The different roles of two distinct Fc gamma receptors on guinea pig macrophages in the phagocytosis of sensitized sheep erythrocytes

The functional roles of two distinct types of Fc gamma receptors (Fc gamma 1/gamma 2R specific for both IgG1 and IgG2, and Fc gamma 2R specific for IgG2 alone) on the surface of guinea pig macrophages in the phagocytosis of sensitized sheep erythrocytes (EA) were investigated by the use of two Fab's of monoclonal anti-Fc gamma 1/gamma 2R and anti-Fc gamma 2R antibodies. The binding and subsequent ingestion of IgG1 antibody-sensitized erythrocytes (EA gamma 1) by macrophages were completely inhibited by anti-Fc gamma 1/gamma 2R Fab', indicating that the reactions are mediated only by Fc gamma 1/gamma 2R. On the other hand, the binding and subsequent ingestion of IgG2 antibody-sensitized erythrocytes (EA gamma 2) were substantially inhibited by anti-Fc gamma 2R Fab', but not by anti-Fc gamma 1/gamma 2R Fab'. The inhibitory activities of anti-Fc gamma 2R Fab' were dependent upon the amount of IgG2 antibody bound on erythrocytes; increasing the amount of bound IgG2 antibody from 0.15 to 0.91 micrograms/2 X 10(8) erythrocytes resulted in a decrease in the inhibition of binding of EA gamma 2 by anti-Fc gamma 2R Fab' from 50 to 0%, and also a decrease in the inhibition of ingestion of EA gamma 2 from 100 to 50%.(ABSTRACT TRUNCATED AT 250 WORDS)     

Enhancement of phagocytosis and cytotoxicity in macrophages by tumor-derived IL-18 stimulation

Inoculation of mice with the murine NFSA cell line caused the formation of large tumors with necrotic tumor cores. FACS analysis revealed accumulations of CD11b⁺ cells in the tumors. Microarray analysis indicated that the NFSA cells expressed a high level of the pro-inflammatory factor interleukin-18 (il-18), which is known to play a critical role in macrophages. However, little is known about the physiological function of IL-18-stimulated macrophages. Here, we provide direct evidence that IL-18 enhances the phagocytosis of RAW264 cells and peritoneal macrophages, accompanied by the increased expression of tumor necrosis factor (tnf-α), interleukin-6 (il-6) and inducible nitric oxide synthase (Nos2). IL-18-stimulated RAW264 cells showed an enhanced cytotoxicity to endothelial F-2 cells via direct cell-to-cell interaction and the secretion of soluble mediators. Taken together, our results demonstrate that tumor-derived IL-18 plays an important role in the phagocytosis of macrophages and that IL-18-stimulated macrophages may damage tumor endothelial cells. [BMB Reports 2014; 47(5): 286-291]     

Phenotypic correction of the immune response by L-tyrosine in mice reacting oppositely to sheep erythrocytes

The possibility of transversion of low-reacting mice into high-reacting ones evaluated by the application of the natural immunostimulators. L-tyrosine and thymic polypeptides (taktivin) were compared by their ability for the phenotypical correction of the immune response of the oppositely reacting mice. It was established that under the application of L-tyrosine to oppositely reacting mice the phenotypical correction of the immune response is possible. The dramatic increase in AFC and the AFC-SI secreting IgM is observed in the mice, low-reacting to SRBC in comparison with the high-reacting lines.     

The handling of Listeria monocytogenes by macrophages: the search for an immunogenic molecule in antigen presentation

The activation of T lymphocytes for immunity to the intracellular pathogen Listeria monocytogenes requires that Ia-positive macrophages ingest the bacteria. The subsequent handling of Listeria by macrophages was examined in this report and related to antigen presentation to T cells. Macrophages pulsed with radiolabeled Listeria, besides releasing acid-soluble radioactivity--an indication of extensive catabolism of the Listeria-derived proteins--were also found to release acid-insoluble peptides. The rate of release of the peptides was not markedly affected by treatment with chloroquine, ammonia, or monensin and was independent of the state of activation and the level of Ia expression of the macrophage. The peptides were not associated with fragments of membranes and were represented by several molecular species. Listeria-derived peptides were also found associated with the macrophage plasma membrane. The membrane-associated peptides behaved like integral membrane proteins and could be released by proteases or detergents. Their expression was independent of the dose of Listeria and the level of Ia expression of the macrophage, and their presence could not be inhibited by protease inhibitors or chloroquine. The Listeria peptides released by the macrophages were very weakly immunogenic in a T cell proliferation assay. Purified plasma membranes from Listeria-pulsed macrophages, which contained membrane-associated Listeria peptides, were not immunogenic by themselves but could be reprocessed by additional macrophages to subsequently stimulate T cells. Trypsin treatment of Listeria-pulsed macrophages did not cause a significant reduction in their ability to stimulate T cells. No association was found between Ia molecules and either the membrane-associated or the released peptides with the use of several technical approaches. Hence, after internalization of Listeria, potentially immunogenic material can be found at the cell surface as well as in the culture fluid. The release of soluble peptides is a clear indication that proteins can be recycled after their internalization in vesicles.     

