The cytokinetics of monocytosis in acute salmonella infection in the rat

Proliferation of monocytes and macrophages in homeostasis, infection, injury, and disease

Monocytes (Mo) and macrophages (Mφ) play important roles in the function of tissues, organs, and systems of all animals during homeostasis, infection, injury, and disease. For decades, conventional wisdom has dictated that Mo and Mφ are end-stage cells that do not proliferate and that Mφ accumulation in tissues is the result of infiltration of Mo from the blood and subsequent differentiation to Mφ. However, reports from the early 1900s to the present describe evidence of Mo and Mφ proliferation in different tissues and contexts. The purpose of this review is to summarize both historical and current evidence for the contribution of Mφ proliferation to their accumulation in different tissues during homeostasis, infection, injury, and disease. Mφ proliferate in different organs and tissues, including skin, peritoneum, lung, heart, aorta, kidney, liver, pancreas, brain, spinal cord, eye, adipose tissue, and uterus, and in different species including mouse, rat, rabbit, and human. Mφ can proliferate at different stages of differentiation with infiltrating Mo-like cells proliferating in certain inflammatory contexts (e.g. skin wounding, kidney injury, bladder and liver infection) and mature resident Mφ proliferating in other inflammatory contexts (e.g. nematode infection, acetaminophen liver injury) and during homeostasis. The pathways involved in stimulating Mφ proliferation also may be context dependent, with different cytokines and transcription factors implicated in different studies. Although Mφ are known to proliferate in health, injury, and disease, much remains to be learned about the regulation of Mφ proliferation in different contexts and its impact on the homeostasis, injury, and repair of different organs and tissues.

Quambalarine B, a Secondary Metabolite from Quambalaria cyanescens with Potential Anticancer Properties

Quambalarine B (QB) is a secondary metabolite produced by the basidiomycete Quambalaria cyanescens with potential anticancer activity. Here we report that QB at low micromolar concentration inhibits proliferation of several model leukemic cell lines (Jurkat, NALM6, and REH), whereas higher concentrations induce cell death. By contrast, the effect of QB on primary leukocytes (peripheral blood mononuclear cells) is significantly milder with lower toxicity and cytostatic activity. Moreover, QB inhibited expression of the C-MYC oncoprotein and mRNA expression of its target genes, LDHA, PKM2, and GLS. Finally, QB blocked the phosphorylation of P70S6K, a downstream effector kinase in mTOR signaling that regulates translation of C-MYC. This observation could explain the molecular mechanism behind the antiproliferative and cytotoxic effects of QB on leukemic cells. Altogether, our results establish QB as a promising molecule in anticancer treatment.

Increased monocyte turnover from bone marrow correlates with severity of SIV encephalitis and CD163 levels in plasma

Cells of the myeloid lineage are significant targets for human immunodeficiency virus (HIV) in humans and simian immunodeficiency virus (SIV) in monkeys. Monocytes play critical roles in innate and adaptive immunity during inflammation. We hypothesize that specific subsets of monocytes expand with AIDS and drive central nervous system (CNS) disease. Additionally, there may be expansion of cells from the bone marrow through blood with subsequent macrophage accumulation in tissues driving pathogenesis. To identify monocytes that recently emigrated from bone marrow, we used 5-bromo-2′-deoxyuridine (BrdU) labeling in a longitudinal study of SIV-infected CD8+ T lymphocyte depleted macaques. Monocyte expansion and kinetics in blood was assessed and newly migrated monocyte/macrophages were identified within the CNS. Five animals developed rapid AIDS with differing severity of SIVE. The percentages of BrdU+ monocytes in these animals increased dramatically, early after infection, peaking at necropsy where the percentage of BrdU+ monocytes correlated with the severity of SIVE. Early analysis revealed changes in the percentages of BrdU+ monocytes between slow and rapid progressors as early as 8 days and consistently by 27 days post infection. Soluble CD163 (sCD163) in plasma correlated with the percentage of BrdU+ monocytes in blood, demonstrating a relationship between monocyte activation and expansion with disease. BrdU+ monocytes/macrophages were found within perivascular spaces and SIVE lesions. The majority (80–90%) of the BrdU+ cells were Mac387+ that were not productively infected. There was a minor population of CD68+BrdU+ cells (<10%), very few of which were infected (<1% of total BrdU+ cells). Our results suggest that an increased rate of monocyte recruitment from bone marrow into the blood correlates with rapid progression to AIDS, and the magnitude of BrdU+ monocytes correlates with the severity of SIVE.

