Phenotypic differentiation patterns of the human monocyte/macrophage system

Equine macrophage identification with an antibody (Ki-M6) to human CD68 and a new monoclonal antibody (JB10)

Monoclonal antibodies (mAbs) recognizing equine macrophages are scarce. The present study compared the immunocytochemical staining of various equine tissues (lymphoid tissue, lung, liver, small intestine, skin and blood leucocytes) by an antibody, Ki-M6, which detects CD68 in human macrophages and dendritic cells, and by a new anti-equine mAb, JB10, with staining produced by two previously described anti-equine macrophage mAbs, CZ2.2 and CZ3.3. Ki-M6 was shown to identify equine macrophages, which had a distribution different from those identified by CZ2.2 and CZ3.3. JB10 identified equine macrophages with a distribution similar to those identified by Ki-M6, but additionally bound to polymorphonuclear leucocytes. Flow cytometry of peripheral blood leucocyte subpopulations and tissue immunocytochemistry were used to compare staining by JB10 with that of CZ2.2 and CVS19; the latter identifies the myeloid antigen, EqCD13, found on polymorphonuclear leucocytes. The staining by JB10 differed from that of both CZ2.2 and CVS19, suggesting that JB10 detects a different molecule. These additional mAbs should prove useful for the future study of new, defined, populations of macrophages in equine immune responses and pathology, and, in the case of Ki-M6 antibody, may make possible an analysis of the structure, distribution and function of the CD68 molecule in the horse.

Human resident peritoneal macrophages: phenotype and biology

Macrophages represent the primary line of host defences in the peritoneal cavity. In order to study the metabolic activity and maturation stage of human resident peritoneal macrophages (PM phi). peritoneal fluid (PF) was taken by Douglas puncture from healthy hyperstimulated infertile women undergoing oocyte retrieval for in vitro fertilization. Peritoneal fluid and macrophage culture fluids were studied for different inflammatory mediators such as interleukin-1 (IL-1), tumour necrosis factor (TNF) and interleukin-6 (IL-6). The level of macrophage colony-stimulating factor (M-CSF), which represents a macrophage proliferation and differentiation factor, was determined in the PF and in the serum. Furthermore, the macrophage phenotypic profile was analysed, in particular the expression of sex steroid hormone receptors. IL-1. IL-6 and TNF were detectable in the PF and in the culture supernatants of PM phi whether stimulated or not by IFN-gamma and LPS. The mean level of M-CSF in the PF was 6.37 +/- 2.02 ng/ml as measured by RIA; this level did not correlate with the concentration of PM phi. The mean PF-M-CSF level was 1.4-fold higher than in the sera as measured by a EIA. Oestrogen and progesterone receptors could not be demonstrated on the PM phi analysed, so that a direct relationship between the ovarian steroid concentration in these women and the function of PM phi was unlikely. As compared to peripheral blood monocytes (Mo). PM phi showed a phenotypic profile, with some more mature features, e.g. increased expression of CD14, CD68, FcRII, FcRIII, CR3, CR4 and MHC class II determinants. These results indicate that resident PM phi have acquired in vivo a certain differentiation and/or activation state under micro-environmental factors where cytokines secreted by the M phi themselves or by other cells such as the mesothelium may play important roles.

Joint occurrence of collagen mRNA containing cells and macrophages in human atherosclerotic vessels

Cells with enhanced levels of collagen type I and III mRNA were identified and localized in frozen tissue sections from samples of human atherosclerotic renal and common iliac arteries by in situ hybridization using complementary 35S-labeled RNA probes. Serial sections were immunohistochemically stained for smooth muscle cells, monocytes, and differentiated macrophages. In the fibromuscular intima and in the fibrous plaques, cells with enhanced transcriptional activity were located mainly in the vicinity of differentiated macrophages. In three patients, lack of enhanced transcriptional activity in a proliferated intima was connected with complete absence of macrophages, thus indicating a quiescent stage of atherosclerosis. Immunohistochemical staining of serial sections for smooth muscle cells (SMC) revealed the presence of this cell type throughout the proliferated intima in atherosclerotic arteries including those areas in which enhanced collagen mRNAs were detected. The present results support the idea that macrophages play an important role in the activation of collagen synthesis in SMC of atherosclerotic vessel walls.

Induction of antigen expression of follicular dendritic cells in a monoblastic cell line. A contribution to its cellular origin

Experiments were carried out to elucidate the cellular origin of the dendritic reticulum cell (DRC). The monoblastic cell line THP-1, the histiocytic cell line U-937, and the mononuclear cell fraction from peripheral blood (PMC) were stimulated with supernatants from lectin-stimulated peripheral blood lymphocytes and from stimulated T- and B-cell lines. Differentiation towards DRC was assessed by immunocytochemical demonstration of the DRC-specific antigen Ki-M4. Supernatants from isolated peripheral T lymphocytes and from T- and B-cell lines were capable of stimulating THP-1 to Ki-M4 antigen expression, whereas U-937 and the PMC fraction remained negative for this antigen throughout the experiments. These results provide further evidence for a relationship of DRCs with the mononuclear-phagocytic cell system and hence for their bone marrow origin. Furthermore, the data suggest that soluble factors of T and/or B cells are involved in mediating the differentiation process of precursor cells to DRC.

