Cytochemical profile of immunoregulatory T-lymphocyte subsets defined by monoclonal antibodies

Immunogold staining in combination with enzyme cytochemistry was used to determine the cytochemical profile of the immunoregulatory T-lymphocyte subpopulations defined by the monoclonal antibodies OKT3, OKT4, OKT8, and OKM1 in normal peripheral blood. Leukocyte suspensions were first incubated with the monoclonal mouse antibodies and then with colloidal gold-labeled goat antimouse antibodies. The cells were fixed and cytocentrifuge preparations were made. Cytochemical reactions for the detection of peroxidase, acid alpha-naphthyl acetate esterase, acid phosphatase, and beta-glucuronidase were performed on these preparations. Under light microscopy, lymphocytes reacting with the monoclonal antibodies had numerous dark granules around their surface membrane. In the cytoplasm the intracellular enzymatic activities were stained. The T-lymphocytes were characterized by a dot-like activity for the three enzymes. No significant difference could be found between the cytochemical profile of the T-helper (OKT4 positive) and T-cytotoxic suppressor cell populations (OKT8 positive). A few cells with lymphocyte morphology reacted with the OKM1 monoclonal antibody. Their cytochemical characteristics were different from those of mature T-cells (OKT3 population) or mature monocytes. From the comparison of their cytochemical characteristics, we can conclude that there is little correlation between the immunoregulatory T-lymphocyte subsets defined by these monoclonal antibodies and those defined by Fc receptors.     

An immunogold-silver staining method for detection of cell-surface antigens in light microscopy

An immunogold-silver staining technique for detection of cell-surface antigens in cell suspensions was developed. Leukocyte cell suspensions were first incubated with monoclonal antibodies directed against cell-surface antigens and then with colloidal gold-labeled goat anti-mouse antibodies. Cytocentrifuge preparations of the cell suspensions were immersed in a physical developer containing silver lactate and hydroquinone as reducing substance. The preparations were then counterstained and mounted. In light microscopy, cells reacting with the monoclonal antibodies showed dark granules on their surface membrane. An optimal morphology, as revealed by a May-Grünwald-Giemsa counterstain, permitted accurate cell identification. The labeling was influenced by the gold particle diameter and the concentration of the gold reagents, by the duration of incubation in the physical developer, and by the composition and temperature of this medium. The T-cell subsets enumerated with this method in the peripheral blood of normal adults were identical to those found with other methods. The sensitivity of the technique was comparable with that of immunofluorescence microscopy. This immunogold-silver staining procedure proved to be a reliable tool for detection of cell-surface antigens in light microscopy.     

Immunogold-silver staining method for light and electron microscopic detection of lymphocyte cell surface antigens with monoclonal antibodies

We used the immunogold-silver staining method (IGSS) for detection of lymphocyte cell surface antigens with monoclonal antibodies in light and electron microscopy and compared this procedure with the immunogold staining method. Two different sizes of colloidal gold particles (5 nm and 15 nm) were used in this study. Immunolabeling on cell surfaces was visualized as fine granules only by IGSS in light microscopy. The labeling density (silver-gold complexes/cell) and diameters of silver-enhanced gold particles on cell surfaces were examined by electron microscopy. Labeling density was influenced not by the enhancement time of the physical developer but by the size of the gold particles. However, the development of shells of silver-enhanced gold particles correlated with the enhancement time of the physical developer rather than the size of the colloidal gold particles. Five-nm gold particles enhanced with the physical developer for 3 min were considered optimal for this IGSS method because of reduced background staining and high specific staining in the cell suspensions in sheep lymph. Moreover, this method may make it possible to show the ultrastructure of identical positive cells detected in 1-micron sections counterstained with toluidine blue by electron microscopy, in addition to the percentage of positive cells by light microscopy.     

