, A. M., J. Seager, M. Hokom, and P. A. Edwards. Separation of and cholesterol synthesis by human lymphocytes and monocytes.     

Activation of purified human thymus-derived (T) cells by mitogens. II. Monocyte- macrophage potentiation of mitogen-induced DNA synthesis.

Thymus-derived (T) cells from peripheral blood were purified by rosette formation with neuraminidase-treated sheep red blood cells (SRBC) and centifugation on Ficoll-Hypaque. T cells recovered from the pellet were freed of SRBC by treatment with Tris-NH4Cl. T cells purified by this method showed a diminished ability to take up 3H-thymidine (3H-TdR) after mitogen stimulation when compared to the mitogenic response of an equal number of autologous peripheral blood mononuclear lymphocytes (PBL). Autologous monocytes restored the capacity of purified T cells to take up 3H-TdR in the presence of phytohemagglutinin (PHA) or Concanavalin A (Con A). The effect was proportional to the number of monocytes added. Similar restorative effects could be obtained with allogeneic or xenogeneic monocytes. These data suggest that the mitogenic stimulation of human PBL and Con A may reflect the participation of more than one cell type: the T cells and monocyte and that the genetic origin of the monocyte is not critical for augmentation of the mitogenic activation of human T cells.     

Nonspecific human lymphocyte-mediated cytotoxicity induced by immobilized IgG aggregate

Normal human lymphocytes were induced to lyse nonsensitized erythrocytes when concomitantly incubated on immobilized IgG aggregate with various erythrocyte target cells. These included ox, sheep, chicken, and human red blood cells. Only immobilized aggregate would initiate cytolysis. The IgG aggregate was prepared from normal, healthy adult donors and did not possess target cell specificity (e.g., human erythrocyte lysis was initiated by autologous IgG). Normal human lymphocytes could be induced to lyse the red blood cell targets only after a preincubation with adherent mononuclear cells; however, freshly prepared lymphocytes depleted of IgG-FcR^? cells were cytolytic. Cytolysis induced by immobilized IgG-aggregate can be distinguished from NCMC and ADCC by its requirement for immobilized IgG aggregate and the absence of target cell specificity in the IgG-aggregate preparation.     

人和猴T淋巴细胞表面TRBC受体及其配体不同于E2分子和CD2的配体

CD2 (E receptor, LFA-3 receptor) and E2 molecules (Bernard, 1988) on human T lymphocytes, CD58 (LFA-3, lymphocyte function associated antigen 3) on human erythrocytes and S14,S42,S110-220 molecules (Bernard, 1987) of sheep erythrocytes are involved in rosette formation of human T lymphocytes with human or sheep erythrocytes. Rosette formation of human and macaque pan-T lymphocytes with tree shrew (Tupaia belangeri) red blood cells (TRBC) (TRBC rosette) has shown different physicochemical properties from that of rosette formation with sheep red blood cells (E rosette) (Ben, 1985). CD2, CD3/TCR complex, CD5, CD6, and CD7 are not involved in TRBC rosette formation (Zheng, 1990). In order to know whether E2, LFA-3,S14,S42 and S110-220 molecules are involved in TRBC rosette formation or human and macaque T lymphocytes, rosette inhibition and antigenic modulation or co-modulation were performed with relevant monoclonal antibodies (McAbs), and hemolytic assay and slide agglutination were also conducted. TRBC rosette formation of human and rhesus monkey PBL was not blocked by E2 McAb (inhibition rate 2.8% and 2.1%, respectively). In contrast, human E rosette formation was obviously blocked at inhibition rate of 49.8% and macaque E rosette formation was slightly inhibited (13.3%). The modulation or co-modulation of E2 molecule with E2 McAb did not affect human TRBC rosette formation. Similar results were shown in rosette formation inhibition of Jurkat cells.(ABSTRACT TRUNCATED AT 250 WORDS)