Macrophages are strategically located throughout the body tissues, where they ingest and process foreign materials, dead cells and debris and recruit additional macrophages in response to inflammatory signals They are highly heterogeneous cells that can rapidly change their function in response to local microenvironmental signals In this Review, we discuss the four stages of orderly inflammation mediated by macrophages: recruitment to tissues; differentiation and activation in situ; conversion to suppressive cells; and restoration of tissue homeostasis We also discuss the protective and pathogenic functions of the various macrophage subsets in antimicrobial defence, antitumour immune responses, metabolism and obesity, allergy and asthma, tumorigenesis, autoimmunity, atherosclerosis, fibrosis and wound healing Finally, we briefly discuss the characterization of macrophage heterogeneity in humans

/pdf/protective-and-pathogenic-functions-of-macrophage-subsets-5d5nlezyqd.pdf

Protective and pathogenic functions of macrophage subsets

Despite extensive laboratory investigations in patients with respiratory tract infections, no microbiological cause can be identified in a significant proportion of patients. In the past 3 years, several novel respiratory viruses, including human metapneumovirus, severe acute respiratory syndrome (SARS) coronavirus (SARSCoV), and human coronavirus NL63, were discovered. Here we report the discovery of another novel coronavirus, coronavirus HKU1 (CoV-HKU1), from a 71-year-old man with pneumonia who had just returned from Shenzhen, China. Quantitative reverse transcription-PCR showed that the amount of CoV-HKU1 RNA was 8.5 to 9.6 10 6 copies per ml in his nasopharyngeal aspirates (NPAs) during the first week of the illness and dropped progressively to undetectable levels in subsequent weeks. He developed increasing serum levels of specific antibodies against the recombinant nucleocapsid protein of CoV-HKU1, with immunoglobulin M (IgM) titers of 1:20, 1:40, and 1:80 and IgG titers of <1:1,000, 1:2,000, and 1:8,000 in the first, second and fourth weeks of the illness, respectively. Isolation of the virus by using various cell lines, mixed neuron-glia culture, and intracerebral inoculation of suckling mice was unsuccessful. The complete genome sequence of CoV-HKU1 is a 29,926-nucleotide, polyadenylated RNA, with GC content of 32%, the lowest among all known coronaviruses with available genome sequence. Phylogenetic analysis reveals that CoV-HKU1 is a new group 2 coronavirus. Screening of 400 NPAs, negative for SARS-CoV, from patients with respiratory illness during the SARS period identified the presence of CoV-HKU1 RNA in an additional specimen, with a viral load of 1.13 10 6 copies per ml, from a 35-year-old woman with pneumonia. Our data support the existence of a novel group 2 coronavirus associated with pneumonia in humans.

/pdf/characterization-and-complete-genome-sequence-of-a-novel-1jkquzz2br.pdf

Characterization and Complete Genome Sequence of a Novel Coronavirus, Coronavirus HKU1, from Patients with Pneumonia

Molecular cloning and expression of human Tumor-associated Polymorphic Epithelial Mucin

Deficiency of the GPI anchor caused by a somatic mutation of the PIG-A gene in paroxysmal nocturnal hemoglobinuria.

Identity of the Epstein-Barr virus (EBV) receptor with the complement receptor type 2 (CR2) was established in three sets of experiments using the monoclonal antibodies, HB-5 and anti-B2, which recognize a Mr 145,000 B-lymphocyte membrane protein that is CR2. First, the rank order for binding of fluoresceinated EBV to four lymphoblastoid cell lines (SB, JY, Raji, and Molt-4) was identical to the rank order for binding of HB-5 and anti-B2 by analytical flow cytometry. Second, pretreatment of cells with HB-5 followed by treatment with goat F(ab')2 fragments to mouse IgG blocked binding of fluoresceinated EBV on SB, a B-lymphoblastoid cell line. Virus attachment was not inhibited by HB-5 alone, second antibody alone, rabbit anti-C3b receptor, or UPC10 (an irrelevant monoclonal antibody). Third, transfer of CR2 from SB to protein A-bearing Staphylococcus aureus particles, to which HB-5 had been absorbed, conferred on them the specific ability to bind 125I-labeled EBV. We conclude that CR2 is the EBV receptor of human B lymphocytes.

https://www.pnas.org/content/pnas/81/14/4510.full.pdf

Epstein-Barr virus receptor of human B lymphocytes is the C3d receptor CR2.