Human immunodeficiency virus (HIV) and the closely related simian immunodeficiency virus (SIV) can infect monocyte/macrophages, which enter and accumulate in the brain leading to neuronal dysfunction. Monocyte/macrophages exit the bone marrow, transit through the blood and enter the central nervous system (CNS). What triggers these cells to traffic is undefined, but it occurs in normal non-infected conditions at a rate that is accelerated with viral infection. Here, we used 5-bromo-2′-deoxyuridine (BrdU) injection and incorporation into the DNA of monocytes prior to their departure from the bone marrow. We found that the percentage of BrdU+ monocytes leaving the bone marrow 24 hours after injection increased in animals that rapidly succumbed to AIDS and correlated with the severity of SIV encephalitis (SIVE). Differences in BrdU labeled monocytes in slow and rapid progressors were revealed as early as 8 days and were consistent by 27 days post infection. Soluble CD163, shed by activated monocyte/macrophages, directly correlated with BrdU+ monocyte expansion. Our study provides new insights into the development of HIV-related CNS disease and underscores the importance of monocyte/macrophage recruitment from the bone marrow as an AIDS defining event.

The level of monocyte turnover predicts disease progression in the macaque model of AIDS

It is widely accepted that destruction of CD4(+) T cells and viral load are the primary markers for immunodeficiency in HIV-1-infected humans and in simian immunodeficiency virus (SIV)-infected macaques. However, monocyte/macrophages are also important targets of HIV/SIV infection and a critical link between innate and adaptive immunity. We therefore examined whether changes in cells of the monocyte/macrophage lineage could be linked to the pathogenesis of AIDS in the rhesus macaque model. Here, we show that massive turnover of peripheral monocytes associated with death of tissue macrophages correlates with AIDS progression in macaques. More importantly, the level of monocyte turnover was not linked to the CD4(+) T-cell count and was a better predictive marker for AIDS progression than was viral load or lymphocyte activation. Our results show the importance of monocyte/macrophages in the pathogenesis of AIDS and suggest the dynamic changes of the monocyte/macrophages as a new marker for AIDS progression.

Altered monocyte and macrophage numbers in blood and organs of chickens injected i.v. with lipopolysaccharide

Lipopolysaccharide (LPS) is a Gram-negative bacteria cell wall component that activates monocytes and macrophages to produce nitric oxide (NO) from inducible nitric oxide synthase. Nitric oxide production in the plasma of chickens peaks 5-6-h post-i.v. LPS injection reflecting iNOS activation. To determine monocyte responsiveness after an i.v. LPS injection, a time course study was conducted examining the concentrations among peripheral blood leukocytes post-i.v. LPS injection in male and female chickens, the proportions among peripheral mononuclear leukocyte (PBMC; containing lymphocytes, thrombocytes, and monocytes) populations isolated from the blood samples collected at various times post-i.v. LPS treatment, and the ability of monocytes to produce NO with and without further LPS stimulation in vitro using the PBMC NO production assay. Additionally, monocyte extravasation activity was determined by analyzing macrophage proportions after the i.v. LPS injection in spleen, lung, and liver tissues. Blood was collected from male and female chickens at 0 h (pre-LPS injection control) and at 1, 3, 6, 24, and 48 h post-LPS injection, and additionally, at 72 h from female chickens. Tissues were collected 0, 1, 6, and 48 h post-i.v. LPS injection from male chickens. Monocyte concentrations dropped substantially by 1h in both males and females. In males, monocyte concentrations returned to control concentrations by 6h and increased at 24- and 48-h post-LPS injection, whereas in females, monocyte concentrations recovered more slowly, returning to near control concentrations by 24-48-h and increasing above control levels by 72 h. Lipopolysaccharide stimulated NO production by PBMC cultures established from blood samples obtained at various times post-LPS injection in vivo followed the same pattern as monocyte concentrations in the blood. Hence, NO concentrations within PBMC cultures were dependent upon the number of monocytes that were in the PBMC cultures isolated at different times post-i.v. LPS injection. Furthermore, macrophage proportions in spleen tissues responded similarly to monocyte concentrations in the blood, decreased in lung tissue, and varied widely in liver tissue throughout 48 h after an LPS injection. Monocytes and other leukocytes may attach to the endothelium post-i.v. LPS injection preventing the monocytes from entering the needle during blood collection resulting in what seems to be leukopenia in blood and in PBMC cultures attenuating NO production in PBMC cultures. Furthermore, monocyte differentiation and recruitment from the bone marrow is a likely contributor to the reconstitution and rise of monocyte concentrations in blood samples post-i.v. LPS injection.

