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Query: UMLS:C0026916 (MAC)
 5,226 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of ether, halothane and methoxyflurane (0.5-1.5 MAC) on renal blood flow and its autoregulation were studied in 24 dogs. The left renal artery was perfused with the animals' own blood by a constant pressure perfusion system. The perfusion pressure ranged from 60 to 200 mmHg. Renal blood flow at the perfusion pressure of 100 mmHg was changed neither by ether nor by halothane, while it was decreased dose-dependently by methoxyflurane. At equipotent anesthetic concentrations the autoregulation of renal blood flow was only slightly impaired by ether, but significantly by halothane and methoxyflurane. Adenosine (100 mug/min) or calcium chloride (10 mg/min) which was infused directly into the renal artery resulted in a restoration of autoregulation impaired by MAC-1 of each anesthetic when perfusion pressure was raised stepwise from 100 to 200 mmHg, but no restoration was observed at low perfusion pressure below 100 mmHg. The results indicate that methoxyflurane exerts a direct constrictive effect on the renal vasculature. Adenosine and calcium may play a significant role on the response of the renal vasculature to raised perfusion pressure.
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PMID:Autoregulation of renal blood flow during ether, halothane and methoxyflurane anesthesia in dogs. 84 43

We have previously shown that interleukin-2 (IL-2) is able to induce the generation of natural killer (NK) activity in bone marrow (BM) cell cultures from mice pretreated with 5-fluorouracil (5-FU). Cell fractionation experiments to analyze the nature of BM precursors indicate that MAC-1-, NK1-1- noncytotoxic precursors are induced by IL-2 to proliferate and generate cytolytic NK cells. These data demonstrate that the phenotype and functional characteristics of the IL-2-responsive cells in the FUBM are different from those of mature NK cells in that they are MAC-1+, NK1.1+, CD3- and susceptible to boosting by IFN-alpha.
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PMID:IL-2-dependent generation of natural killer cells from bone marrow: role of MAC-1-, NK1-1- precursors. 153 68

Previously reported studies revealed that extensive immunization with the Methanol Extraction Residue (MER) of BCG tubercle bacillus in Incomplete Freund's Adjuvant (IFA) induced marked suppression of T and B cell functions in vivo and in vitro. The purpose of the present work was to determine whether immunosuppression induced by hyperimmunization with MER is correlated with changes in morphological characteristics and in phenotype pattern of spleen and peritoneal lymphoid cells. Hyperimmunization with MER resulted in a marked increase in the number of spleen cells and in enlargement and granulation of spleen and peritoneal cells. Similar changes in size and granulation were also observed in isolated fractions of splenic T and B cells. Extensive immunization with MER also induced marked decrease in the total number of T cells (Thy 1,2 positive). The decrease in T cells was observed in all three T-cell subsets investigated: Lyt-1, Lyt-2 and L3T4 positive. Although the number of splenic B cells was decreased in samples (10,000 cells), taken from MER hyperimmunized mice, this decrease was compensated by overall increase in the number of spleen cells. The marked decrease in the percentage of splenic T cells was counterbalanced by marked increase in the splenic macrophage population: increase in MAC-1, MAC-2 and MAC-3 positive cells. It is concluded that extensive immunization with MER induces morphological changes in spleen and peritoneal cells, marked decrease in the number of splenic T cells and marked increase of the splenic macrophagic population. It is postulated that these changes are correlated with induction of immunosuppression by a similar procedure of extensive immunization with the agent.
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PMID:Immunosuppression by an immunogenic immunomodulating mycobacterial fraction is correlated to changes in phenotype distribution of murine lymphoid cells. 193 31

Intracerebral inoculation of mice with Theiler's murine encephalomyelitis virus results in an intense inflammatory response of mononuclear leukocytes which infiltrate into the central nervous system. Resistant strains of mice have the ability to clear virus whereas susceptible strains become infected persistently and are associated with chronic demyelination which is proposed to be immune-mediated. In an attempt to better understand the role of the immune response during demyelination, mononuclear leukocytes were isolated from the central nervous system of infected mice and stained by an immunoperoxidase technique with anti-Thy-1.2, anti-L3T4, anti-Lyt-2 and anti-MAC-1 mAb. Infection of susceptible SJL/J mice resulted in a biphasic immune response which peaked on days 7 and 27 post-infection. In contrast, a single peak (day 7) was observed in resistant C57BL/10SNJ mice. The presence of Thy-1.2, L3T4, and MAC-1+ cells was similar between the two strains. However, although the number of Lyt-2+ cells peaked on day 7 in C57BL/10SNJ mice, they were not detected in SJL/J mice until 14 days post-infection and gradually increased in number over the course of infection. To further study the role of T cells in demyelination, serial frozen sections of brain and spinal cord were stained for the presence of Lyt-2 and L3T4+ cells in the lesions of chronically infected SJL/J mice. L3T4+ cells were observed predominantly in perivascular regions while Lyt-2+ cells were observed infiltrating the parenchyma. These results provide further evidence that Lyt-2+ lymphocytes are important in the mechanism of susceptibility/resistance to Theiler's murine encephalomyelitis virus-induced demyelination.
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PMID:Characterization of the inflammatory response in the central nervous system of mice susceptible or resistant to demyelination by Theiler's virus. 249 23

