Cytochemistry of normal lymphocyte subsets defined by monoclonal antibodies and immunocolloidal gold

Methods of Simultaneous Visualization of Cytoplasmic Enzyme Reactivity and Cell Surface Antigens (by Cytochemistry Combined with Immunocytochemistry) in Individual Hematopoietic and Lymphoid Cells

Enzyme cytochemistry alone, and more recently, immunocytohistochemistry have been satisfactorily used by hematologists and hematopathologists for the study, diagnosis and classification of human hematological and lymphoproliferative disorders. To enhance the potential of these techniques, the possibility of combining immunocytohistochemical techniques with enzyme cytohistochemistry with simultaneous visualization of both reaction products has been examined by some investigators. This approach has been applied to normal, reactive and neoplastic material using mainly cell suspensions and frozen sections, with the aim of improving cell identification in specimens containing different cell types, of determining the cytochemical profiles of well-defined lymphocyte subpopulations and of establishing the cell surface phe-notypes of cells that are positive for certain enzymes. In this paper, published reports on this subject are reviewed and compared with the experience of our study group.

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.

Immunogold staining in bone marrow aspirate for the study of surface markers in acute lymphoblastic leukemia

The diagnostic value of phenotyping acute lymphoblastic leukemia (ALL) of childhood using the immunogold staining method (IGS) was assessed in 34 consecutive new ALL patients seen at Children's Hospital of Pittsburgh during a 14-month period. IGS proved to have considerable value in the diagnosis and classification of ALL. It allowed a sharp and clear identification of surface antigens, documented surface antigen heterogeneity in normal and abnormal cells, and provided a permanent record. The combination with cytochemistries allowed further cytoplasmic identification and correlation. This method does not require sophisticated equipment and can be performed in any laboratory, thus enabling results from different institutions to be more readily compared.

Direct immunogold staining technique based on monoclonal antibodies: an immediate approach to the immunostaining of lymphocytes

The report provides a procedure for labelling of monoclonal antibodies (moab's) with colloidal gold particles (mean diameter 30 or 40 nm). This procedure was exemplified for the moab's BL-T2, BL-Ig-L/1, and BL-Ia/1, which label mature T (and some populations of B) lymphocytes, B lymphocytes, and HLA class II antigen bearing lymphocytes, respectively. Each moab was characterized by an individual pH optimum for stabilization of the gold sol. The pH optima were +/- 5 (BL-T2), +/- 7 (BL-Ia/1), and +/- 9 (BL-Ig-L/1). The immunogold staining reagents were used for a direct immunostaining protocol of lymphocytes, which needs less than 100 min. The intensity of this direct immunolabelling was comparable with this one resulting from the indirect IGS. Furthermore, the comparison of the direct IGS with the immunofluorescence technique does not revealed any significant difference in the mean cell counts. The presented immunolabelling method offers a straight cell tagging, which can be advantageously used for a double staining procedure.

Characterization of lymphocyte subpopulations in human cord blood using the immunogold staining technique

Lymphocyte subpopulations in human cord blood have been examined using monoclonal antibodies, visualized with immunogold. The proportions of T11, T4, T8, and B1 cells in cord blood are very similar to values in adult peripheral blood. Some evidence of lymphocyte immaturity in cord blood is suggested by the presence of 12% CALLA-positive cells and the sum of T4 and T8 cells significantly exceeding the number of T11 cells; however, there were no TdT-positive cells. The presence of CALLA-positive lymphocytes in normal cord blood should be borne in mind when investigating blood smears from neonates for congenital leukemia.

Acid hydrolases in B-chronic lymphocytic leukemia (B-CLL): a comparison with normal peripheral B lymphocytes and normal B-cell subset with the phenotype of B-leukaemic cells

The acid phosphatase (AP), beta-glucuronidase (BG), and alpha-naphthyl-acetate esterase (ANAE) distribution and the morphology of stage 0 B-CLL lymphocytes were studied. The results were compared with the same hydrolase equipment and morphology of normal B-cell populations showing the B-CLL-like phenotype, and thus regardable as the possible counterpart of leukaemic cells. The functional and structural characters of the former were strikingly different from those of the latter. In fact the normal B-cell population with B-CLL-like phenotype showed an homogeneous enzyme pattern with predominant ANAE and a strictly lymphocytic cell morphology. In contrast, the leukaemic cells showed various and unrelated morphological and cytochemical features, thus forming apparent subgroups of B-CLL. The development of an irregular "switch on" mechanism in the blocked malignant cell clone, may account for these functional and structural maturation discrepancies. Moreover, the fact that in the leukaemic cells ANAE activity could be demonstrated only after the appearance of the other hydrolases, makes it a marker of functionally differentiated B lymphocytes.