A novel method to quantify the turnover and release of monocytes from the bone marrow using the thymidine analog 5'-bromo-2'-deoxyuridine

The present study was designed to develop methods to study the production and release of monocytes from the bone marrow using the thymidine analog 5'-bromo-2'-deoxyuridine (BrdU). Dividing monocytes in bone marrow were labeled with BrdU (MOBrdU), and their release into the blood and disappearance from the circulation were monitored using a double immunostaining method. The first MOBrdU appeared in the circulation 4 h after labeling with BrdU and peaked at 18 h when 34.3 +/- 5.8% of monocytes were labeled. The calculated transit time of monocytes through bone marrow was 38.1 +/- 3.1 h in control rabbits with a half-life (T1/2) of 12.7 h. Instillation of Streptococcus pneumoniae into the lung accelerated the release of monocytes from bone marrow (peak at 10 h) and shortened their bone marrow transit time (27.1 +/- 1.8 vs. 22.6 +/- 0.6, vehicle vs. pneumonia; P < 0.05). We conclude that this nonradioisotope method provides a novel way to monitor monocyte kinetics and confirmed previous reports that a focal pneumonia shortens monocyte marrow transit and increases their release into the circulation.

A rat model for dose-response relationships of Salmonella Enteritidis infection

AIMS

To develop an animal model to study dose-response relationships of enteropathogenic bacteria.

METHODS AND RESULTS

Adult, male Wistar Unilever rats were exposed orally to different doses of Salmonella enterica serovar Enteritidis after overnight starvation and neutralization of gastric acid by sodium bicarbonate. The spleen was the most sensitive and reproducible organ for detection of dose-dependent systemic infection. Illness was only observed in animals exposed to doses of 10(8) cfu or more. At lower doses, histopathological changes in the gastro-intestinal tract were observed, but these were not accompanied by illness. Marked changes in numbers and types of white blood cells, as well as delayed-type hyperresponsiveness, indicated a strong, dose-dependent cellular immune response to Salm. Enteritidis.

CONCLUSION

The rat model is a sensitive and reproducible tool for studying the effects of oral exposure to Salm. Enteritidis over a wide dose range.

SIGNIFICANCE AND IMPACT OF THE STUDY

The rat model allows controlled quantification of different factors related to the host, pathogen and food matrix on initial stages of infection by food-borne bacterial pathogens.

Antimicrobial functions of mononuclear phagocytes

One of the major functions of mononuclear phagocytes, i.e., monocytes and macrophages, is the phagocytosis and killing of microorganisms. To obtain more insight into the pathogenesis of infectious diseases and to develop new therapies against these diseases, a better understanding of the antimicrobial mechanisms employed by mononuclear phagocytes is essential. The present review gives a short description of the mononuclear phagocyte system and summarizes various methods that are used to study the antimicrobial mechanisms of mononuclear phagocytes.

