Ion channels in volume regulation of clonal kidney cells

OBJECTIVES

Clonal kidney cells (Vero cells) are extensively utilized in the manufacture of biological preparations for disease diagnostics and therapeutics and also in preparation of vaccines. In all cells, regulation of volume is an essential function coupled to a variety of physiological processes and is a topic of interest. The objective here was to investigate involvement of ion channels in the process of volume regulation of Vero cells.

METHODS

Involvement of ion channels in cell volume regulation was studied using video-microscopy and flow cytometry. Pharmacologically unaltered cells of different sizes, which are presumably at different phases of the cell cycle, were used.

RESULTS

Ion transport inhibitors altered all phases of regulatory volume decrease (RVD) of Vero cells, rate of initial cell swelling, V(max) and volume recovery. Effects were dependent on type of inhibitor and on cell size (cell cycle phase). Participation of aquaporins in RVD was suggested. Inhibitors decelerated growth, arresting Vero cells at the G(0) /G(1) phase boundary. Electrophysiological study confirmed presence of volume-activated Cl(-) channels and K(+) channels in plasmatic membranes of the cells.

CONCLUSION

Vero cells of all sizes maintained the ability to recover from osmotic swelling. Activity of ion channels was one of the key factors that controlled volume regulation and proliferation of the cells.

Humoral immune response of patients bitten by the snake Bothrops erythromelas

INTRODUCTION: Snake envenomings are a health problem in rural areas of tropical and subtropical countries, but little is known regarding the immune response presented by bitten individuals. The IgM production of patients bitten by Bothrops erythromelas snake was analyzed to identify the effectiveness of treatment in this type of envenomation. METHODS: Bothrops erythromelas venom was submitted to electrophoresis and transferred to a nitrocellulose sheet, following incubation with patients' sera. RESULTS: A 38 KDa protein was detected before and 24 h after therapy. CONCLUSIONS: The result suggests that this protein could be used as a marker for individuals envenomed by Bothrops. erythromelas.

Evaluation of memory immune response to mycobacterium extract among household contact of tuberculosis cases

The human immune response to tuberculosis (TB) is especially mediated by T CD4(+)lymphocytes. However, more studies are needed in order to understand the exact role of each cytokine in the mechanisms for cures. In this article, our aim was to analyze the production of TNF-alpha, IL-10, and IFN-gamma in peripheral blood mononuclear cells (PBMCs) among the household contacts of common primary TB cases, with or without histories of active TB infection, who were negative to parasitological and HIV tests. In order to characterize the cytokine production, PBMCs from these groups were stimulated with whole-protein extract of M. tuberculosis (WPE) antigen (rAgTb) for 24 and 48 hr. The culture supernatants were collected and IFN-gamma, TNF-alpha, and IL-10 were assayed using capture ELISA. There were no statistical differences between primary TB cases and their household contacts with or without previous histories of lung TB. Our results suggest that T memory cells, T regulatory cells, and the Th1/Th2 dichotomy may be responsible for the results described in this article. Further studies are currently underway.

Clinical, epidemiological and laboratory aspects of patients with American cutaneous leishmaniasis in the State of Pernambuco

The diagnosis for American cutaneous leishmaniasis is based on an association of clinical, epidemiological and laboratory characteristics. The present study identified the circulating species of Leishmania in the State of Pernambuco, described its clinical-epidemiological characteristics and diagnosed the disease. Nineteen patients presenting active lesions who had been diagnosed through clinical evaluation and laboratory tests were selected. The tests included direct investigation, in vitro culturing, Montenegro skin test, indirect immunofluorescence and polymerase chain reaction. The Montenegro Skin Test showed positive results in 89% of the patients; indirect immunofluorescence, in 79%; direct investigation, in 58%; and polymerase chain reaction in 75%. Seven Leishmania (Viannia) braziliensis samples were isolated from these patients and were characterized by means of specific monoclonal antibodies. These data confirm that a combination of different diagnosis techniques is needed in order to obtain efficient results and that, so far, Leishmania (Viannia) braziliensis is the only species responsible for American cutaneous leishmaniasis infection in Pernambuco. Thus, it is essential to identify the parasite species involved in cases of human disease in an endemic area in order to determine the clinical and epidemiological characteristics, especially with regard to diagnosis, therapy development and disease prognosis.

