scholarly journals Phagocytosis of Legionella pneumophila is mediated by human monocyte complement receptors.

1987 ◽  
Vol 166 (5) ◽  
pp. 1377-1389 ◽  
Author(s):  
N R Payne ◽  
M A Horwitz
Keyword(s):  
Legionella Pneumophila ◽  
Bacterial Pathogen ◽  
Human Monocyte ◽  
Complement Receptor ◽  
Complement Receptors ◽  
General Role ◽  
Fresh Serum ◽  
Intracellular Multiplication ◽  
Type 3

We have examined receptors mediating phagocytosis of the intracellular bacterial pathogen, Legionella pneumophila. Three mAbs against the type 3 complement receptor (CR3), which recognizes C3bi, inhibit adherence of L. pneumophila to monocytes by 64 +/- 8% to 74 +/- 11%. An mAb against the type 1 complement receptor (CR1), which recognizes C3b, inhibits adherence by 68 +/- 1%. mAbs against other monocyte surface antigens do not significantly influence adherence. Monocytes plated on substrates of L. pneumophila membranes modulate their CR1 and CR3 receptors but not Fc receptors; such monocytes bind 70% fewer C3b-coated erythrocytes and 53% fewer C3bi-coated erythrocytes than control monocytes. Adherence of L. pneumophila to monocytes in nonimmune sera is dependent on heat-labile serum opsonins; adherence is markedly reduced in heat-inactivated serum (84% reduction) or buffer alone (97% reduction) compared with fresh serum. mAbs against CR1 and CR3 receptors also inhibit L. pneumophila intracellular multiplication and protect monocyte monolayers from destruction by this bacterium. This study demonstrates that human monocyte complement receptors, CR1 and CR3, mediate phagocytosis of L. pneumophila. These receptors may play a general role in mediating phagocytosis of intracellular pathogens.

Modulation in the expression of type 1 (CR1/CD35) and type 3 (CR3/CD11b) complement receptors on leukocytes from patients with Visceral leishmaniasis

2020 ◽  
Vol 218 ◽  
pp. 107970
Author(s):  
Cássio Marinho Campelo ◽  
Igor Carvalho Pinheiro ◽  
Bruno de Melo Tavares ◽  
Guilherme Alves de Lima Henn ◽  
Camila Fernandes ◽  
...  
Keyword(s):  
Visceral Leishmaniasis ◽  
Complement Receptors ◽  
Type 3

scholarly journals Diminished Adherence and/or Ingestion of VirulentMycobacterium tuberculosis by Monocyte-Derived Macrophages from Patients with Tuberculosis

1998 ◽  
Vol 5 (5) ◽  
pp. 690-694 ◽  
Author(s):  
J. Zabaleta ◽  
M. Arias ◽  
J. R. Maya ◽  
L. F. García
Keyword(s):  
Flow Cytometry ◽  
Mycobacterium Tuberculosis ◽  
Human Monocyte ◽  
Heat Inactivation ◽  
Microscopical Examination ◽  
Healthy Controls ◽  
Complement Receptors ◽  
Edta Treatment ◽  
Fresh Serum ◽  
Associated Proteins

ABSTRACT The interaction between the macrophage and Mycobacterium tuberculosis is mediated by a variety of macrophage membrane-associated proteins. Complement receptors have been implicated in the adherence of M. tuberculosis to macrophages. In the present work, the adherence and/or ingestion of M. tuberculosis H37Rv to human monocyte-derived macrophages (MDM) from patients with tuberculosis (TB) and healthy controls was measured by microscopical examination, [3H]uracil incorporation, and CFU. The adherence and/or ingestion was enhanced by fresh serum and inhibited by heat inactivation, EDTA treatment, and anti-CR1 and anti-CR3 antibodies. Comparison of MDM from TB patients and healthy controls showed that the former exhibited a significantly decreased capacity to adhere and/or ingest M. tuberculosis, as determined by the number of CFU and 3H incorporation. The expression of CR1 (CD35) and CR3 (CD11b/CD18) on MDM from TB patients and healthy controls, as determined by flow cytometry, did not show significant differences. These results suggest that the lower ingestion of M. tuberculosis by MDM from TB patients is not due to defects in complement receptors, and therefore, there might be other molecules involved in the adherence and/or ingestion process that render MDM from TB patients ingest less mycobacteria than those from healthy controls.

scholarly journals Legionella pneumophila inhibits acidification of its phagosome in human monocytes.