Decay-accelerating factor (DAF) is a 70,000 Mr protein that has been isolated from the membrane of red cells. The function of DAF is to inhibit the assembly of amplifying enzymes of the complement cascade on the cell surface, thereby protecting them from damage by autologous complement. We raised monoclonal antibodies to DAF and used them to study its distribution in cells from the peripheral blood of normal individuals and of patients with paroxysmal nocturnal hemoglobinuria (PNH), a disease characterized by the unusual susceptibility of red cells to the hemolytic activity of complement. The results of immunoradiometric assays and of fluorescence-activated cell sorter analysis showed that DAF was present not only on red cells but was widely distributed on the surface membrane of platelets, neutrophils, monocytes, and B and T lymphocytes. By Western blotting, we observed small but consistent differences in the Mr of DAF from the membranes of various cell types. Quantitative studies showed that phagocytes and B lymphocytes, which presumably enter more frequently in contact with immune complexes and other potential activators of complement, had the highest DAF levels. As previously reported by others, the red cells from PNH patients were DAF deficient. When the patients' red cells were incubated in acidified serum (Ham test), only the DAF-deficient cells were lysed. In addition, we detected defects in DAF expression on platelets and all types of leukocytes. The observed patterns of DAF deficiency in these patients were consistent with the concept that the PNH cells were of monoclonal origin. In one patient, abnormal and normal cells were found only in the erythroid, myeloid, and megakaryocytic lineages. In two other patients, the lymphocytes were also DAF deficient, suggesting that a mutation occurred in a totipotent stem cell. It appears, therefore, that the lesion leading to PNH can occur at various stages in the differentiation of hematopoietic cells.

/pdf/distribution-of-decay-accelerating-factor-in-the-peripheral-1vwpthj1ry.pdf

Distribution of decay-accelerating factor in the peripheral blood of normal individuals and patients with paroxysmal nocturnal hemoglobinuria.

Protective immunity against malaria can be obtained by vaccination with irradiated sporozoites. The protective antigens known as circumsporozoite (CS) proteins, are polypeptides that cover the surface membrane of the parasite. The CS proteins contain species-specific immunodominant epitopes formed by tandem repeated sequences of amino acids. Here it is shown that the dominant epitope of Plasmodium falciparum is contained in the synthetic dodecapeptide Asn-Ala-Asn-Pro-Asn-Ala-Asn-Pro-Asn-Ala-Pro or (NANP)3. Monoclonal antibodies and most or all polyclonal human antibodies to the sporozoites react with (NANP)3, and polyclonal antibodies raised against the synthetic peptide (NANP)3 react with the surface of the parasite and neutralize its infectivity. Since (NANP)3 repeats are present in CS proteins of P. falciparum from many parts of the world, this epitope is a logical target for vaccine development.

https://science.sciencemag.org/content/sci/228/4706/1436.full.pdf

Rationale for Development of a Synthetic Vaccine Against Plasmodium falciparum Malaria

Sheep red cells (E) sensitized with IgG antibody (EA) or with antibody and complement (EAC) interact in vitro with mouse peritoneal macrophage monolayers. The role of IgG and of C3 in the attachment and ingestion of the erythrocytes was examined by means of quantitative technique utilizing (51)Cr-labeled E. Controlled osmotic lysis permitted the separate measurement of the radioactivity associated with bound or with ingested E. IgG-(125)I was used to estimate the number of IgG molecules bound per E as a function of the IgG concentration. Control experiments showed that iodination did not influence the extent of binding of IgG to E and that the binding of IgG prepared from immune serum could be essentially ascribed to its anti-E antibody content. Only between 10(3) and 10(4) rabbit anti-E IgG molecules per erythrocyte were needed for detectable attachment and ingestion of EA (a maximum number of 6 x 10(5) IgG antibody molecules could be accomodated on one erythrocyte). Evidence was obtained that C3 is primarily involved in particle attachment, whereas only IgG is able to markedly promote the ingestion of particles attached to macrophages: (a) Addition of complement to the EA substantially increased the binding to the macrophages, whereas ingestion was increased to a smaller extent. Both binding and ingestion of EAC were markedly inhibited by papain fragments of IgG obtained from a rabbit antiserum to mouse C3. (b) Low doses (2 microg/ml) of papain fragments of IgG from a rabbit antiserum to mouse IgG markedly reduced the ingestion of EAC, whereas attachment of EAC to macrophages was inhibited to a much smaller degree. The possible relevance of these findings for the in vivo fate of particulate immune complexes as they interact with macrophages is discussed. It is suggested that in the primary immune response, when the complexes are predominantly in the form of EA (IgM) or EA (IgM) C3, they would tend to remain on the surface of the macrophages and thus be in a position to stimulate immunocompetent cells. In the secondary response, when EA (IgG) or EA (IgG) C3 predominate, the complexes would tend to be more rapidly interiorized and degraded by the mononuclear phagocytes,

