The origin of blood monocytes and macrophages. A review

Some recent advances on the study and understanding of the functional design of the avian lung: morphological and morphometric perspectives

The small highly aerobic avian species have morphometrically superior lungs while the large flightless ones have less well-refined lungs. Two parabronchial systems, i.e. the paleopulmo and neopulmo, occur in the lungs of relatively advanced birds. Although their evolution and development are not clear, understanding their presence is physiologically important particularly since the air- and blood flow patterns in them are different. Geometrically, the bulk air flow in the parabronchial lumen, i.e. in the longitudinal direction, and the flow of deoxygenated blood from the periphery, i.e. in a centripetal direction, are perpendicularly arranged to produce a cross-current relationship. Functionally, the blood capillaries in the avian lung constitute a multicapillary serial arterialization system. The amount of oxygen and carbon dioxide exchanged arises from many modest transactions that occur where air- and blood capillaries interface along the parabronchial lengths, an additive process that greatly enhances the respiratory efficiency. In some species of birds, an epithelial tumescence occurs at the terminal part of the extrapulmonary primary bronchi (EPPB). The swelling narrows the EPPB, conceivably allowing the shunting of inspired air across the openings of the medioventral secondary bronchi, i.e. inspiratory aerodynamic valving. The defence stratagems in the avian lung differ from those of mammals: fewer surface (free) macrophages (SMs) occur, the epithelial cells that line the atria and infundibula are phagocytic, a large population of subepithelial macrophages is present and pulmonary intravascular macrophages exist. This complex defence inventory may explain the paucity of SMs in the avian lung.

Presence of pulmonary intravascular macrophages in the equine lung: some structuro-functional properties

The pulmonary intravascular macrophages (PIMs) have been described in several species of animals. This study demonstrates for the first time that the equine lung has PIMs as resident phagocytes in its microvasculature. Their salient features such as globular surface coat, structures of the endocytic pathway, and related cell organelles closely resemble those of the calf, goat, and sheep. The exquisite organization of the coat globules in the form of a linear chain was structurally similar to the lipolytic lipase and the heparin-sensitive globular coat from PIMs of calf, goat, and sheep. Monastral blue (MB) when employed as a tracer to assess the phagocytic properties of equine PIMs induced similar modification of the globules of the coat into lipid droplets, reminiscent of neutral lipids. Lipids droplets (modified coat globules) were delivered into acid phosphatase-positive endosomes and lysosomes. Concurrently, the unaltered globules of the coat, probably internalized via fluid-phase constitutive pinocytoses, followed a different endocytic pathway. Large-scale platelet uptake by the PIMs was observed with thrombocytopenia in MB-treated ponies. The possible significance of hypothetical LDL-coat and the endocytic organelles as equivalents of synthetic apparatus of vasoactive lipids in the PIMs of horse needs to be assessed in future studies.

Immune response: self-foreignness

The classical basic concept of the immune system as a defence system per se and immunological surveillance against neoplasia have never been satisfactorily verified experimentally. The reason for this lies in the historic development of immunology in terms of observations of infectious disease and the interpretation of those observations. Thus, based on a complete lack of understanding of immune events, immunization procedures were developed by Pasteur and his contemporaries. The success of some of these immunization methods, influenced by culture and philosophical thoughts, and based on prima facie evidence allowed the next conceptual step to be taken, culminating in the immune surveillance hypothesis. Central to this hypothesis is selection and tolerance to self-antigens. However, immune reactions to self-antigens are evident and clonal selection is not viable because the number of clones required increases as the frequency of chance of a cell belonging to a particular clone decreases. Also, circadian rhythms in the immune response have not been taken into account. In addition, the problems of haemocytopoiesis have not been addressed, in that it is possible for B-lymphocytes to become terminal macrophages and T-lymphocytes to become mast cells, eosinophils and/or basophils constituting 'dead end' cells in an immune response. The initiation of the immune response begins with a tissue-specific T-lymphocyte being stimulated and undergoes replication. This gives rise to a dual functional helper/suppressor cell and a B-lymphocyte. These basic concepts explain the necessity for auto-reactive lymphocytes, that is the autologous mixed lymphocyte reaction (AMR). The AMR is a natural consequence of having tissue-specific lymphocytes to monitor plasma membrane aberrations.