Production of tumor necrosis factor, interleukin-6 and prostaglandin E2 by LPS-stimulated rat bone marrow macrophages after thermal injury: effect of indomethacin

The effect of thermal injury on the in vitro production of TNF, IL-6, and PGE2 by bone marrow-derived, LPS-stimulated rat macrophages was studied. Thermal injury caused a general hyperactivity in the production of the mediators by the cells. Indomethacin, a cyclooxygenase inhibitor of PGE2 synthesis, inhibited the production of IL-6 and PGE2 but had no effect on the production of TNF. These results suggest that the observed low concentration of PGE2 produced by the cells was insufficient to cause inhibition of TNF synthesis; thus, the effect of indomethacin would be undetectable. The results also suggest that indomethacin may act directly in inhibiting the production of IL-6 by the macrophages. The hyperactive effect of thermal injury on the production of inflammatory mediators by newly differentiated bone marrow derived macrophages can be important in the overall systemic response to the insult.

Gamma interferon treatment in vivo provokes accumulation of activated monocytes in the venous circulation of rats

Activated monocytes forming intravascular clumps in the veins of most organs appeared in LEW rats after a 3-day intravenous treatment with recombinant rat gamma interferon. Phenotyping in situ and in cytospot preparations of perfusates revealed that the cells coexpressed the rat monocyte/macrophage antigen ED1 and class II MHC molecules. In addition, most cells reacted with a rat CD11b antibody and weakly expressed determinants detected by the W3/13 and Ox22 reagents. Minor fractions of the activated monocytes were positive for rat CD4 and the Ox2 and ED3 determinants. Cell proliferation was assessed by double staining for bromodeoxyuridine (BrdUrd) incorporation and phenotypic markers. Of the ED 1-positive class II-positive cells, 80% were labeled with BrdUrd after 3 days of combined infusion with gamma interferon. Pulse labeling for 30 minutes revealed 8% BrdUrd-positive intravascular ED 1-positive class II-positive monocytes in situ on day 3 of treatment, which contrasted with almost-absent labeling of this cell population in normal LEW rats. It is concluded that interferon not only promotes activation but also intravascular division of monocytes or their immediate precursors. Interestingly, cells of identical morphology and phenotype were observed in the vasculature of rats during lethal graft-versus-host reactions. Activated monocytes may thus contribute to the pathologic consequences of cytokine treatment and severe systemic immune reactions in vivo.

[Cellular components in interstitial lung tissue in sudden infant death--immunohistochemical characterization]

Monoclonal antibodies against the Leucocyte Common Antigens LC and MAC-387 expressed by lymphocytes, mononuclear phagocytes and polymorphonuclears failed to mark the cells of the pulmonary interstitial connective tissue in cases of SIDS. Controls with interstitial pneumonia showed clearly marked inflammatory cells. Although focal proliferation of cells was frequently observed in the vicinity of distended lymphatics in SIDS cases, an inflammatory origin as in the cases of interstitial pneumonia could not be confirmed. A relationship between interstitial edema and a non-inflammatory proliferation of the cells is discussed.

Assay for quantitation of mature monocytes in murine haemopoietic tissues

We propose a new assay which allows the extent of production of mature monocytes in murine haemopoietic tissues to be monitored with precision. To develop such a quantitative assay, we chose a T-cell function easily detectable in vivo, namely the ability of T lymphocytes to locally transfer a delayed-type hypersensitivity (DTH) reaction. T cells co-transferred with antigen into footpads of syngeneic mice are mediators of DTH through their ability to recruit phagocytes recently produced in haemopoietic tissues. Therefore, if recipients of DTH-mediating T cells (DTH-T cells) are depleted of phagocytes by lethal irradiation given 36 to 48 h before local transfer of these DTH-T cells mixed with antigen, they no longer respond by a DTH reaction, measured as an increase in footpad thickness, unless they receive i.v. bone marrow cells as a source of recruitable phagocytes. In such conditions, the footpad thickness increase is linearly related to the number of cells injected i.v. Pretreatment of bone marrow cells with the rat IgG2b F4/80 monoclonal antibody abolishes their ability to restore expression of DTH, indicating that monocytes (F4/80+ cells) are the phagocytes to be measured. This assay system thus provides a means of measuring levels of recruitable mature monocytes present in haemopoietic tissues. One illustration of the assay is given by the study of the recovery of recruitable phagocytes in bone marrow following a single treatment with cyclophosphamide.