An immunogold-silver staining method for detection of cell surface antigens in cell smears

We developed an indirect immunogold-silver staining method for detection of leukocyte cell surface antigens in cell smears. Air-dried and fixed cytocentrifuge preparations or smears of peripheral blood leukocytes were incubated with monoclonal antibodies (MAb) and colloidal gold-labeled secondary antibodies. The preparations were post-fixed and silver enhancement was performed. The smears were counterstained with May-Grunwald-Giemsa and examined in brightfield light microscopy. The morphology of the cells was well preserved. Leukocytes reacting with the MAb showed black granules on their surface membranes. The intense immunostaining and the low background allowed a rapid enumeration of the positive cells. The labeling could be detected with high sensitivity by epipolarization microscopy. This immunogold-silver staining method was used to quantify T- and B-lymphocytes and natural killer cells in buffy coat smears of normal adult blood. These lymphocyte subsets correlated well with those obtained in smears with the alkaline phosphatase-anti-alkaline phosphatase (APAAP) method and with those found by labeling of mononuclear cells in suspension with immunogold-silver staining. This immunogold-silver staining method forms a good alternative to immunoenzyme methods for study of hematologic cells. In addition, it could be a general procedure for detection of cell surface antigens in all kinds of cell smears.     

Three-dimensional distributions of desmin and vimentin in cultured hamster cardiomyocytes using the immunogold deep-etching replica technique

The distributions of desmin and vimentin intermediate filaments in cultured hamster heart cells were examined by immunofluorescent microscopy and an immunogold deep-etching replica technique in combination with electron microscopy. Fluorescent studies showed the overall staining patterns of the myocytes as well as the fibroblasts. Monoclonal antibodies (Da, D₃) to desmin showed punctate staining for the myocytes, while polyclonal desmin (pD) stained in a filamentous pattern. Fibroblasts stained strongly with monoclonal anti-vimentin (Va), but did not stain with the desmin probes. Deep-etched immunogold studies confirmed at the ultrastructural level that monoclonal anti-desmin antibodies stain individual intermediate filaments in an intermittent pattern. Monoclonal (D₃) antibody stained the intermediate filaments heavily and continuously at the cell peripheries, while it stained intermittently in the cell body, similar to the Da monoclonal. Monoclonal anti-vimentin stained only intermediate filaments in fibroblasts. Our studies show a heterogeneity of staining within the cultured heart cells when various anti-desmin and anti-vimentin antibodies are used.     

Immunogold staining method for the light microscopic detection of leukocyte cell surface antigens with monoclonal antibodies: its application to the enumeration of lymphocyte subpopulations

Colloidal gold was used as a marker for the light microscopic detection of lymphocyte cell surface antigens with monoclonal antibodies. Suspensions of peripheral blood leukocytes were first incubated with monoclonal mouse antibodies and then with colloidal gold-labeled goat anti-mouse antibodies. The cells were fixed and cytocentrifuge preparations or smears were made. Granulocytes and monocytes were then labeled by the cytochemical staining of their endogenous peroxidase activity. Lymphocytes reacting with the monoclonal antibody had numerous dark granules around the surface membrane. With electron microscopy, these granules appeared as patches of gold particles. This immunogold staining method proved to be a reliable tool for the enumeration of T-lymphocyte subpopulations in peripheral blood. The results were almost identical to those obtained with immunofluorescence microscopy. The procedure can also be applied on small volumes of capillary blood. This constitutes a good microtechnique for the determination of lymphocyte subsets in children.     

Sensitive detection of immunogold-silver staining with darkfield and epi-polarization microscopy

We evaluated the contribution of darkfield and epi-polarization microscopy to the detection of leukocyte cell surface antigens with immunogold-silver staining (IGSS). Lymphocyte cell surface differentiation antigens were labeled with monoclonal antibodies and IGSS as described for brightfield microscopy. In darkfield and epi-polarization microscopy the labeling appeared as bright spots on a dark background. The sensitivity of detection was much higher than that of brightfield microscopy. Sixteenfold higher dilutions of the monoclonal antibody could be used to detect all cells expressing the antigen in the cell suspension. However, non-specific staining was also better visualized. The latter could be reduced to a level comparable to that of brightfield microscopy only by use of weaker labeling conditions. A 25% reduction of the silver enhancement time was necessary for this purpose. However, these weaker labeling conditions also reduced the intensity of the specific staining. Therefore, the efficiency of IGSS, as detected with darkfield and epi-polarization microscopy, was only fourfold greater than that found with brightfield microscopy or that of an immunofluorescence procedure. Especially in combination with transmitted light, to improve cell identification, epi-polarization microscopy is a reliable and sensitive method for detection of immunogold-silver-labeled cell surface antigens for diagnostic and research purposes.     