Pulmonary intravascular macrophages in domestic animal species: review of structural and functional properties

In dogs, laboratory animals, and man, the clearance of bacteria and particulates from blood occurs predominantly in hepatic Kupffer cells and splenic macrophages. In contrast, removal of blood-borne particulates in calves, sheep, goats, cats, and pigs occurs predominantly in pulmonary intravascular macrophages (PIMs). Review of recent studies indicates that PIMs are a resident cell population, junctionally adherent to the capillary endothelium of lungs and morphologically similar to hepatic Kupffer cells. PIMs are a pulmonary constituent of the mononuclear phagocyte system with respect to secretory, endocytic, and functional properties. Differentiated PIMs are rare in newborn pigs, and the majority of cells closely apposed to capillary endothelium consists of monocytes, which are occasionally in mitosis. In 7-day-old and older pigs, most cells apposed to capillary endothelium have characteristics of differentiated PIMs. This suggests a monocytic origin of PIMs in pigs. Perinatal colonization of lung capillaries by monocytes and their subsequent differentiation into PIMs represent a component of postnatal lung development. Estimates of relative PIM numbers in ovine and porcine lung parenchyma suggest cell densities similar to that of rat hepatic Kupffer cells. Apart from phagocytic properties, PIMs participate in the removal and disintegration of aged and impaired blood cells. After phagocytic stimulation, isolated PIMs secrete oxygen radicals, which are essential for microbicidal function. Similarly, by secreting bioactive lipids, stimulated PIMs may contribute to regulation of pulmonary hemodynamics. After receiving minute amounts of bacterial endotoxin, pulmonary injury is pronounced in sheep, calves, pigs, and cats, but not in laboratory animals and dogs. This presumably is related to the secretion of bioactive lipids by PIMs.

In Vitro and in Vivo Studies of Poly-L-Lysine as Inducer of Friend Leukemic Cells Differentiation

Poly-L-lysine, a synthetic cationic polypeptide known for its ability to bind to cell membranes, was found to induce differentiation of Friend leukemia cells « in vitro ». Studies were extended to the same « in vivo » model, in order to examine the therapeutic potential of this new differentiating agent. The i.p. administration of the polymer (Mw 2700) at the maximal tolerated dose resulted in major alterations of disease-related parameters. In particular, a multiple treatment schedule on the advanced disease resulted in a successful reduction of target organ weight and peripheral white blood cell count and appreciable differentiation of spleen and bone marrow cells. Apparently, the effects of poly-L-lysine were superior to those produced by N-methyl-acetamide, a potent inducer of differentiation « in vitro ».

Immunophenotyping of acute non-lymphoblastic leukaemias

Using monoclonal antibodies specific for myelomonocytic cells, 40 non-lymphoblastic leukaemias were analysed applying immunostaining to cytospin preparations. Based on the reactivity patterns six groups of acute non-lymphoblastic leukaemias could be determined, mirroring the bimodal differentiation pathway of myelomonocytic cells. Comparative enzyme cytochemical analysis did not render a clear cut correlation and discrimination of the immunocytochemically defined groups. It is concluded that only the application of a broad panel of immunocytochemical and enzyme cytochemical methods allow a sound subdivision and diagnosis of acute non-lymphoblastic leukaemias.