Sequential morphological and quantitative changes in blood and bone marrow neutrophils in dogs with acute inflammation

Blood and bone marrow morphology were studied sequentially in dogs during experimental inflammation induced by intramuscular injection of turpentine. Depletion of the bone marrow storage pool of mature neutrophils and an increase in mitotic activity and number of early granulocyte precursors were evident within 24 hours. During the next three days, intense granulocytic hyperplasia resulted in replenishment of the bone marrow storage pool. Neutrophils with foamy vacuolation and increased basophilia of the cytoplasm (toxic neutrophils) were present in the blood by eight hours postinjection. The number of toxic neutrophils paralleled the intensity of clinical signs and changes in rectal temperature but not the number of band neutrophils. This indicates that changes in number of toxic neutrophils in sequential leukograms can be a prognostic indicator in dogs with severe inflammation.

Characterization of nonlymphoid cells derived from rat peripheral lymph

Mesenteric lymphadenectomy in rats is followed by union of peripheral and central lymphatics, allowing the collection of intestine-derived peripheral lymph cells via the thoracic duct for several days. These cells include a proportion of nonlymphoid cells (NLC) that show irregular and heterogeneous surface morphology including long pseudopodia and veils. They stain variably for nonspecific esterase and acid phosphatase and are ATPase-positive. Their nuclei are irregular and some contain cytoplasmic inclusions, some of which show peroxidase activity and/or contain DNA. NLC have a range of densitites generally lower than that of lymphocytes. Freshly collected NLC express the leukocyte-common antigen (defined by monoclonal antibody MRC Ox 1) and Ia antigens (I-A and I-E subregion products defined by monoclonal antibodies) but they show a relative lack of other surface markers normally found on rat B or T lymphocytes (W3/13, W3/25, MRC Ox 12 (sIg), MRC Ox 19) or rat macrophages (FcR, C'R, mannose R, W3/25). In general NLC are only weakly adherent to glass or plastic. Although a subpopulation of NLC appear to have had a phagocytic past, freshly collected NLC fail to phagocytose a variety of test particles in vitro. NLC also appear incapable of pinocytosis in vitro. This heterogeneity may represent distinct subpopulations of NLC or different stages in the development of a single cell lineage. Direct cannulation of mesenteric lacteals shows that the majority of NLC are derived from the small intestine and their precursors appear to be present both in lamina propria and Peyer's patches. Kinetic studies, following irradiation or intravenous tritiated thymidine, show that the majority of NLC turn over rapidly in the intestine with a modal time of 3-5 d. Studies with bone marrow chimeras show that they are derived from a rapidly dividing precursor present in normal bone marrow. NLC occur at very low frequencies in normal thoracic duct lymph at all times following cannulation. The evidence presented suggests that NLC closely resemble mouse lymphoid dendritic cells. This conclusion is supported by evidence already obtained showing that NLC are potent stimulators of the semi-allogeneic rat primary mixed leukocyte reaction. In addition to the ceils resembling dendritic cells rare monocytoid cells are found in thoracic duct lymph of lymphadenectomized specific pathogen-free rats. The proportion of these cells increases greatly when the animals are conventionally housed. It seems probable that the physiological function of NLC is to act as accessory cells in the lymph nodes to which they normally drain. Methods for enriching NLC and thus facilitating analysis of their functions are discussed.