K-Cl cotransport in LK sheep erythrocytes: Kinetics of stimulation by cell swelling

Summary The effects of osmotic cell swelling were studied on the kinetics of Cl-dependent K⁺ influx, K–Cl cotransport, in erythrocytes from sheep of the low K⁺ (LK) phenotype. Swelling 25% stimulated transport by increasing maximum velocity (J _max) 1.5-fold and by increasing apparent affinity for external K (K _o ) nearly twofold. Dithiothreitol (DTT) was shown to be a partial, reversible inhibitor of K–Cl cotransport. It inhibited in cells of normal volume by reducingJ _max more than twofold: apparent affinity for K _o was increased by DTT, suggesting that DTT stabilizes the transporter-K _o complex. Cell swelling reduced the extent of inhibition by DTT:J _max was inhibited by only about one-third in swollen cells, and apparent affinity was only slightly affected. This result suggested that DTT does not act directly on the transporter, but on a hypothetical regulator, an endogenous inhibitor. Swelling relieves inhibition by the regulator, and reduces the effect of DTT. Reducing intracellular Mg²⁺, Mg _o , stimulated cotransport. Swelling of low-Mg²⁺ cells stimulated transport further, but only by raising apparent affinity for K _o nearly threefold:J _max was unaffected. Thus effects of swelling onJ _max and apparent affinity are separable processes. The inhibitory effects of Mg _o and DTT were shown to be additive, indicating separate modes of action. There appear to be two endogenous inhibitors: the hypothetical regulator, which holds affinity for K _o , low; and Mg _o , which affectsJ _max perhaps by holding some transporters in an inactive form. Swelling stimulates transport by relieving both types of inhibition.     

Drug-induced immune tolerance to sheep erythrocytes in mice of different lines]

Immunological tolerance to sheep erythrocytes was induced in mice of the CBA, C57BL/6, CC57BR, C3H, DBA/2 lines by means of combined administration of a high dose of the antigen and cyclophosphamide. The count of 19S antibody-forming cells was determined in the mouse spleen after the test injection of erythrocytes, by local hemolysis in gel. The extent of the tolerance induced proved to depend on the genotype of the animals; mice of the DBA/2 line were found to be most "sensitive" to its induction. There was revealed no correlation between the level of the immunological reactivity to sheep erythrocytes in the intact mice of different lines and the extent of its suppression in tolerance induction     

High sensitivity of the sheep pulmonary vein antrum to acetylcholine stimulation.

Isolation of the pulmonary vein antrum can terminate atrial fibrillation, but the rationale has not been elucidated. In the present study, we show that sheep atrial effective refractory period (ERP) was heterogeneously shortened by acetylcholine administration. After perfusion with 15 muM acetylcholine, the shortest ERP occurred in the pulmonary vein antrum, which was recorded with the standard intracellular microelectrode technique (the ERP results in the pulmonary vein antrum, left atrial posterior wall, roof, free wall and appendage, and right atrial free wall were 52.0 +/- 1.6, 75.1 +/- 2.0, 77.2 +/- 1.7, 85.6 +/- 1.7, 64.3 +/- 2.1, and 90.5 +/- 1.3 ms, respectively; P < 0.05). Immunofluorescent staining revealed that muscarinic type 2 receptors (M(2)R) were also distributed heterogeneously in the atrial myocardium, with the highest density in the antrum (the relative fluorescent intensity results of the M(2)R in the pulmonary vein antrum, left atrial posterior wall, roof, free wall and appendage, and right atrial free wall were 62.64 +/- 2.56, 53.12 +/- 2.76, 51.83 +/- 2.45, 47.90 +/- 2.33, 55.27 +/- 2.08, and 45.53 +/- 2.02, respectively; P < 0.05), which was in accordance with the heterogeneity of ERP distribution. Thus the pulmonary vein antrum is a unique electrophysiological region with high sensitivity to acetylcholine, and its intensive response to acetylcholine is most likely associated with the dense M(2)R distribution of this region. Such an acetylcholine-induced ERP heterogeneity is possibly a substrate for atrial fibrillation and hence one of the potential electrophysiological bases for the isolation therapy.     