Alternative myelomonocytic differentiation of HL-60 reflects dual prospective potency of promyelocytes in human

The permanent promyelocytic cell line HL-60 was subjected to stimulation with dimethyl sulfoxide (DMSO) and retinoic acid (RA), as well as 12-O-tetradecanoylphorbol-13-acetate (TPA) and lymphokine conditioned media for the induction of granulocytic or monocytic differentiation, respectively. Cells were investigated cytochemically using alpha-naphthylacetate esterase (acid esterase; AcE), naphthol AS-D chloroacetate esterase, and peroxidase reactions. In addition, the granulocyte or monocyte specific isoenzyme patterns of AcE as an intracytoplasmic property and the immunoreactivity to monoclonal antibodies recognizing granulocytes and monocytes (Ki-M2, Ki-M5) or monocytes alone (Ki-M1) were considered. The results indicated that HL-60 cell line bear the potency to evolve into granulocytes as well as monocytes. Additional studies performed on normal human bone marrow stained for AcE led to the conclusion that the myeloid cell line remains bipolar until the maturation stage of promyelocytes. Myelocytes being AcE positive only in 11.5 +/- 5.0 are heterogeneous and display the first indications of separated monocytic or granulocytic differentiation.

Immune interferon and leukocyte-conditioned medium induce normal and leukemic myeloid cells to differentiate along the monocytic pathway

Conditioned medium from phytohemagglutinin-stimulated human leukocytes contains a factor that can induce promyelocytic cell lines and certain acute myelogenous leukemia cells to differentiate along the monocytic pathway. In this report, we show that immature myeloid cells from normal bone marrow or the peripheral blood of patients with chronic myelogenous leukemia can be induced to differentiate to monocyte-like cells by immune gamma interferon (IFN gamma). We have identified IFN gamma as the predominant differentiation factor contained in the conditioned medium. Purified or recombinant IFN gamma, but not various preparations of IFN alpha or beta, can induce monocytic differentiation in myeloid cells. In cultures containing conditioned medium, the cells fail to continue myeloid maturation, and are induced to express monocyte markers and functions, such as monocyte-specific surface antigens, HLA-DR antigens, Fc receptors for monomeric immunoglobulins, nonspecific esterase, and the ability to mediate antibody-dependent, cell-mediated cytotoxicity. Even myeloid cells as mature as metamyelocytes or band cells can be induced by IFN gamma to undergo monocyte differentiation, but monocyte-specific or HLA-DR antigens are not induced in mature neutrophils. These findings reveal a previously unknown, specific function of human IFN gamma and offer new insights to the regulation of monocyte recruitment and differentiation during a virus infection or immune response.

Polymorphism of acid hydrolases in human epitheliod cells indicates cellular origin and defined differentiation stages

The following work was planed to clarify whether enzyme variants were appropriate in disclosing cellular derivation and in indicating defined differentiation stages of stimulated cells. Light and electronmicroscopical studies have revealed a close relationship between monocytes, tissue macrophages, and epithelioid cells. In the present investigation direct evidence was provided for the monocytic origin of epithelioid cells. It could be shown that the monocyte specific isoelectric focusing patterns of acid phosphatase (EC 3.1.3.2) and nonspecific acid esterase (EC 3.1.1.6) were regularly shared by epithelioid cells, obtained from lymph nodes of patients with sarcoidosis. Concerning additional isoenzymes of epithelioid cells in comparison to blood monocytes and peritoneal macrophages, it is concluded that the analysis of enzyme polymorphism might be a reliable tool for tracing cell lineage and for defining functional stages during cell differentiation.

Acute monocytic leukemias

Normal monocytes and macrophages are characterized by peculiar ultrastructural and cytochemical features and, in addition, show characteristic membrane properties, a variety of special functional capacities, and important secretory activities. Almost all these cytological features can also be detected in leukemic monocytic cells, and it is quite conceivable that these peculiar features may influence or determine the clinical syndrome associated with the leukemic accumulation of monocytic cells. The morphological identification of monocytic leukemias is a very intriguing diagnostic problem and some controversies still exist concerning their cytological classification. For clinical as well as scientific purposes the diagnosis of monocytic leukemias should rely on the demonstration of specific monocytic features of the leukemic cells. Clinical findings frequently associated with acute monocytic leukemia include increased frequency of leukemic tissue infiltrations as well as increased tendency to hypokalemia and - especially in the "immature" variants - to disorders of hemostasis.

