Immunohistologic analysis of a human pulmonary alveolar macrophage antigen

Co-expression of endothelial cell and macrophage antigens in Kaposi's sarcoma cells

The histopathogenesis of Kaposi's sarcoma (KS) was investigated using immunocytochemistry in 12 skin biopsies obtained from two AIDS patients, nine patients with the classic form, and one organ-transplant patient. KS cells revealed a peculiar antigenic profile, being characterized by co-expression of endothelial and macrophage markers. KS cells were stained for von Willebrand factor (vWF); for vascular endothelial (VE) cadherin, an endothelial specific adhesion molecule; and for PECAM/CD31. In addition, they expressed the macrophage antigens PAM-1, CD68, and CD14, and were positive for vitronectin receptor and alpha-1,5,6/beta-1 integrins. KS cells were weakly stained for ICAM-1 in 6 of 12 cases and were negative for VCAM-1 and E-selectin.

Expression and modulation of a mononuclear phagocyte differentiation antigen (PAM-1) during in vitro maturation of peripheral blood monocytes

Human macrophages obtained by in vitro maturation of peripheral blood monocytes express a surface antigen, PAM-1, recognized by a monoclonal antibody and typical of pulmonary alveolar and tissue macrophages. PAM-1, undetectable in freshly isolated peripheral blood monocytes, was expressed in monocyte-derived macrophages after 3 days of in vitro adherent culture and was maximal after 14-15 days (50%-60% of positive cells). Similar levels of PAM-1 positivity were observed in non-adherent monocyte-derived macrophages suggesting that cell adhesion was not a critical requisite for the expression of this antigen. Bacterial lipopolysaccharide and a monocyte chemotactic protein preparation respectively suppressed and upregulated PAM-1 expression in monocyte-derived macrophages. In contrast, interferon-gamma, although enhancing the levels of class II HLA-DR antigen in monocyte-derived macrophages, did not influence the kinetics of appearance and the levels of PAM-1 in these cells. Thus, expression of PAM-1, which is restricted to certain stages of the monocyte-macrophage differentiation pathway, is also differentially modulated by activation signals, which can be present in the micro-environment of inflammed tissues.

Macrophages and interdigitating reticulum cells in normal thymus and in thymoma: an immunohistochemical study

The distribution and immunophenotype of macrophages and interdigitating reticulum cells were investigated on frozen sections of seven normal thymuses and 10 thymomas. In normal thymus, macrophages were mainly located in the cortex, were markedly PAM-1+/MAC+, weakly Leu-M3+ (CD14), T4+ (CD4), T9+ and OKM-1+ (CD11b). Interdigitating reticulum cells were mainly located in the medulla and were pan-Leu+ (CD45), T4+(CD4+), HLA-DR+; furthermore, they were also often TAC+ (CD25) and T9+. Thymomas were composed of cytokeratin-containing epithelial cells admixed with variable proportions of T6+ (CD1a) lymphocytes. As defined by the histological features two thymomas were lymphocyte-rich, five were mixed type and three were epithelial-rich; eight thymomas were mainly composed of cortical epithelial cells and two were composed of spindle epithelial cells suggesting a medullary origin. In all cases, thymoma-associated macrophages were markedly PAM-1+/MAC+; they were numerous, and regularly distributed throughout the tumour. The density of macrophages per unit area was similar to that of the normal thymus, and was not influenced by the histological type or by the lymphocyte content of the tumour. Interdigitating reticulum cells were few and were confined to the areas of medullary differentiation.

Isolation and antigenic identification of hamster lung interstitial macrophages

Lung interstitial macrophages (IMs) are a large, distinctive population of cells with important proliferative capacities. Characterization of their role in health and disease has been hampered by inadequate methods to separate interstitial from residual alveolar macrophages (AMs) in preparations of individual mononuclear cells from lung tissue. In this study, a specific cell-surface antigen (HAM1) present on more than 90% of hamster AMs, but not expressed by hamster IMs, was used to distinguish these populations. After collagenase digestion of lung tissue slices from exhaustively lavaged and perfused hamster lungs, mononuclear phagocytes were isolated by density gradient centrifugation. The mean yield of lung digest macrophages (3.9 +/- 1.9 (SD) x 10(6] was comparable to the yield of lavaged AMs (4.2 +/- 1.9 x 10(6]. The proliferative capacity of lavaged AMs, blood monocytes, and lung digest macrophages was compared using a soft-agar colony-forming unit (CFU) assay. Both lung digest macrophages and blood monocytes had significantly more CFUs (68.7 +/- 2.6 and 53.5 +/- 8.4 CFU/10(3) cells [mean +/- SEM], respectively) than did AMs (16.5 +/- 1.7) (p less than 0.01). To further define the composition of the lung digest macrophage population, flow cytometric analysis of fixed cells from six experiments was performed using a mouse monoclonal antibody specific for the HAM1 antigen found only on AMs. The lung digest macrophage population consisted of both antigen-negative IMs (78.2% +/- 3.7% [SEM]; n = 6) and antigen-positive, residual AMs (21.8% +/- 3.7%). Morphometric counts confirmed that substantial numbers of AMs are left behind after lavage and contribute to macrophages obtained from lung tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