Cellular basis for genetically determined enhanced resistance of certain mouse strains to listeriosis

The characteristics of the mononuclear phagocytes mediating resistance to infection with Listeria during the early phase (0 to 48 h) of the response have been investigated in genetically determined susceptible (A/J) and resistant (C57BL/6, B10.A/SgSn) strains of mice. Irradiation immediately before infection profoundly enhanced the bacterial growth in the resistant strain, while having no effect in the susceptible strain, over a wide range (3 x 10(3) to 10(5)) of infective doses. This effect of irradiation is demonstrable at low-dose radiation (200 roentgens) and can be reversed by repopulation with 20 x 10(6) syngeneic nucleated bone marrow cells. Administration of dextran sulfate 500 24 h before infection profoundly enhanced the bacterial growth in the susceptible strain, while having much less effect in the resistant strain. Thus, the genetic advantage of the resistant mouse strains to listerial infection, at least during the early phase of the response, appears to be due to a cellular mechanism that is highly radiosensitive and relatively insensitive to dextran sulfate 500. In the susceptible strain, the early protective cellular mechanism is radioresistant and highly dextran sulfate 500 sensitive.

Accumulation of eosinophils and monocytes in lymphoid organs of chick-embryos. I. Effect of antigenic stimulation

The effect of antigenic stimulation on the migration pattern of eosinophils and monocytes was studied during the embryonic stage in chickens. On the 13th embryonic day, chickens were injected with sheep red blood cells as antigen into the allantoic cavity and the relative frequency of oxidase positive cells (OPC) was determined as the total number of eosinophils and monocytes in the bursa of Fabricius, spleen, and thymus. Three and five days after the antigenic stimulation, the frequencies of OPC increased in both the spleen and thymus and then decreased to the normal level just before hatching. However, bursal frequencies of OPC were always low in both the cortex and medulla when compared with the controls. These events indicated that eosinophils and monocytes accumulated in the spleen and thymus after the antigenic stimulation. Furthermore, different frequencies of OPC among the embryonic lymphoid organs showed different responses in the migration of eosinophils and monocytes.

Monocytopoiesis in malignant melanoma: untreated, during immunotherapy and chemoimmunotherapy

Monocytopoiesis and blood monocytes were investigated in patients with superficial spreading melanoma stages I and II. Monocyte production was moderately increased in 4 of 9 untreated patients. Postoperative prophylactic BCG-vaccination gave rise to increased proliferation activity in 3 of 4 patients with previously normal monocytopoiesis. However, monocyte production returned to normal between the 4th and 6th month of BCG immunotherapy. Monocytopoietic hyperproliferation did not occur if DTIC was administered simultaneously with BCG. These results indicate that BCG-vaccination increases monocytopoiesis during the first months of treatment only. This effect is abrogated by concomitant chemotherapy.

Cellular antimicrobial immunity

Acquired resistance to infectious disease may be expressed by a predominantly humoral or a cellular mechanism or, more frequently, by a combination of the two. The cellular interactions which are responsible for the induction of the immune response in the skin, lung, intestinal mucosa, genitourinary tract, conjunctiva, and peritoneal cavity are discussed and the role of living or dead vaccines in the induction of acquired resistance is outlined. The host response involves three different cell types: the phagocytic cell (polymorphs or macrophages), the thymus-dependent (T) lymphocyte, and the thymus-independent (B) lymphocyte-plasma cell line. The normal unstimulated phagocytic cell is capable of killing most nonpathogenic bacteria that gain entry to the tissues. However, the presence of opsonic antibodies and activated macrophages is required to eliminate the pathogenic intracellular parasites. Such immunological activation involves the presence of sensitized T-lymphocytes in the lesion. The cellular response is also characterized by the simultaneous development of a state of delayed-type hypersensitivity (DTH), along with the antimicrobial CMI response. A rising humoral response normally develops subsequently. Killed bacterial cells (except when incorporated into Freund's complete adjuvant) induce the humoral response without the CMI reaction so that such vaccines are not able to fully protect the host against the naturally acquired disease. With the development of cell fractionation methods as well as the identification of distinctive cell surface markers, suspensions of B- and T-cells and macrophages can now be prepared for use in increasingly sophisticated transfer and reconstitution studies. The role of the different cell types in the expression of humoral and cellular immunity has been determined, and the effect of various immunopotentiating and immunosuppressive regimens on the immune system as a whole has been evaluated quantitatively. These studies have led to an appreciation of the role played by suppressor B- and T-cells in the interplay of both humoral and cellular components of the host defense system during the development of immune tolerance, desensitization, anergy, autoimmunity, and the expression of an anamnestic immune response following reinfection.