Phagocytosis in acute leukemia

The phagocytic potential of leukemic cells in various types of acute leukemia was studied. Cases included lymphoblastic leukemia, myeloblastic leukemia, myelomonocytic leukemia, monocytic leukemia, progranulocytic leukemia, blast transformation of chronic myelocytic leukemia, and unclassified leukemias. Cytochemical stains were used as an aid in classification. These included Sudan black B, naphthol AS-D chloroacetate esterase, alpha-naphthyl butyrate esterase, acid phosphatase, and periodic acid-Schiff. Phagocytosis was evaluated after incubation of leukemic cells with Candida albicans. Rare phogocytic activity was seen in lymphoblastic leukemia, unclassified leukemias, blast crises in chronic myelocytic leukemia, and progranulocytic leukemia. Myeloblastic leukemias were feebly phagocytic. Myelomonocytic leukemia and monocytic leukemia both exhibited marked phagocytosis which distinguished them from the other acute leukemias. Myelomonocytic leukemia could be differentiated from acute monocytic leukemia by its greater phagocytic capacity.

Acid phosphatase in leukemic blasts: characterization by isoelectric focusing in polyacrylamide gel

Using the high resolution technique of isoelectric focusing in polyacrylamide gel, isoenzymatic components of acid phosphatase were detected in cell-free extracts prepared from different cytologic types of leukemic blasts in adults. Results indicate that for different cytologic types, different characteristic patterns of acid phosphatase isoenzyme could be detected. These studies extend conventional cytochemistry and indicate that characteristic patterns of acid phosphatase isoenzyme can be detected for various cytologic types of acute leukemia.

On the terms "reticulosis" and "reticulum cell sarcoma" with regard to the modern concept of the monocyte macrophage system

The terms "reticulosis" and "reticulum cell sarcoma" (=malignant lymphoma, histiocytic type) are discussed regarding the modern concept of the monocyte macrophage system which today has replaced the ancient theory of the reticuloendothelial system. The monocyte macrophage system which today has replaced the ancient theory of the reticuloendothelial system. The monocyte macrophage system is not independent, but closely related to the myeloid system. Thus, a third blood forming system as was believed in the case of RES does not exist. Phagocytic reticulum cells of the various henatopoietic organs are highly activated monocyte-derived macrophages. All those conditions formerly termed "reticulosses" have been found to belong either to the myeloid or to the lymphatic system. Considering the reticulum cell sarcomas or malignant histiocytic lymphomas, most of them seem to be of lymphatic rather than of macrophage origin, representing highgrade malignant lymphomas, possibly immunoblastic sarcomas. No relationship between these tumours and the monocyte macrophage system has been established, so far. Therefore, the terms "reticulosis" and "reticulum cell sarcoma" should be no longer used in order to avoid confusion, in order to stimulate sufficient diagnostic efforts which will really clarify such cases, and in order to give full credit to modern results of hematopathology.

Cell surface antigens detected on mature and leukemic granulocytic populations by cytotoxicity testing

Using a microcytotoxicity assay, the serological reactivity of human granulocytes, namely neutrophils and eosinophils, and chronic myeloid leukemia (CML) cells and cultured CML cell lines (K562, NALM-1) were examined. Mature granulocyte forms and cord granulocytes are readily lysed by specific granulocyte cytotoxins that do not react with random T and B lymphocytes, monocytes, red blood cells, or platelets. Furthermore, certain antisera were preferentially cytotoxic for eosinophil-enriched populations. Granulocytotoxin detected antigens on one of three CML blast cell populations tested and K562, but failed to react with NALM-1. By cytotoxicity, mature granulocytes were poor targets for B2-microglobulin and the appropriate HLA antisera although both sera types are absorbed with granulocytes. Furthermore, granulocytes did not possess B-lymphocytes (Ia-like) or blood group A, B, and Rh (D) antigens. Except for K562, both HLA and heterologous B-lymphocyte antisera were cytotoxic for the CML blast cell populations tested.