Culture medium oxygen tension affects fibronectin production in human adult and cord blood macrophages

Varying culture medium oxygen tension from one-half to twice the normal concentration did not alter adult or cord blood monocyte-derived macrophage secretion of lysozyme or total protein. Lowering oxygen tension did result in significant increases in fibronectin concentration in both adult and cord blood macrophage culture supernatants. Dexamethasone (10(-7) M) completely blocked adult macrophage but had no effect on cord blood macrophage fibronectin release in response to lowering oxygen tension. These results indicate that human macrophages selectively regulate fibronectin production in response to changes in oxygen tension in vitro.

HLA class II sublocus expression in benign and malignant breast epithelium

Using immunohistochemistry and a panel of five monoclonal antibodies, the epithelial expression of HLA class II sublocus products by benign and malignant breast has been studied. The magnitude of the stromal mononuclear inflammatory cell infiltrate was assessed. There was expression of HLA class II by 75 per cent of epithelial cells in the benign tissues, with little variation in intensity and between antibodies. There was coordinate expression of DR and DQW1. Epithelial expression by carcinomas was more complex and variable. Most (61 per cent) carcinomas exhibited variable loss of epithelial expression of class II products, as detected by three antibodies recognizing epitopes on DP, DQ, and DR together. Thirteen (28 per cent) carcinomas were completely negative or had very occasional positive cells. The extent of this loss was unrelated to the magnitude of the inflammatory infiltrate and axillary lymph node status. No well-differentiated carcinomas exhibited complete loss. Furthermore, non-coordinate expression of DR and DQW1 was present in 8 out of 40 carcinomas, with the proportion of DQW1 positive epithelium always being less than that of DR. Carcinomas exhibiting non-coordinate expression were never well differentiated; there was no relationship with the extent of the inflammatory infiltrate. This is the first study to detail HLA class II expression in breast, and our results suggest that alterations in expression of these products may modify or reflect tumour behaviour.

Increased release of free oxygen radicals by phagocytosing and nonphagocytosing cells from patients with active pulmonary sarcoidosis as revealed by luminol-dependent chemiluminescence

Oxidative metabolism in phagocytes such as granulocytes, monocytes, and alveolar macrophages is becoming of increasing interest in efforts to determine the pathogenetic mechanisms in diseases related to tissue damage, e.g., sarcoidosis. The release of free oxygen radicals is dependent on the activation of the oxidative metabolism and can be measured by means of chemiluminescence. Basic luminol-dependent chemiluminescence released by monocytes and alveolar macrophages from 12 patients with untreated pulmonary sarcoidosis stage II was increased (p less than 0.01) compared with 12 control subjects. A less distinct difference could be observed in the chemiluminescence response of granulocytes (P less than 0.05). After stimulation with zymosan, alveolar macrophages and monocytes (P less than 0.01) as well as granulocytes (P less than 0.05) had an enhanced luminol-dependent chemiluminescence compared with the control group. Emission of chemiluminescence by alveolar macrophages was considerably lower than that of granulocytes and monocytes. No significant correlation could be demonstrated between chemiluminescence response of granulocytes and monocytes and cellular markers of sarcoidotic activity such as lymphocytosis in bronchoalveolar lavage and T-helper/T-suppressor ratio in the lavage fluid. In contrast to that, a significant correlation (P less than 0.01) could be observed both between nonstimulated chemiluminescence and stimulated chemiluminescence and lymphocytosis and T-helper/T-suppressor ratio in bronchoalveolar lavage. Enhanced chemiluminescence may indicate inflammatory activation in pulmonary sarcoidosis.

An improved method for elimination of mycoplasmas from cell cultures

Cell lines infected by different species of mycoplasma (Mycoplasma orale, Mycoplasma hominis) were decontaminated by co-culture with human blood monocyte (BM)-derived macrophages and pooled human immunoglobulin preparations. Co-cultures with BM-derived macrophages or murine peritoneal macrophages (PM) alone were not successful. The phenotype of infected cell lines did not differ from that of uninfected cell lines as revealed by morphological, enzymecytochemical, and immunocytochemical analysis.

Immunohistochemical analysis of HLA antigens and mononuclear infiltrates of benign and malignant breast

Using immunohistochemistry, the epithelial expression of HLA Class I and II antigens (and beta 2 microglobulin) was compared in benign and malignant breast, and the stromal lympho-histiocytic infiltrate of these tissues quantified. The findings were compared with certain characteristics of the carcinomas. In contrast to other studies, malignancy was found to be associated with a far greater infiltrate of both lymphocytes and macrophages. In carcinomas, lymphocyte but not macrophage numbers showed a positive correlation with epithelial HLA ABC and HLA DR expression. This was particularly striking for T lymphocytes, and especially for the T4 subset. The histological grade of carcinoma is closely related to the degree of HLA ABC and beta 2 microglobulin expression, but no such relationship was found for HLA DR. There were greater numbers of mononuclear cells in the poorer differentiated tumours compared with other grades. Those carcinomas with evidence of lymph node metastasis contained greater numbers of macrophages identified by the antibody Y1/82A, but none of the other parameters studied was found to be associated with local lymph node status. The use of a large panel of monoclonal antibodies against various cellular subtypes has allowed a more detailed analysis of the interaction between breast epithelium and the host response.