We have previously described a variant murine CTL clone that in contrast to all other clones tested, exhibited a novel capacity to produce IFN-gamma in response to IL-2. This alternative pathway of IFN-gamma induction differed from the conventional TCR complex-mediated pathway in that it was independent of elevated intracellular Ca2+ and insensitive to cyclosporine A. We report here the presence of an analogous pathway in the majority of T lymphocyte clones tested, when these clones are stimulated with IL-2 in the presence of syngeneic or third-party splenocytes. The accessory function of splenocytes in this alternative pathway is mediated by the MAC-1+ subpopulation and apparently involves cell-cell contact. However, the structure with which the MAC-1 antibody reacts probably is not involved directly. No involvement of Ag or the TCR for Ag could be demonstrated in this alternative pathway of lymphokine induction. The array of lymphokines induced by this alternative pathway is only a subset of those induced by antigenic stimulation. Finally, as with the previously described variant clone, IL-2-mediated induction of IFN-gamma production by the normal T lymphocyte clones is independent of normal extracellular Ca2+ levels and insensitive to cyclosporine A. Thus, this alternative pathway of lymphokine induction apparently constitutes a distinct signaling pathway in cloned T lymphocytes.
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PMID:An alternative pathway of induction of lymphokine production by T lymphocyte clones. 249 82

The effector cell in mouse spleen which mediates natural cytotoxicity against mouse hepatitis virus (MHV)-infected target cells was characterized. The target cells were MHV-infected BALB/c 3T3, and the assay time was 3 hr. The effector cell, designated virus killer (VK) cell for the purpose of discussion, had the following phenotype: lymphocyte morphology, plastic-nonadherent, nylon wool-adherent, nonphagocytic, cyclophosphamide-sensitive; by antibody plus complement (C) depletion studies, it was asialo GM1-, NK 1.2 alloantigen-negative, Thy-1.2-, Lyt-5-, and macrophage antigen-negative; by rosetting techniques, it was Fc receptor-positive and surface Fab+; by flow cytometry (FACS) analysis, it was Lyt-2-, MAC-1-, Ia+, IgG (gamma)+, IgM (mu)+, IgD (delta)+, and B cell lineage antibody B-220+. NK cells, measured for cytotoxicity on YAC-1 cells, were similarly tested and were found to differ from the VK cell in the following properties: nylon wool-nonadherent, asialo GM1+, NK alloantigen-positive, Lyt-5+, surface Fab-, MAC-1+, Ia-, IgG-, IgM-, IgD-, and B-220-. The VK effector cell had a phenotype highly distinguishable from NK cells, effectors most commonly associated with antiviral natural cytotoxicity. The VK cell had a phenotype identical to that of a B lymphocyte and was identified as such. Although the effector cells displayed cell surface antibody, the antibody did not appear to be involved in lysis, because lysis could not be blocked by F(ab)'2 directed against Fab, mu, or delta. Cytotoxicity was more likely associated with recognition of the B lymphocyte surface by the MHV glycoprotein E2, as shown in the accompanying companion paper. This is the first demonstration that natural cytotoxicity can be mediated by B lymphocytes.
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PMID:Natural cytotoxicity against mouse hepatitis virus-infected cells. II. A cytotoxic effector cell with a B lymphocyte phenotype. 300 99