/pdf/phagocytosis-of-immune-complexes-by-macrophages-different-3z1ggb6opo.pdf

Phagocytosis of immune complexes by macrophages different roles of the macrophage receptor sites for complement (c3) and for immunoglobulin (igg)

A specific DNA probe was used to study the effect of recombinant rat, mouse, and human gamma-interferon (gamma-IFN) on the course of sporozoite-induced malaria infections. In mice and rats infected with sporozoites of Plasmodium berghei, mouse and rat gamma-IFN's strongly inhibited the development of the exoerythrocytic forms in the liver liver cells of the hosts, but not the development of the erythrocytic stages. The degree of inhibition of the exoerythrocytic forms was proportional to the dose of gamma-IFN administered, but was independent of the number of sporozoites used for challenge. A 30 percent reduction in the development of exoerythrocytic forms in rat liver was achieved when 150 units (about 15 nanograms of protein) of rat gamma-IFN were injected a few hours before sporozoite challenge; the reduction was 90 percent or more with higher doses of gamma-IFN. The effect was less pronounced if the gamma-IFN was administered 18 hours before or a few hours after challenge. Human gamma-IFN also diminished the parasitemia in chimpanzees infected with sporozoites of the human malaria parasite Plasmodium vivax. The target of gamma-IFN activity may be the infected hepatocytes themselves, as shown by in vitro experiments in which small doses of the human lymphokine inhibited the development of exoerythrocytic forms of Plasmodium berghei in a human hepatoma cell line. These results suggest that immunologically induced interferon may be involved in controlling malaria infection under natural conditions.

https://science.sciencemag.org/content/sci/232/4752/881.full.pdf

Inhibition of development of exoerythrocytic forms of malaria parasites by gamma-interferon

C4-binding protein (C4-bp), a new component of the complement system, was isolated from human plasma by precipitation with polyethyleneglycol, followed by chromatography on ion exchangers. C4-bp was identified on sodium dodecyl- sulfate polyacrylamide gel electrophoresis (SDS-PAGE) by two independent criteria: its ability to bind to C4b, and immunoprecipitation with a monospecificantiserum. Purified C4-bp is a 10.7 s glycoprotein. It consists of several disulfide bonded subunits of mol wt 70,000 daltons. Under nonreducing conditions, its mol wt has been estimated on SDS-PAGE as 540- 590,000 daltons. C4-bp moves as a slow B-globulin at pH 8.6 in the absence of free divalent cations, but when the buffers contain Ca(++)-lactate, C4-bp is a gamma globulin. Purified C4-bp binds to purified C4b. The reaction proceeds in the presence or absence of divalent cations and is not inhibited by diisopropylfluorophosphate. The C4b/C4-bp complexes have sedimentation coefficients between 15 and 17 s on sucrose gradient ultracentrifugation, and can be readily identified by crossed immunoelectrophoresis (CIE). The complexes move faster toward the anode than either protein. C4-bp is multivalent. Saturation is reached at molecular ratios of C4b/C4- bp of between 4 and 5. The interaction between C4b and C4-bp may complicate the electrophoretic patterns of these proteins in normal human serum, if the complement system is activated before or during the run. However, in EDTA-plasma, native C4 and C4-bp do not form stable complexes and can be identified in separate peaks after CIE.

https://rupress.org/jem/article-pdf/148/1/207/1089275/207.pdf

V Nussenzweig

Papers

Distribution of decay-accelerating factor in the peripheral blood of normal individuals and patients with paroxysmal nocturnal hemoglobinuria.

Rationale for Development of a Synthetic Vaccine Against Plasmodium falciparum Malaria

Phagocytosis of immune complexes by macrophages different roles of the macrophage receptor sites for complement (c3) and for immunoglobulin (igg)

Inhibition of development of exoerythrocytic forms of malaria parasites by gamma-interferon

Human C4-binding protein. I. Isolation and characterization