1984 ◽  
Vol 99 (6) ◽  
pp. 1936-1943 ◽  
Author(s):  
M A Horwitz ◽  
F R Maxfield
Keyword(s):  
Legionella Pneumophila ◽  
Sheep Erythrocyte ◽  
Bacterial Pathogen ◽  
Human Monocytes ◽  
E Coli ◽  
The Mean ◽  
Intracellular Multiplication ◽  
Fluorescence Images ◽  
Activated Monocytes ◽  
Quantitative Fluorescence

We used quantitative fluorescence microscopy to measure the pH of phagosomes in human monocytes that contain virulent Legionella pneumophila, a bacterial pathogen that multiplies intracellularly in these phagocytes. The mean pH of phagosomes that contain live L. pneumophila was 6.1 in 14 experiments. In the same experiments, the mean pH of phagosomes containing dead L. pneumophila averaged 0.8 pH units lower than the mean pH of phagosomes containing live L. pneumophila, a difference that was highly significant (P less than 0.01 in all 14 experiments). In contrast, the mean pH of phagosomes initially containing live E. coli, which were then killed by monocytes, was the same as for phagosomes initially containing dead E. coli. The mean pH of L. pneumophila phagosomes in activated monocytes, which inhibit L. pneumophila intracellular multiplication, was the same as in nonactivated monocytes. To simultaneously measure the pH of different phagosomes within the same monocyte, we digitized and analyzed fluorescence images of monocytes that contained both live L. pneumophila and sheep erythrocytes. Within the same monocyte, live L. pneumophila phagosomes had a pH of approximately 6.1 and sheep erythrocyte phagosomes had a pH of approximately 5.0 or below. This study demonstrates that L. pneumophila is capable of modifying the pH of its phagocytic vacuole. This capability may be critical to the intracellular survival and multiplication of this and other intracellular pathogens.

scholarly journals Isolation of complement-fragment-iC3b-binding proteins by affinity chromatography. The identification of p150,95 as an iC3b-binding protein

1985 ◽  
Vol 231 (1) ◽  
pp. 233-236 ◽  
Author(s):  
K J Micklem ◽  
R B Sim
Keyword(s):  
Polymorphonuclear Leucocytes ◽  
Complement Receptors ◽  
Β Subunit ◽  
Homologous Proteins ◽  
Human Spleen ◽  
Bivalent Cations ◽  
Complement Component C3 ◽  
Additional Protein ◽  
Type 3

The proteins from labelled human spleen membranes and polymorphonuclear leucocytes which bind to the iC3b fragment of complement component C3 were prepared by iC3b-Sepharose chromatography in the presence of bivalent cations. Complement receptor type 3(CR3) was eluted from iC3b-Sepharose by removal of bivalent cations. Complement receptors type 1 and 2 (present in spleen but not in polymorphonuclear leucocytes) were sequentially eluted by an NaCl gradient. An additional protein of Mr 135 000 was eluted from iC3b-Sepharose under the same conditions as those used to elute CR3. Preabsorption of the starting material on an anti-(CR3 β-subunit) antibody column before iC3b-Sepharose chromatography removed the α- and β-chains of CR3 and the 135 000-Mr protein. Preabsorption with iC3b-Sepharose before the anti-(CR3 β-subunit) antibody column showed that iC3b binds CR3 and p150,95, the smallest member of the group of three homologous proteins that share the same β-subunit.

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