Ameboid microglia are isolated from the cerebral tissue of neonatal rat by selective cell adhesion to plastic. Histochemical markers show that the microglial preparations are homogeneous (95 +/- 3%) and represent a 10% yield from starting cultures. Isolated ameboid microglia contain nonspecific esterase activity, the macrophage surface antigens MAC-1 and MAC-3, and acetylated low-density lipoprotein receptors. Ameboid cells have functional properties similar to those of macrophages, including the ability to engulf 5 micron latex beads, to secrete Interleukin-1 (IL-1) and to release superoxide anion. Unlike monocytes and adherent spleen cells, ameboid microglia do not show peroxidase activity by histochemical stain. Unlike resident peritoneal macrophages, ameboid microglia proliferate in vitro. Scanning electron microscopy shows that ameboid cells have short, spinous processes that can be distinguished from the ruffled surfaces of body macrophages. Our observations suggest that ameboid microglia are a distinct class of mononuclear phagocytic cells. Retinoic acid and dimethyl sulfoxide, agents known to accelerate differentiation in vitro, stimulate ameboid cells to develop thin processes several hundred microns in length. These "process-bearing" microglia eventually lose the capacity to engulf latex beads and to proliferate. They also show reductions in nonspecific esterase activity and in the binding of acetylated low-density lipoprotein. We suggest that in vitro ameboid microglia differentiate into nonphagocytic cells similar to ramified microglia found in normal adult brain. The isolation techniques described here provide the opportunity to study the composition and function of different microglial subpopulations during the development of the CNS.
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PMID:Characterization of ameboid microglia isolated from developing mammalian brain. 301 87

Conditioned media of cultured mouse mesangial cells (possessing microfilaments) were shown to contain a factor that stimulated splenic monocytes-macrophages and blood monocytes to replicate. Replicated cells were shown to express MAC-1 antigen as demonstrated by immunofluorescence with anti-MAC 1 and to possess Fc receptors as evidenced by their capacity to ingest sensitized erythrocytes. Preliminary characterization revealed the following characteristics: by Amicon ultrafiltration, fractions greater than 100,000 daltons were shown to have biologic activity; chromatofocusing of these active fractions revealed a peak of activity associated with fractions having pH 4; heating to 100 degrees C for 10 minutes abolished almost all activity, whereas trypsin treatment was without effect. The observations suggest a mechanism by which mesangial cells may modulate the proliferation of monocytes-macrophages that infiltrate the glomerulus in glomerulonephritis.
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PMID:Induction of mouse monocyte-macrophage replication by a mesangial cell-derived factor. 330 3

Frozen sections of normal Balb/c corneas and corneas from Balb/c mice with Klebsiella keratoconjunctivitis were examined for the expression of class I, class II H-2 antigens and MAC-1 antigens using monoclonal antibodies in an immunoperoxidase technique. Class I antigens were readily detected, in both normal and diseased corneas, mainly in the epithelium. Class II (Ia) and MAC-1 antigens were not detected in the normal corneas. However, these two antigens were found mainly in the epithelium and to a lesser extent in the stroma of corneas from keratoconjunctivitis mice. Both normal and diseased corneas were furthermore shown to be peroxidase-. Since Langerhans cells (LC) are Ia+, MAC-1+, and peroxidase- cells, we conclude that although the normal mouse cornea is devoid of these cells, under bacterial infection LC infiltrate the corneal epithelium.
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PMID:Presence of Langerhans cells in the cornea of Klebsiella keratoconjunctivitis mice. 333 23

Normal C3H bone marrow cells were grown 7 days in medium containing L cell-derived colony stimulating factor-1 (CSF-1). During the first 4 days of culture, erythroid and granulocytic cells decreased while macrophages increased exponentially with a doubling time of about 31 hr. Only 0.3% of all cells in the initial bone marrow suspension formed discrete colonies of mononuclear phagocytes, but by day 6 60% of the nonadherent cells were capable of forming macrophage colonies, representing a 200-fold enrichment of the original progenitor population. Using flow cytometry, mononuclear phagocytes obtained after 4 days of culture were separated into two distinct phenotypes based on their autofluorescence. Nonadherent cells were a discrete population of small cells exhibiting low autofluorescence, and the adherent cells were a broad heterogeneous population of large cells exhibiting high autofluorescence. A panel of currently available rat monoclonal antibodies (MABs) against murine hematopoietic cells were used to determine whether unique subsets of macrophages could be resolved. The MABs RA 31B6 and H-11 stained virtually all the nonadherent cells but not adherent cells. The MABs E-2 and 11-4.1 (anti-H-2Kk) stained almost all the adherent cells and demonstrated no significant staining of nonadherent cells. Nearly all the nonadherent and adherent cells were stained by the MABs DNL 4.4 and MAC-1. Additionally, the data suggest that the epitopes for MAC-2 and MAC-3 and gamma 2a Fc receptors develop late in nonadherent progenitor cells as they mature into adherent macrophages.
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PMID:Characterization of subsets of bone marrow-derived macrophages by flow cytometry analysis. 388 46


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