Scanning immunoelectron microscopy of hairy cell leukemia

Detection of allergens adsorbed to ambient air particles collected in four European cities

Air pollution has been implicated as one of the factors responsible for the increased incidence of allergic diseases observed in recent years. High concentrations of air pollutants may promote airway sensitization by acting as adjuvants. Ambient particles as carriers of adsorbed allergens are, therefore, of special interest since they may act as mediators of inflammatory as well as allergic responses. Ambient air particles from four cities in Europe were collected, in three different seasons, to examine the variation of allergens and their possible binding to the pollution particles. The particle fraction, PM10, was collected on polycarbonate filters using a low-volume sampling regime. The presence of pollen allergens, latex and beta-glucans was investigated using an immunogold labelling method directly on the collection filters. Scanning electron microscopy revealed mainly the classical carbon particles and aggregates determined to originate from vehicle exhaust. The immunogold labelling visualised in the backscatter electron imaging mode, showed that allergens from pollens, latex and also beta-glucans were bound to and, hence, transported by the combustion particles in ambient air. Thus, combustion particles in ambient air are carriers of allergens and act as depots of allergens inhaled into the airways.

Scanning and transmission electron microscopy of clonal peripheral blood lymphocytes in low grade non-Hodgkin's B-cell lymphomas with predominant splenomegaly

Peripheral blood mononuclear cells (PBLs) from 14 patients with low grade non-Hodgkin's B-cell lymphomas with predominant splenomegaly were studied by means of scanning (SEM) and transmission electron microscopy (TEM). All patients had peripheral blood and bone marrow involvement, the absence of lymphoadenopathy, and, except in one case, immunophenotypic features of a malignant proliferation of mature spleen B-cells arising from outside the germinal center, but not consistent with CLL or HCL. Several distinctive cytological features were observed in PBLs of the different subgroups. The SEM surface features of PBLs in patients with intermediate differentiation lymphocytic lymphoma (IDL) (five cases), lymphoplasmacytoid immunocytoma (LP-IC) (two cases), and mixed small and large cells malignant lymphoma (one case) were characterized by the presence of numerous well-developed microvilli. Some distinctive TEM ultrastructural features were also seen in the different cases. In the two cases of splenic lymphoma with villous lymphocytes (SLVL), SEM revealed large and elongated surface microvilli generally arising from two or three poles of the cells. This surface morphology, confirmed by TEM analysis, may be pathognomonic of this disease. Four additional cases, tentatively classified as small lymphocytic lymphoma on the basis of immunophenotypic data, were extremely heterogeneous at both SEM and TEM analysis. The ultrastructural features revealed by SEM and TEM may be useful for the more precise characterization of this heterogeneous group of diseases, which is generally difficult to define even when immunophenotypic and molecular approaches are used.

Backscatter electron imaging of double immunogold labeled erythrocytes using two primary monoclonal IgM antibodies

The majority of mouse monoclonal antibodies reacting with blood group epitopes on erythrocytes are of the IgM class, have equal light chain type, and are available as culture supernatants only. To study the interrelationship of the blood group antigens, a method is presented which allows double labeling applying two unconjugated monoclonal antibodies of the same class and species. The method comprises two indirect, sequential labelings using mouse IgM anti-A and anti-H as primary antibodies and two goat anti-mouse IgM conjugated to 30 and 20 nm colloidal gold particles as secondary antibodies. After labeling for the first antigen, free binding sites on the primary antibody are blocked by incubation with an unconjugated goat anti-mouse antibody. The free anti-species on the secondary antibody, conjugated to 30 nm gold particles, are inactivated by silver enhancement. The silver enhancement also enlarges the gold particle for optimal discrimination between the two particle sizes, which are chosen accordingly. Semiquantitations of double labeled cells from subgroup A2 and A3 were found to be in good agreement with the counts of the corresponding single labelings as well as between experiments, irrespective of which of the two antibodies was applied in the first labeling sequence. The results were in accordance with a reciprocal but nonlinear relationship between the A and H antigens and suggest different affinities of the two antibodies for the epitopes in the subgroups investigated, indicating different biochemistry of the antigen determinants.