Immunogold labeling of keratin filaments in normal human epidermal cells with two anti-keratin monoclonal antibodies

We report on application of the highly sensitive and specific immunogold labeling method for ultrastructural investigation of keratin intermediate filament antigens in human epidermal cell suspensions. Triton X-100 pretreated cells proved accessible to the colloidal gold conjugate, thus enabling keratin filament bundles to be labeled. Anti-keratin KL1 and KL2 monoclonal antibodies were raised in mice after immunization with either human stratum corneum-isolated keratins or keratins extracted from human epidermal cells suspensions, respectively. Immunoelectron microscopy confirmed immunofluorescence and immunoperoxidase results of epidermal keratinocyte staining, and revealed two different antibody reactivity patterns: KL2 reacted with keratin filaments in keratinocytes of all epidermal layers, whereas antigen to KL1 was detected only on keratin of the suprabasal layers, not on the basal keratinocyte tonofilaments. The monoclonal antibody-recognized epitopes were specific for the keratin filaments. Vimentin-rich cells (melanocytes) were not stained in the same epidermal cell suspensions. Additionally, two distinct ultrastructural patterns of keratin filament epitope labeling were observed. KL1 and KL2 monoclonal antibodies react with two different antigenic determinants, depending on the stage of keratinocyte differentiation, and may therefore be used for immunohistochemical studies of various keratin-containing cells in normal and pathologic conditions.     

Immunofluorescent and immunogold replica studies of desmin distribution in cultured normal and cardiomyopathic hamster heart cells.

The architecture of desmin intermediate filament arrangements in cultured cardiomyocytes from heart of normal and cardiomyopathic hamsters was studied by immunofluorescent light microscopy and immunogold replica electron microscopy. Both polyclonal and monoclonal antidesmin antibodies were used in a biotin-streptavidin system. Immunofluorescent staining of normal and cardiomyopathic myocytes for desmin at 5 days in culture exhibited filamentous staining patterns with polyclonal antidesmin and a coarse punctate staining pattern with the monoclonal antibody. At 9 days in culture, most normal myocytes showed filamentous staining with the polyclonal antibody; many of the stained filaments were associated with Z lines. With the monoclonal antidesmin, these same cells exhibited a very fine 'spotty' staining pattern. These results suggest that the arrangements and immunoreactivities of intermediate filaments change during normal cardiac myocyte development. In cardiomyopathic cells, this pattern of rearrangement and immunoreactivity appears to be delayed or possibly nonexistent. The three-dimensional electron-microscopic observation of immunogold localization of desmin achieved by a deep-etching replica technique is made on both normal and cardiomyopathic cultured heart cells. Abnormalities of desmin filament arrangements in cardiomyopathic cells are confirmed.     

Light microscopical detection of leukocyte cell surface antigens with a one-nanometer gold probe.

The potential of ultrasmall gold particles for the light microscopical detection of leukocyte cell surface differentiation antigens was investigated. Suspensions and cytocentrifuge preparations of peripheral blood leukocytes were first incubated with monoclonal antibodies and then with goat antimouse antibodies coupled to colloidal gold particles of 1-nanometer diameter. Cytocentrifuge preparations were made from the cell suspensions. Silver enhancement was performed on all preparations. Then they were counterstained with May-Grünwald Giemsa and examined in light microscopy. The immunostaining appeared as fine dark granules on the surface membrane of the cells. Labeling conditions were determined which gave a dense specific immunostaining and a low background. High dilutions of the ultrasmall gold probe could be used to detect all antigen expressing cells in the samples. The labeling efficiency of the IGSS method with the 1 nanometer probe was comparable to that described earlier for 5 nanometer gold particles. Lymphocyte subsets enumerated with this method in normal peripheral blood were similar to those found with immunofluorescence microscopy. We concluded that one nanometer probes do not offer a major advantage in comparison with 5 nanometer probes for the study of cell surface antigens.     