Four monoclonal antibodies, AMH-1, -2, -3, and -4, give varied reactivities with monocytes, alveolar macrophages, and epithelioid-cell granulomas

Four monoclonal antibodies, termed AMH-1, AMH-2, AMH-3, and AMH-4, raised against human lung macrophages in bronchoalveolar lavaged fluid, alveolar spaces, and interstitia of lung tissue are described. The antibodies were produced according to hybridoma technique by immunizing mice with bronchoalveolar lavaged cells. All four monoclonal antibodies reacted with macrophages in bronchoalveolar lavaged fluid and alveolar spaces by immunohistochemical staining and flow cytometric analysis, but they gave different reactivity patterns with the monocyte-macrophage lineage. AMH-1 did not react with peripheral blood monocytes, peritoneal macrophages, or pulmonary interstitial macrophages. Although AMH-2 reacted weakly with blood monocytes and with some of the pulmonary interstitial macrophages, it did not react with peritoneal macrophages. AMH-3 did not show reactivities with either blood monocytes or peritoneal macrophages but was positive for most of the pulmonary interstitial macrophages. AMH-4 was reactive with cells from the monocyte-macrophage lineage. There was a correlation between the reactivity patterns of all four antibodies to macrophages in bronchoalveolar lavaged fluid and the patients' smoking habits. Most significantly, epithelioid cells of lung granulomas obtained from patients with sarcoidosis and hypersensitivity pneumonitis were negative for AMH-1 but were strongly stained by AMH-2, AMH-3, and AMH-4. Differences among the four antibodies in their reactivities with macrophages and granulomas in lungs indicate that lung macrophages contain heterogeneous populations which are in various states of differentiation and maturation and that the epithelioid cells and lung macrophages share the same membrane antigens. Therefore, these antibodies would be useful reagents for investigating the subpopulations and functions of macrophages in lungs and for clarifying the pathogenesis of granulomatous lung diseases.

Defective chemotaxis of human alveolar macrophages

Human pulmonary alveolar macrophages (PAM) from normal subjects, unlike peripheral blood monocytes (PBM), are unable to migrate in response to various chemoattractants, such as C5a,f-Met-Leu-Phe (fMLP) and phorbol myristate acetate (PMA). Inflammatory PAM obtained from sarcoid patients also failed to exhibit a chemotactic response. Binding studies using [3H]PDBU demonstrate high affinity receptors for phorbol esters on PAM surface, in a comparable amount (1.5-2.4 X 10(6) receptors/cell) to PBM (8-15 X 10(5) receptors/cell). Moreover, PAM were comparable to PBM in terms of superoxide anion (O2-) release in response to PMA. Therefore, the defective locomotory response of PAM cannot be accounted for by lack of chemoattractant receptors, at least for phorbol esters. Worthy of note, PMA receptors on PAM are able to transduce activating signals for O2- generation. These findings show that competence for chemotaxis is heterogeneously distributed among mononuclear phagocytes.

Immunohistochemical heterogeneity of macrophage subpopulations in human lymphoid tissues

The mononuclear phagocytic system is composed of cells which display a marked immunohistological heterogeneity. In the present study we have investigated the immunohistochemical and enzymatic features of macrophages and accessory cells present in human lymph nodes and spleen and, as control tissues, in thymus, liver, skin and heart. Our investigation has demonstrated that macrophages present in germinal centres display an immunophenotype different from that of macrophages populating T-dependent areas. Furthermore, cells lining lymph node sinuses and splenic sinusoids express endothelial and macrophage markers, and are able to modulate their immunophenotype according to different reactive conditions. These data suggest, on immunohistochemical grounds, that macrophages populating B- and T-dependent areas as well as sinuses of human peripheral lymphoid tissues, may modulate their immunophenotype according to environmental and antigenic influences.