Immunogold labelling of leukemic hairy cells with the B-ly7 monoclonal antibody: an SEM and TEM study

Two cases of hairy cell leukemia have been studied by immuno-TEM and immuno-SEM after immunogold labelling of the cell surface antigen recognized by the B-ly7 monoclonal antibody. Most hairy cells appeared significantly labeled, although the density of the expression of the antigen, as demonstrated by immunogold labelling, seems variable from cell to cell. Moreover, some cells with the morphology of hairy cells and which could not be identified as monocytes were not labeled. Labelling for the antigen identified by the B-ly7 mAb does not seem to correlate with the presence of ribosome lamellae complexes which were present only in one of the two cases studied. Rare lymphocytes of unidentified lineage were labeled. Monocytes were significantly absent from the samples of peripheral blood of the two patients studied. In one normal control sample, monocytes were observed unlabelled. The results are discussed in reference to the pathogenesis of hairy cell leukemia, its surprisingly low mitotic rate, and its distinct response to chemotherapy.

Expression of A antigens on erythrocytes of weak blood group A subgroups

Scanning immune electron microscopy using a monoclonal anti-A antibody which reacts with all type A oligosaccharide chains revealed A antigens on less than 5% of Am and Ael cells, some of which showed extremely strong labelling. This explains why Am and Ael cells can absorb significant amounts of anti-A without being agglutinated. A3 may be a heterogeneous subgroup, since A antigens were found on 82 and 58%, respectively, of the cells of 2 A3 individuals. A antigens were found on 75% or more of Ax cells. In many weak A individuals A-positive cells are apparently best detected if an anti-A is used which reacts strongly with other A oligosaccharide chains than type 2. From hyperimmune pregnancy sera Ax, Am and Ael erythrocytes absorbed antibodies which seemed to have other fine specificities than those absorbed by A2 cells. We conclude that weak subgroups of A may deviate from A2 both by number of erythrocytes expressing A antigens and the biochemical nature of the antigens.

Silver enhancement of gold probes (5-40 nm): single and double labeling of antigenic sites on cell surfaces imaged with backscattered electrons

Silver enhancement of immunogold-labeled cells was carried out to increase the applicability of colloidal gold probes for visualization in the backscatter electron imaging (BEI) mode of a scanning electron microscope. Optimum conditions were established for single particle discrimination and differential counting of labeling density at low magnifications. Red blood cells double-labeled with 15 + 40 nm and 5 + 20 nm gold probes were silver-enhanced for 6 min and 20 min, respectively, at which times both pairs of labels increased to about 25 + 50 nm. The gold probes still appeared spherical after enhancement and were easily discriminated. Cells were also single-labeled with the above probes and enhanced accordingly. The present method enables visualization of individual particles of any probe size, labeling one, or simultaneously two, antigenic sites on cell surfaces. The silver enhancement procedure thereby allows cells to be labeled with small probes with increased labeling efficiency.

A study of immunogold-labelled blood group A erythrocytes in the scanning electron microscope

This report presents binding patterns on A1, A2, A3, Ax and Ae1 erythrocytes of a monoclonal anti-A (A 003) antibody which reacts predominantly with difucosylated A oligosaccharides, visualized with colloidal gold particles in the backscattered electron imaging mode of a scanning electron microscope. A relatively weak labelling was found on most A1 cells, while the labelling in subgroups A2, A3 and especially Ax appeared relatively stronger. Very few Ae1 cells were labelled. The results emphasize the qualitative uniqueness of A1 and suggest that many Ax cells have high proportions of difucosylated A oligosaccharides. Labelling variations were found between different A3 and Ax traits, and in all subgroups between cells and even between different parts of the cells. No immunolabelling differences were found in relation to secretor status.

Immunohistochemical evaluation of bone marrow involvement in hairy cell leukemia during interferon therapy

Bone marrow biopsies from 7 patients afflicted with hairy cell leukemia were studied with a panel of monoclonal antibodies at different intervals during alpha recombinant interferon therapy. Monoclonal antibodies Dako-LC and F 8.11.13 were used because they are highly reactive with hairy cells, and 82H3 and LeuM 1 were also utilized to identify respectively the residual hemopoietic and myeloid tissue. All antibodies are reactive on sections of formalin-fixed, paraffin-embedded biopsy material. Before therapy a uniform hairy cell infiltrate was present and very little tissue was visible even after immunohistochemical staining. During therapy, identification of hairy cells in routine biopsies was difficult, since they were mixed with normal cells and the bone marrow was generally hypoplastic. Immunohistochemical stains seem to allow better identification of hairy cells and a more precise estimate of the degree of repopulation by normal bone marrow cells. It was evident, especially after immunocytochemical analysis, that interferon drastically reduced the extent of the infiltrate and allowed recovery of normal hemopoiesis, but did not produce complete remissions.