Light microscopical detection of leukocyte cell surface antigens with a one-nanometer gold probe

Summary The potential of ultrasmall gold particles for the light microscopical detection of leukocyte cell surface differentiation antigens was investigated. Suspensions and cytocentrifuge preparations of peripheral blood leukocytes were first incubated with monoclonal antibodies and then with goat antimouse antibodies coupled to colloidal gold particles of 1-nanometer diameter. Cytocentrifuge preparations were made from the cell suspensions. Silver enhancement was performed on all preparations. Then they were counterstained with May-Grünwald Giemsa and examined in light microscopy. The immunostaining appeared as fine dark granules on the surface membrane of the cells. Labeling conditions were determined which gave a dense specific immunostaining and a low background. High dilutions of the ultrasmall gold probe could be used to detect all antigen expressing cells in the samples. The labeling efficiency of the IGSS method with the 1 nanometer probe was comparable to that described earlier for 5 nanometer gold particles. Lymphocyte subsets enumerated with this method in normal peripheral blood were similar to those found with immunofluorescence microscopy. We concluded that one nanometer probes do not offer a major advantage in comparison with 5 nanometer probes for the study of cell surface antigens.     

Lymphocyte subset responses to repeated submaximal exercise in men

The effects of repeated bouts of submaximal cycle ergometry exercise on changes in the percentage of peripheral blood T-lymphocytes, the T-helper/inducer and T-cytotoxic/suppressor subsets, and natural killer (NK) cells were studied in 18 healthy young men who had no history of regular exercise training. Subjects were matched on the basis of maximal O2 uptake and assigned randomly to exercise or control groups, with controls resting quietly during the exercise sessions. The percentage of peripheral blood mononuclear leukocytes that reacted with monoclonal antibodies specific for T-lymphocytes (CD3+ cells), the helper/inducer subset (CD4+ cells) and cytotoxic/suppressor subset (CD8+ cells) of T-lymphocytes, and cells with NK activity (Leu7+ cells) were enumerated by fluorescence-activated flow cytometry for samples obtained immediately before and after exercise on days 1, 3, and 5 of a 5-day exercise regimen. The results of this study were mixed with decreases in the percentage of T-lymphocytes before vs. after exercise on days 1 and 3 (P less than 0.001), a decrease in the percentage of T-helper/inducer cells before vs. after exercise on day 3 (P less than 0.05), no effect of exercise on the percentage of T-cytotoxic/suppressor cells, and a marked increase in the percentage of NK cells after exercise on days 1 (P less than 0.05) and 3 (P less than 0.01). The total number of recovered NK cells in the mononuclear leukocyte fraction of blood also increased significantly after exercise on days 1 (P less than 0.05) and 3 (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)     

Identification of cell subpopulations by dual-color surface immunofluorescence using biotinylated and unlabeled monoclonal antibodies

A new method of dual-color immunofluorescence is presented for analysis of surface antigen distribution among heterogeneous cell suspensions. It involves flow cytometric analysis of cells stained with a biotinylated first monoclonal antibody and/or with an unlabeled second monoclonal antibody. After addition of streptavidin-phycoerythrin and/or fluoresceinated goat antimouse immunoglobulin antibody, single-cell fluorescence intensities are measured and biparametric graphic representations are obtained, allowing one to determine the percentage of cells stained by each of the monoclonal antibodies or both. The validity of the method was assessed on human peripheral blood mononuclear cells by using three sets of two monoclonal antibodies: CD8 and CD5, CD3 and CD4, CD11 and HLA-DR. The results showed that dual staining did not induce significant quenching or competition between pairs of antibodies. The procedure is simple and sensitive. It requires only minute amounts of monoclonal antibodies. It is readily applicable to the screening of hybridoma supernatants and to the characterization of new antibodies to cell surface antigens with respect to well-defined markers.     