Immunization with cytoplasmic repetitive antigen and flagellar repetitive antigen of Trypanosoma cruzi stimulates a cellular immune response in mice

In previous studies, we demonstrated that CRA and FRA recombinant proteins, used for diagnosis of Chagas' disease, elicited a humoral immune response in susceptible and resistant mice. To understand better the immune response to these proteins, we have evaluated, the cellular immune response in CRA- and in FRA-immunized BALB/c and C57BL/6 mice. A specific cellular lymphoproliferative response was observed in both strains of mice. Spleen cell cultures mainly from CRA-immunized C57BL/6 and FRA-immunized BALB/c mice produced high levels of IFN-y, indicating the induction of a Type 1 immune response. Regarding the T cell subsets, CD4+ T cells were the major source of IFN-y in CRA- and FRA-immunized mice. These results suggest that CRA and FRA are important immunogens in inducing a Type 1 immune response and that they may be considered as potential vaccine antigens.

[Hematological and histopathological evaluation of BALB/c and C57BL/6 mice exposed to Cytoplasmic Repetitive Antigen and Flagellar Repetitive Antigen recombinant antigens of Trypanosoma cruzi]

The Cytoplasmic Repetitive Antigen and Flagellar Repetitive Antigen recombinant antigens of Trypanosoma cruzi were inoculated into BALB/c and C57BL/6 mice and its effects evaluated at hematological and histopathological levels. The results showed that the histological pattern of the organs and the hematological profile of mice were not modified suggesting that these antigens are not harmful for the animal.

Evaluation of the immune response to CRA and FRA recombinant antigens of Trypanosoma cruzi in C57BL/6 mice

Humoral and cellular immune responses were evaluated in 44 C57BL/6 mice immunized with the Trypanosoma cruzi recombinant antigens CRA and FRA. Both antigens induced cutaneous immediate-type hypersensitivity response. The levels of IgG1, IgG2a, IgG2b and IgG3 were high in CRA immunized mice. IgG3 was the predominant isotype. Although no difference in antibody levels was observed in FRA-immunized mice when compared to control mice, both antigens were able to induce lymphoproliferation in immunized mice. Significant differences were observed between incorporation of [ H]- thymidine by spleen cell stimulated in vitro with CRA or FRA and the control group. These results suggest that CRA and FRA could be involved in mechanisms of resistance to Trypanosoma cruzi infection.

Protective immunity of single and multi-antigen DNA vaccines against schistosomiasis

We evaluated the usefulness of the combination of three plasmids encoding tegumental (pECL and pSM14) and muscular (pIRV5) antigens of the Schistosoma mansoni on improving the protective immunity over the use of a single antigen as DNA vaccines. Female BALB/c mice were inoculated twice with 25 micro g DNA plasmid within two weeks interval. The challenge was performed with 80 cercarias of a regional isolate of S. mansoni (SLM) one week after the last immunization. Six weeks after challenge, all mice were perfused for worm load determination. The following groups were analyzed: saline; empty vector; monovalent formulations of pECL; pSM14 and pIRV5 and also double combinations of pECL/pIRV5 and pIRV5/pSM14 and a triple combination of pECL/pIRV5/pSM14. The protection was expressed as a percentage of worm loads in each group compared with the saline group. The results obtained were 41% (p < 0.05); 52% (p < 0.05); 51% (p < 0.05); 48% (p < 0.05); 55% (p < 0.05); 45% (p < 0.05); 65% (p < 0.05) for each group respectively.