Comparative analysis of the anxiety-related behaviors in four inbred mice

An anxiety-related behavior is an emotional response of an organism, which is quantitatively measured by several behavioral paradigms. We employed two most frequently used behavioral tests, the open field and light-dark exploration, to comparatively analyze the anxiety-like behaviors in four inbred mice. For an accurate recording of movement, motion analysis software was developed that acquires a real-time video input to generate a behavioral path. Effects of the strains on the test results were evaluated by ANOVA with the Newman-Keuls post hoc comparison. Eight different behavioral indices, four from each tests, were grouped into two classes; the results of duration, center crossing, transition, rearing, and ambulation indicate strain differences of FVB/N>C57BL/6J>/=BALB/cA>/=CBA/N (I), while stretched-attend posture, peeping, and defecation show the tendency of FVB/N=C57BL/6J相似文献   

Genetic control of sensitivity to experimental adjuvant arthritis in mice of inbred lines

Genetic control over sensitivity to experimental adjuvant arthritis was studied in different strains of inbred, recombinant and congeneic mice. The development of adjuvant arthritis is genetically regulated, with sensitivity to adjuvant arthritis controlled by H62-complex. The genes controlling sensitivity to adjuvant arthritis were shown to be located in (S-region) H-2 system.     

Studies on accessory cells in the adoptive antibody response to sheep erythrocytes in mice

CBA mice irradiated 3 days prior to injection of syngeneic nonadherent spleen cells and high numbers of SRBC contained approximately ten times more splenic direct plaque forming cells than mice irradiated immediately prior to transfer. This was not true of C57B1 mice. Increased responses in the CBA mice were shown to be dependent upon accessory cells (A cells). The results suggest that A cells are affected differently by irradiation in different strains of mice.     

Analysis of the specific 3H-diazepam binding in the brain of inbred mice with differing emotionality

The influence of sodium chloride and gamma-aminobutyric acid (GABA) on H3-diazepam binding in CNS membrane fraction were investigated in C57Bl/6, BALB/c mice and their F1 hybrids. The addition of GABA (1, 10 and 100 microM) elevated the level of radioligand binding with CNS membranes in all the inbred mice in similar manner. The higher stimulating effect of sodium chloride (50, 100 and 150 mM) on the H3-diazepam reception was found in BALB/c mice and F1 hybrids, as compared to C57Bl/6 mice. It has been suggested that membrane-dependent conformational reconstructions of supramolecular receptor complex are the cause of genetic differences in the regulation of H3-diazepam reception by Cl(-)-ionophore.     

Development of pulmonary chlamydia infection in inbred mice lines differentiated by genetically determinated sensitivity to tuberculosis infection

Mice of I/St strain develop severe lung inflammation and die shortly following infection with virulent mycobacteria. The susceptibility does not depend on the Nramp1 gene, as I/St mice carry its resistant allele, but is controlled by little interacting QTL mapped to chromosomes 3, 9, 17. To find out whether the tuberculosis-susceptible I/St mice are susceptible to other intracellular bacteria taxonomically distant pathogen of Chlamydia pneumoniae was studied. Comparison of I/St and TB-resistant A/Sn mice (both Nramp1r) demonstrated that the former were more susceptible to chlamydia, displaying a significantly shortened survival time following challenge (I/St, 9.2 +/- 1.2 days; A/Sn, 22.0 +/- 0 days (p < 0.001)). To estimate the degree of chlamydial multiplication in the lungs, we suggested a quantitative real-time polymerase chain reaction (PCR)-based method which allows enumeration of the parasite's genome equivalents in infected tissue from 1 to 16 days after challenge. The interstrain difference of chlamydia burden in lungs was observed only after 24 hours after infection. Multiplication of chlamydia in the lungs was controlled efficiently after day 4 of infection. The numbers of genome equivalents dropped slightly by day 8 both in I/St and A/Sn mice. Lung pathology develops more rapidly in I/St compared to A/Sn mice following infection with chlamydia despite their similar ability to control bacterial multiplication. Lung tissue of susceptible I/St mice was markedly infiltrated with macrophages (p < 0.01), which differed significantly from the lungs of resistant A/Sn mice. In agreement with higher macrophage content in the lungs, significantly more macrophage-derived proinflammatory cytokines TNF-? and IL-6 were detected in lung tissue homogenates obtained from I/St mice (p < 0.05). Because the prominent difference in survival time did not correlate with permanent difference in bacterial multiplication, we suggested that both infections trigger fatal pathological processes whose dynamics depends strongly upon the host genetics.