Serological characterization of human monocytes for HLA, B-lymphocyte, granulocyte, and monocyte-associated antigens by cytotoxicity testing

Highly enriched preparations of monocytes, B and T lymphocytes, and granulocytes from 18 normal donors were serotyped in parallel in a complement-dependent cytotoxicity assay using allogeneic and heterologous antisera defining three independent tissue antigen systems. HLA and B-lymphocyte tissue antigens were detected on human monocytes although granulocyte antigens were absent. By cytotoxicity testing the presence of Ia-like antigens on monocytes was significantly diminished compared to the autologous B-lymphocyte population and has important implications in B-lymphocyte serology. The study indentified a number of human antisera obtained from multitransfused subjects and pre- and post-transplant organ recipients that were non-HLA and appeared to define monocyte-associated antigens. The serological implications of surface antigen expression on human monocytes compared with other peripheral blood cells are discussed.

Classification of lymphomas

Malignant lymphomas are neoplasms of cells of the lymphoreticular or immune system. Classification of these neoplasms has long been controversial and confusing. In recent years, considerable progress has been made in establishing useful and prognostically significant classifications of lymphomas. Currently, lymphomas may be divided into two main groups: Hodgkin's disease and non-Hodgkin's lymphomas. The Rye classification of Hodgkin's disease is now widely accepted and used throughout most of the world. In contrast, considerable conflict exists about the schemes of non-Hodgkin's lymphomas. The traditional classifications of non-Hodgkin's lymphomas currently used by most pathologists are based purely on morphologic grounds, and, despite the fact that they may be conceptually incorrect, they have often been shown to be useful for clinicopathologic studies. New or modern but yet untested schemes based not only on morphologic criteria, but also on recent immunologic techniques, have been proposed. This work will review the classifications of Hodgkin's disease and the non-Hodgkin's lymphomas, emphasizing the currently used schemes, describe the major modern classifications of lymphomas, and discuss and illustrate the subclasses of lymphomas and the differential diagnoses of the various types of lymphomas from nonlymphomatous proliferations which may mimic them.

[Frequency and valuation of epitheloid cell granulomas of the spleen in morbus Hodgkin (author's transl)]

Macroscopic and microscopic examination of 154 spleens from patients with lymphogranulomatosis revealed focal alterations in 71 (46%) specimens, 55 ( equals 36%) of which showed typical Hodgkin granuloma while in 16 cases ( equals 10%) the granulomas present were composed of epitheloid cells only. In casu, both Hodkin and epitheloid cell granulomas were macroscopically visible and occurred in normal-sized as well as in enlarged (is greater than 250 g) spleens. However, unspecific alterations had led to splenomegaly, too. The presence of epitheloid cell granulomas in spleens in M. Hodgkin proves that the granulomas indeed are causal pathogenetically linked with lymphogranulomatosis, but are to separate from it substantially. Epitheloid cell granulomas are interpreted as a reaction of the mononuclear phagocyte system in lymogranulomatosis and not as a manifestation of lymphogranulomatosis itself. This should be considered in clinical staging.

Identification and characterization of the monoblast in mononuclear phagocyte colonies grown in vitro

