Trypanosoma cruzi infection in mice enhances the membrane expression of low-affinity Fc receptors for IgG and the release of their soluble forms

The membrane expression of low-affinity Fc receptors for IgG (FcγRII/III) on cells and the number of FcγRII/III(+) cells were studied by flow cytometry, using the 2-4G2 MoAb, in mice infected by Trypanosoma cruzi. Cells from spleen, mesenteric lymph nodes and peritoneum were collected on days 10, 20, 30 and 40 post infection (p.i.). The in vivo serum level of soluble FcγRII/III, as well as its in vitro release by cells from infected mice were studied. Parasitaemia and IgG1, IgG2a and IgG2b T. cruzi-specific antibody titres were also recorded. Both the expression of FcγR on cell membrane and the absolute number of FcγR(+) cells increased in spleen and in mesenteric lymph nodes, but not in peritoneum. The modifications in spleen occurred in the early and late parasitaemic phase of infection, i.e., before and after detection of T. cruzi-specific antibodies (from day 10 to 40 p.i.). In mesenteric lymph nodes, the variations were observed only in the early acute infection, when antibodies were not yet detectable at significant levels (on days 10 and 20 p.i.). Higher levels of soluble FcγR were detected in sera and in culture supernatants of spleen and lymph node cells from day 20 to 40 p.i. These results show that T. cruzi infection in mice upregulates the expression and the release of FcγRII/III, in the acute phase of infection, before as well as after the rise of antibody response.     

A Technique to Control the Deleterious Effects of Retrograde Blood Flow and to Improve Myocardial Protection in Surgery of Acute Dissection of the Ascending Aorta

In surgery of the acute dissection of the ascending aorta, a technique is described for routine cannulation through a Dacron graft in order to produce antegrade flow in the true aortic lumen and higher pressures than in the false lumen. This is a useful method to avoid the deleterious effects of the retrograde blood flow through the false lumen, when femoral cannulation is used, as well as to improve the myocardial protection by reperfusing the myocardium while the graft distal end anastomosis is carried out.     

Intermediate filament aggregates in mitoses of primary cutaneous neuroendocrine (Merkel cell) carcinoma

Primary cutaneous neuroendocrine carcinomas express different kinds of intermediate filaments and frequently in a 'paranuclear globular' pattern. We have observed the same pattern not only in interphase but also in mitotic cells, which are very frequent in these tumours. We report a quantitative and morphological study of eight primary cutaneous neuroendocrine carcinomas stained with different antibodies against cytokeratins (CAM 5.2 and anti-cytokeratin 20), neurofilaments (70 kDa and 200 kDa) and peripherin. We have found a predominance of CAM 5.2 expression in interphase cells and of neurofilament proteins in mitotic cells; 87.02% of the interphase cells were positive with CAM 5.2 whereas only 6.08% were positive for neurofilaments ( P <0.01); 35.41% of the mitotic cells were positive with CAM 5.2, whereas 50% were positive for neurofilaments ( P <0.01). A correlation between a globular pattern of intermediate filament proteins and prognosis has not been found. We describe for the first time the division of neoplastic cells with a globular pattern; the presence of intermediate filament proteins with a globular pattern in all mitotic stages; and the uneven distribution of this formation between the two daughter cells.     

Low density lipoprotein receptor expression and function in human polymorphonuclear leucocytes

Low density lipoprotein receptors (LDLR), capable of internalizing LDL, are expressed in polymorphonuclear neutrophils (PMN). The expression was assessed using anti-LDLR antibody by flow cytometry. The internalization of LDL was assessed by: (i) quantification of the uptake of labelled LDL with 1,1′-dioctadecyl-3,3,3′,3′ tetramethyl-indocarboxycyanine perchlorate (DiI) by flow cytometry; and (ii) the binding of LDL-¹²⁵I. In fresh purified cells, Lineweaver–Burk analysis of LDL binding (LDL-DiI) revealed that the calculated Kd (internalized LDL) for PMN (15.0 × 10⁻⁹ m) is lower than the Kd for monocytes (1.1 × 10⁻⁷ m) and the Kd for lymphocytes (3.2 × 10⁻⁷ m). Scatchard analysis (LDL-¹²⁵I) revealed 25 000 binding sites and a Kd of 9.6 × 10⁻⁹ m for PMN. The interaction of LDL with its receptor caused a two-fold fast (peak at 1 min) and transient increase in the oxidative burst, measured by the formation of 2′,7′ dicholoflurescein (DCF) by flow cytometry. This effect was not observed in monocytes or lymphocytes, and it was blocked by anti-LDLR antibody. The stimulation of LDL was optimal at 10 μg of protein/ml. LDL was able to suppress DCF formation induced by phorbol myristate acetate (PMA) and PMA was unable to further stimulate LDL-treated cells, suggesting protein kinase-C (PKC) involvement in LDL effects. Using a PKC assay, LDL was shown to induce a two-fold increase in PKC translocation to the membrane. Thus, LDL increases PMN oxidative burst through a PKC-dependent pathway.     

T-cell cytokine profiles are altered in childhood asthma exacerbation

Background and objective:   Stable asthma is characterized by the production of Th2 cytokines, although Th1 cytokines may play a key role in aspects such as airway hyper-responsiveness. This study explored cytokine profiles associated with asthma exacerbation.
Methods:   Intracellular T-cell cytokine production was measured in 16 children with acute severe asthma (emergency department), after convalescence (6 weeks, n  = 13), with stable disease (after 6 months, n  = 7) and in 14 age-matched hospital controls. Flow cytometry was used to identify CD4+ and CD8+ cells and to quantify intracellular T-cell production of the cytokines interferon (IFN)-γ, IL-4 and IL-13. Cytokine production was compared using analysis of variance and random-effects generalized linear models and associations were examined using Pearson's correlation.
Results:   Cytokine production was evident in CD4+ and CD8+ cells, and compared with asthmatic children, non-asthmatics had a higher percentage of IFN-γ+CD4+ cells ( P  = 0.01). The percentage of CD8+IFN-γ+ cells was increased in the convalescent phase compared with acute ( P  = 0.009) and stable asthma ( P  = 0.004). IL-4+ cells were not significantly altered. IL-13 levels were higher in acute disease than in stable asthma ( P  = 0.009 in CD4+ cells) and IFN-γ/IL-13 ratios indicated a Th2 profile during exacerbation ( P  = 0.005 in CD4+ cells).
Conclusions:   IL-13, rather than IL-4, may play a pro-inflammatory role during acute severe asthma, whereas IFN-γ responses were associated with recovery from acute severe asthma. These results suggest that altered T-cell cytokine profiles may contribute to the pathogenesis of and recovery from asthma exacerbations.