Identification of a nuclear protein component of interchromatin granules using a monoclonal antibody and immunogold electron microscopy

A monoclonal antibody, designated 780-3, has been generated which preferentially recognizes an antigenic component of interchromatin granules in human cells. By indirect immunofluorescence procedures, monoclonal antibody 780-3 produces a cell cycle-specific speckled nuclear staining pattern in adult human fibroblasts which is dramatically altered during metaphase. In contrast, transformed cells appear to express this antigen throughout the cell cycle in increased quantities. Immunogold electron microscopy revealed that the nuclear antigen is intimately associated with interchromatin granules in human cells. Analysis by immunoblot procedures showed that monoclonal antibody 780-3 recognizes two polypeptides of 105 and 41 kD. From these data, a possible nucleolar derivation of interchromatin granules is discussed. These studies demonstrate for the first time that monoclonal antibodies may be used in combination with immunogold electron microscopy to identify the ultrastructural location of nuclear antigens.     

Immunocytochemical localization of native chondroitin-sulfate in tissues and cultured cells using specific monoclonal antibody

Chondroitin-sulfate containing proteoglycan (CSPG) of the extracellular matrix (ECM) was visualized in chick tissues and cell cultures with a monoclonal antibody, CS-56. Cultured cells of various origins contained dense punctate layers of CSPG on both the substrate and the cell surface, as determined by immunofluorescent and immunogold staining. Under culture conditions the CSPG-containing matrix was usually excluded from stable cell-to-substrate focal contacts. The substrate-attached CSPG exhibited remarkable chemical stability but could be successfully removed by pronase or chondroitinases ABC and AC. Incubation of living cells with CS-56 antibodies resulted in the clustering of surface CSPG into patches, indicating that the surface-bound CSPG is free to move laterally along the plasma membrane. The unique properties of the CSPG-containing ECM revealed by CS-56 antibodies and their relationships to specific types of cell contacts are discussed.     

Comparison of lymphocyte subpopulations in arterial and venous blood of the rat

Lymphocyte subpopulation as well as other hematological properties were compared between arterial and venous bloods of Wistar-Imamichi rats. Lymphocyte subsets were defined with four monoclonal antibodies which were specific to the respective cell surface glycoproteins. Using these monoclonal antibodies, subsets of B lymphocytes, T lymphocytes, helper T lymphocytes, and suppressor and cytotoxic T lymphocytes in the peripheral lymphocytes were identified. The blood samples were taken from aorta abdominalis and venae cava caudalis. The population of these subsets were enumerated by a laser flow-cytometry system. The result showed that there was no significant difference in hematological properties between the arterial and venous blood except in leukocyte count and hemoglobin concentration. The difference in leukocyte counts was thought to depend mainly on the fluctuation of the lymphocyte counts. However, no significant difference was recognized in the proportion of positive cells to each monoclonal antibody. It was concluded that the difference in leukocyte counts found between the arterial and venous bloods of the Wistar-Imamichi rat did not produce any effects on the proportion of the subpopulation in the peripheral lymphocytes, and the lymphocyte subpopulations in both arterial and venous bloods were substantially equivalent to each other.     

Tissue distribution and ultrastructure of B lymphocytes reacting with the monoclonal antibody anti-Y29/55

The reactivity of normal tonsilar cells with the monoclonal antibody anti-Y29/55 is characterized at the tissue and ultrastructural cytological level. Using an indirect immuno-alkaline phosphatase method on frozen sections the antibody labels mantle zone and germinal center lymphocytes. This staining reaction is more generalized in B-lymphocyte areas than that obtained with antibodies to IgM and IgD. By indirect immunoperoxidase staining, as well as by an indirect rosetting procedure in cell suspensions, the reactive cell population were either small resting lymphocytes or activated lymphocytes corresponding to centrocytes, centroblasts, immunoblasts and plasmoblasts; some plasma cells were also labeled. These results characterize the monoclonal antibody anti-Y29/55 as a pan-B-marker antibody, useful for labeling resting and activated peripheral B-lymphocytes in frozen tissue sections and cell suspensions.     