The detection of two surface antigens on human lung macrophages using monoclonal antibodies

Monoclonal antibodies (McAb), designated AMH1 (IgM, lambda) and AMH2 (IgG1, Kappa), against specific surface antigens of human lung macrophages were produced by the fusion of the NS-1 plasmacytoma cell line with spleen cells from BALB/c mice immunized with bronchoalveolar lavaged (BAL) cells obtained from selected smoking subjects. The screening and characterization of these McAb were carried out employing cellular radioimmunoassay, flow cytofluorography, and immunohistochemical methods. These two antibodies specifically reacted with macrophages in the alveolar spaces and BAL fluids. AMH1 did not react with peripheral blood cells including freshly separated monocytes, cultured monocytes, lymphocytes, granulocytes, and platelets. In addition, AMH1 did not react with peritoneal exudate cells or pleural exudate cells. On the other hand AMH2 showed the dull-positive reaction with some monocytes and pleural exudate cells among above-mentioned cells. These two McAb seemed to detect cell surface antigens that are expressed by highly differentiated or mature macrophages compared to OKM1. These antibodies will allow not only better characterization of immune cells but also assessment of maturity of lung macrophages.

Immunohistology of adenolymphoma (Warthin's tumour): evidence for a role of vascularization in the organization of the lympho-epithelial structure

The epithelial, vascular and lymphoid components present in two cases of adenolymphoma (Warthin's tumour) were characterized by immunohistochemistry on frozen sections. Epithelial cells were positive for cytokeratin and keratin and were in close contact with numerous factor VIII related antigen-positive capillary vessels, running parallel to the epithelial basement membrane. The capillary vessels were in communication with high endothelial post-capillary venules which were often lined by HLA-DR-positive endothelial cells. The lymphoid tissue was organized in B-cell and T-cell areas. The B-cell areas consisted of B4+/To15+ B-lymphocytes admixed with DRC-1-positive follicular dendritic reticulum cells. The T-cell areas were mainly populated by T11+/T3+/T4+ lymphocytes admixed with some S-100+/HLA-DR+ interdigitating reticulum cells. Plasma cells and T8+ lymphocytes were more numerous in the proximity of the epithelium. Leu-M3+/PAM-1+ macrophages were scattered singly in the T-cell areas or were arranged in sinus-like structures around the epithelial cysts. The epithelial basement membrane, the vascular membrane and the fibrillar reticular stroma of the lymphoid tissue were immunoreactive for laminin and type IV collagen. The possibility is discussed that the accumulation of lymphoid tissue in Warthin's tumour is modulated by the epithelial cells, perhaps through their ability to organize a peculiar pattern of vascularization.

Evidence for neoplastic cell differentiation in mediastinal T lymphoblastic lymphoma

Immunostaining of frozen sections from a mediastinal T lymphoblastic lymphoma (T-LL) revealed the existence of two neoplastic cell populations characterized by different degrees of maturation. Several large nodules of 3A1+/T11+/T9+ T6-/T4-/T8-/T3- lymphoid cells, resembling normal early thymocytes, were surrounded by 3A1+/T11+/T9+/T6+/T4+/T8+/T3- cells resembling normal cortical thymocytes. The junctional area between early and cortical lymphocytes was occupied by numerous Leu-M3+/PAM-1+/DR+ reticular macrophages which were also characterized by J5 reactivity. Cytokeratin+/keratin+ epithelial cells were absent. Immunostaining of paraffin sections and of cytocentrifuge smears obtained from tumour cell suspensions revealed that a consistent percentage (8%) of neoplastic lymphoblasts were S-100+. Our findings are consistent with a cortical T-LL presenting areas of dedifferentiated cells or, alternatively, with an early T-LL whose cells were able to differentiate into cortical thymocytes, perhaps through the interaction with a specialized subset of J5+ macrophages.

Lectin I of Ulex europaeus as a marker for a subset of histiocytic tumours of the lymph node

We describe four lymph node based tumours in which numerous neoplastic cells and some mitotic figures were characterized by staining affinity for Lectin I of Ulex europaeus (UEA-I). The patients had no vascular or epithelial tumours and presented symptoms suggestive of a systemic lymphoproliferative disease. Histologically, the tumours were composed of large, cohesive, cells which were mainly located in the paracortex. UEA-I reactivity was more evident in the Golgi area and was present in large mononucleated cells often arranged to delimit vascular-like spaces. The neoplastic cells were weakly muramidase-positive in one case, and were ANAE+/AP+ in two other cases. Large dots of UEA-I reactivity were detected in S-100+/muramidase-negative Langerhans-like cells present in one case of Letterer-Siwe disease. UEA-I staining was consistently negative in 20 cases of B cell- or T cell lymphoma and in 9 other cases of histiocytic lymphoma. It is suggested that UEA-I+ tumours of the lymph nodes are part of a distinct subset of histiocytic malignancies whose neoplastic cells present some morphological and phenotypic properties normally associated with endothelial cells.