A liquid culture technique for growing mononuclear phagocyte colonies on a glass surface is described. This useful and reliable technique made it possible to study immature mononuclear phagocytes. In the mononuclear phagocyte colonies the cells grow separate from each other in a single layer. Three types of cells are recognized in these colonies, namely nondividing macrophages, and proliferating promonocytes and monoblasts. The macrophage and the promonocyte exhibit the typical characteristics previously demonstrated by the other methods, whereas the monoblast could only be fully characterized by the present liquid culture method. This proliferating cell (labeling index with [3H]thymidine, 92-96%) is almost round (diameters, 10 X 10 mum), has only a small rim of strongly basophilic cytoplasm, almost devoid of granules, and shows a certain degree of ruffling of the cell surface. The monoblast is positive for esterase with alpha-naphthyl butyrate as substrate (91%), for peroxidase (78% in the peroxidase-positive colonies), and lysozyme (43%). The monoblast is able to pinocytize dextran sulphate (15-20%) and to phagocytize opsonized bacteria (20-30%), latex particles (47%), and IgG-coated red cells (96%). IgG receptors (94%) and complement receptors (16%) are present at the cell surface. In these respects the monoblast has the typical characteristics of the mononuclear phagocytes, but its properties show it to be a more immature cell type than the promonocyte. On the basis of these criteria and the sequence of appearance of the different cell types during incubation and during the development of the individual mononuclear phagocyte colony, monoblasts being present before promonocytes appear in the colony, it is concluded that the monoblast is the precursor of the promonocyte. In these cultures granulocyte colonies are also formed, consisting of myeloblasts, (pro)myelocytes, stabs, and polymorphonuclear neutrophils. Besides the typically tight structure of this kind of colony, the granulocytic cells themselves are quite distinct from the mononuclear phagocytes by their morphology, cytochemical characteristics (e.g. all negative for esterase with alpha-naphthyl butyrate, but 96% positive with N-acetyl DL-alanyl 1-naphthylester), functional characteristics (pinocytic index 13-21%; phagocytic index; for opsonized bacteria 15-36%, for latex particles 10%, and for IgG-coated red cells 0%), and their very small number of IgG receptors and lack of complement receptors. On the basis of these criteria, these granulocytic cells are easily distinguished from the immature cells of the mononuclear phagocyte colonies. The present study confirms the conclusion that the mononuclear phagocytes are a separate cell line, quite distinct from the granulocytic series, since even the most immature cells so far identified--the monoblast and the myeloblast--have quite different characteristics.

Nodular lymphoma: bone marrow and blood manifestations

Morphological and clinical features of 39 patients with nodular lymphoma were studied with particular reference to bone marrow and blood involvement. Twenty-one patients (54%) were found to have bone marrow involvement at the time of initial diagnosis. Thirteen (33%) also had peripheral blood involvement. A specific cell type, the small nodular lymphoma cell, was found in the bone marrow smears of 19 and the 21 patients with bone marrow involvement and in the peripheral blood smears of all patients with blood involvement. When large cells predominated in the lymph node or bone marrow sections, the bone marrow smears and the imprints of the lymph node and trephine biopsy demonstrated these large cells to have morphological qualities of lymphocytes rather than histiocytes.

"Pure" monocytic or histiomonocytic leukemia: a revised concept

In a series of 130 cases of acute leukemia studied by cytochemical staining techniques, 10 cases cytochemically diagnosed as "pure" monocytic leukemia were seen. Cytochemical staining of bone marrow aspirates from these patients revealed all leukemic cells to be Sudan black negative. No positive reactions were observed for peroxidase or naphthol AS-D chloroacetate esterase. All cases demonstrated strong alpha-naphthyl acetate esterase positivity; and fluoride-inhibited naphthol AS-D acetate esterase positivity was observed in 8 of 9 cases tested. The P.A.S. reaction showed diffuse fine to coarse granules. Oil red O stain was positive in 8 of 9 cases, and the beta-glucuronidase activity was strong in 5 of 9 cases. Light microscopy revealed cells with monocytic or histiocytic morphology. Electron microscopic studies in 2 cases demonstrated features consistent with leukemic monocytic or histiocytic morphology; none was suggestive of granulocytic or lymphocytic leukemia. Five of 6 patients treated with drug regimens including prednisone and vincristine entered a complete remission; the other obtained a partial remission. Two patients achieved complete remission after treatment with Adriamycin, 1 following a relapse. Three patients who received cytosine arabinoside as their only therapy died soon after treatment was commenced. It is suggested that the cytochemical similarity but morphological differences in those patients may be objectively used to group them as cases of histiomonocytic leukemia.

Human blood monocytes: stimulators of granulocyte and mononuclear colony formation in vitro

Human blood monocytes in a feeder layer or by use for conditioning medium produced a colony-stimulating factor capable of stimulating the in vitro growth of colonies of granulocytes and mononuclear cells from human and murine marrow. Lymphocytes and neutrophils did not stimulate colony formation, and medium conditioned by neutrophils was inhibitory. This suggests that the monocyte may control granulocyte proliferation and maturation.