Suppressor cells of the human NK activity: Characterization of the cells and mechanism of action

The surface marker characteristics and mechanism of action of small- to medium-sized NK suppressor lymphocytes, which can be found in both umbilical cord blood and adult peripheral blood, have been studied. Evidence suggestive of T-cell origin of the lymphocytes consisted of E-rosette formation, reactivity with OKT3 monoclonal antibody, and dot-like acid α-naphthyl acetate esterase (ANAE) staining pattern typical of T cells. Furthermore, no reactivity was seen with OKT6 and OKM1 monoclonal antibodies and the presence of intracytoplasmic immunoglobulin was excluded by indirect immunofluorescence microscopy, making the involvement of monocytes, B cells, and thymocytes less likely. As regards the mechanism of action, the role of prostaglandins was unlikely since indomethacin had no effect on the level of suppression. The role of soluble mediators was further examined by blocking cell secretion with monensin. In these experiments monensin treatment of the suppressor cells did not unwind suppression, suggesting that mechanisms other than secretion of suppressive factors were operative. The importance of cell-to-cell contact was demonstrated by the following observations: (i) A short contact of effector lymphocytes with suppressor lymphocytes, followed by their physical separation, resulted in decreased cytotoxic activity of the effector cells, (ii) Suppression could be mediated through Nuclepore filters, which allowed cell processes to pass through the filter, but not through filters which did not allow cell-to-cell contact. The suppressor cells were resistant to irradiation (2500 rad) and treatment with dexamethasone and puromycin. Viable cells were not needed, since paraformaldehyde-fixed suppressor cells could also mediate inhibition of K562 killing.     

Simultaneous cytometric analysis for the expression of cytoplasmic and surface antigens in activated T cells

A method of two-colour immunofluorescence staining has been developed to allow the simultaneous analysis of both surface and cytoplasmic antigens. This involves the use of direct fluorochrome antibody conjugates for cell-surface antigen staining, followed by cell permeabilization and the staining of cytoplasmic antigens with biotinylated antibodies and streptavidin-fluorochrome conjugates. Fluorochrome-antibody conjugates bound to cell-surface epitopes were found not to be affected by the subsequent permeabilisation and cytoplasmic staining. This method was used to examine the surface phenotype of T cells expressing a cytoplasmic antigen, STA. STA is a unique determinant detected in activated human T cells by the monoclonal antibody K-1-21, which also recognizes a cross-reactive conformation-dependent epitope on human free kappa light chains. Cytometric analysis showed that STA is found in both Leu 2a+ cytotoxic/suppressor T cells and Leu 3a+ helper/inducer T cells but is not induced in the Leu 15+ population which contains suppressor T cells. STA was also shown to be an activation antigen in murine T cells.     

Expression of epithelial antigens in primary cultures of normal human breast analysed with monoclonal antibodies

Abstract. Primary cultures of normal human breast were stained with monoclonal antibodies to see if antigens characteristic of luminal epithelial cells are retained in culture. Three monoclonal antibodies were used, LICR-LON-M8, LICR-LON-M18, and LICR-LON-M24, all specific for the cell surface of luminal epithelial as opposed to myoepithelial or stromal cells in the breast, and each staining a different subset of the epithelial cells in the intact tissue. Cultures were prepared from reduction mammoplasty samples by digestion with collagenase. The surface layer of cells was stained by immunofluorescence without fixation. (Cells underneath the surface layer were not accessible to this mode of staining). The antibodies stained patches of cells resembling flattened epithelium. These patches of cells cannot be distinguished by phase contrast microscopy without reference to the staining, in fact the boundaries of the cells are not usually resolved by phase contrast microscopy. Electron microscopy of sections through these cells show they are very flattened. They lie on top of the polygonal and elongated cells that dominate the phase contrast image. Two of the antibodies, M8 and M24, stain subsets of these epithelial-like cells at all stages of culture. The third antibody, Ml8, stains such cells initially, but after the first few days staining is predominantly found on the polygonal and elongated cells, then this also gradually disappears. It is possible that the cells stained by antibody Ml8 are converting from the epithelial-like morphology to the cuboidal and elongated morphology. Many cells are not stained by any of the antibodies, so appear either to by myoepithelial in origin or to have lost their luminal epithelial surface antigens at an early stage. This analysis draws attention to the variety of cell types in these cultures and the limitations of phase contrast microscopy as a means of analysing them.