Immunogold staining: an alternative method for lymphocyte subset enumeration. Comparison with immunofluorescence microscopy and flow cytometry

An immunogold staining procedure for light microscopic enumeration of peripheral blood lymphocyte subsets defined by monoclonal antibodies (OKT3, OKT4, OKT8, OKIa1, Leu 1, Leu 4, Leu 2a, Leu 3a, Leu 10, Leu 12, B1) is described. It uses colloidal gold-labeled goat anti-mouse Ig (GAM G40 and GAM G30) as second layer and a methyl-green pyronin counterstain. Performed on small volumes of blood without sophisticated laboratory equipment, this method allows accurate cell type recognition and permanent records, essential for longitudinal observations. By enumerating the gold particles on positively labeled cells, it was shown that the staining reactivity depended on the monoclonal antibody used. Lymphocytes reacting with OKT8 or OKIa1 or B1 exhibited the strongest labeling whereas OKT4+ cells were weakly labeled. When compared with flow cytometry analysis in healthy subjects, the accuracy, precision and sensitivity of both methods were very similar. Similarly, a close correlation (97%) was found between immunogold staining and immunofluorescence microscopy in 35 patients with various diseases suggesting that immunogold staining may be useful in a clinical context.

beta-D-N-acetylglucosaminidase, a new cytochemical marker of human lymphocyte subpopulations

beta-D-N-acetylglucosaminidase staining characteristics of rosetted or non-rosetted normal and malignant lymphoid cells were compared with those observed after nonspecific esterase and acid phosphatase staining. With the three cytochemical techniques a similar staining pattern was observed in T cells (E-rosettes), their subpopulations T mu and T gamma, B cells and the non-T, non-B cells, as well as in the T cell populations defined with the monoclonal antibodies OKT3,4 and 8. T mu cells mostly displayed a "dot-like" reaction, T gamma and the non-T, non-B cells a "fine to heavy granular" reaction, while most B cells were negative. OKT4 and OKT8 positive lymphocytes showed for the larger part a dot-like staining pattern, however, the frequency of cells with a granular pattern was distinctly higher in the OKT8, than in the OKT4 positive cells. E(+)mIg(-) and E(-)mIg(-) A.L.L. blasts stained either with a dot-like or granular pattern or failed to react when stained cytochemically for beta-D-N-acetylglucosaminidase, nonspecific esterase and acid phosphatase activity. Only in a few instances a discrepancy was observed between the types of staining for esterase and acid phosphatase on one hand and those for beta-D-N-acetylglucosaminidase on the other.

Method for the simultaneous labelling of terminal deoxynucleotidyl transferase (TdT) and membrane antigens

A method for the simultaneous labelling of terminal deoxynucleotidyl transferase (TdT) and membrane antigens is described. TdT is visualised in the cell nucleus with the peroxidase-antiperoxidase (PAP) method, and the immunogold method is used in combination with monoclonal antibodies against membrane antigens. The morphology of the labelled cells is well preserved for analysis by light microscopy and the preparations obtained can be kept permanently. This method is useful for the analysis of mixed cell proliferations, particularly in leukaemias.

Simultaneous demonstration of membrane antigens and cytochemistry at ultrastructural level: a study with the immunogold method, acid phosphatase and myeloperoxidase

We describe a method for electron microscopy that combines myeloperoxidase or acid phosphatase cytochemistry with the labelling of cell surface antigens with monoclonal antibodies and colloidal gold. This technique was tested in samples of normal mononuclear cells, leukaemic T cells with a mature or immature phenotype and an acute myeloid leukaemia. This method allows the demonstration at a single cell level of ultrastructural morphology, cytochemical reaction and the presence of a membrane antigen. It will improve further the analytic power of electron microscopy in the characterization of leukaemic cells particularly in cases of mixed leukaemias and in the study of normal haemopoietic differentiation with monoclonal antibodies.