Monocyte production in Hodgkin's disease and non-Hodgkin's lymphoma

Monocytopoietic proliferation activity was investigated in patients with untreated Hodgkin's disease, Hodgkin's disease in long-term complete remission, and untreated non-Hodgkin's lymphoma of the lymphosarcoma and reticulosarcoma type. Untreated Hodgkin's disease was found to be associated with a rise in medullary monocyte production which returned to normal during long-term complete remissions. In contrast, monocyte production was increased in only 5 out of 14 patients with lymphosarcoma and reticulum cell sarcoma, normal in 3, and reduced in 6. In neither of these lymphomas was any relation between monocyte production and stage or histology of the disease detectable.

Cell kinetics during inflammation

This communication deals with the production and kinetics of mononuclear phagocytes and polymorphonuclear phagocytes in the normal steady state and during an acute inflammatory reaction and with the humoral regulation of the increased production of leucocytes during an inflammatory reaction. The effect of hydrocortisone and azathioprine on both kinds of phagocytic cells is also discussed.

Monocytosis associated with the growth of transplanted syngeneic rat sarcomata differing in immunogenicity

The effect of the growth of two syngeneic transplanted sarcomata of widely differing biological properties on the number of monocytes in the blood of rats was measured (1) by binding of a specific antimacrophage serum to leucocytes, and (2) by sedimenting in a density gradient rosettes between mononuclear cells and antibody-coated sheep red cells under conditions in which B-cells are not brought down. For the 4 syngeneic sarcomata studied there was a progressive increase in the number of monocytes with tumour growth and the values returned to normal a few days after their surgical removal. The extent of monocytosis was related to the immunogenicity of the tumour and was most pronounced for the HSBPA sarcoma, which is highly immunogenic, has a low rate of spontaneous metastasis and contains many macrophages, and least for the MC-3 sarcoma which is essentially non-immunogenic, invariably gives rise to distant metastases and contains only about 8% macrophages. The growth of sarcomata had previously been found to reduce the number of monocytes which enter inflammatory lesions, both non-specific and due to a delayed hypersensitivity reaction. This "anti-inflammatory" action of sarcomata which is related to their immunogenicity cannot be ascribed to the preferential uptake of monocytes by the tumours and it is concluded that the monocytes in the blood of tumour-bearers, though increased in number, are modified so that they do not enter sites of inflammation.

Monocytopoiesis in chronic eczematous diseases, psoriasis vulgaris, and mycosis fungoides

Monocytopoiesis and blood monocytes were examined in 8 patients with disseminated chronic eczematous diseases, 8 patients with disseminated psoriasis vulgaris, and 8 patients with mycosis fungoides in plaque or tumor stage. Monocytopoiesis was moderately stimulated in all these patients. The stimulation manifested itself by: (1) a rise in relative number of promonocytes in bone marrow in all patients with eczema, in 1 out of 8 patients with psoriasis, and in 7 out of 9 examinations in patients with mycosis fungoides; (2) a rise in [3H]thymidine labeling indices of medullar promonocytes (8/8 eczema, 7/7 psoriasis, 8/9 mycosis fungoides); and (3) a rise in the naphthol-AS-D-chloroacetate esterase activity of blood monocytes, indicating premature monocyte marrow egress (3/5 eczema, 7/8 psoriasis, 9/9 mycosis fungoides). In eczema and psoriasis the mean enhancement of monocytopoietic activity was similar but less pronounced than in mycosis fungoides. In the latter disease there was no correlation between measured parameters and visible skin lesions. The results were interpreted as indicative of increased monocyte consumption by pathologic, immunologic, and/or inflammatory processes.