Malaria at Humaita county, Amazonas state, Brazil: XVII — immune response in patients with Plasmodium falciparum according to gametocytes

In August 1983 the Authors studied 36 patients with Plasmodium falciparum malaria and 14 normal individuals born in Humaita region who had never had malaria, had no spleen enlargement and had negative parasitemia as well as passive hemagglutination. Medical histories were obtained and complete physical examination were performed in all of them just as blood tests, parasite density and lymphocyte typing. The lymphocytes were separated and then frozen in liquid nitrogen for later typing by rosette formation. The patients were divided in two groups according to the presence (13 patients) or abscence (23 patients) of gametocytes before treatment. Severe malaria was predominant in the group without gametocytes. The results showed a decrease in the T-cell numbers in Plasmodium falciparum acute malaria patients both with or without gametocytes before the treatment, while B-cell numbers were normal only in the patients with gametocytes. These observations as like as those previously reported by the Authors, permit to associate the presence of gametocytes in peripheral blood and normal number of B-cells in patients with mild Plasmodium falciparum malaria.

Failure of nitric oxide production by macrophages and decrease in CD4+ T cells in oral paracoccidioidomycosis: possible mechanisms that permit local fungal multiplication

Paracoccidioidomycosis is a chronic granulomatous disease that induces a specific inflammatory and immune response. The participation of nitric oxide (NO), a product of the inducible nitric oxide synthase enzyme (iNOS), as an important fungicidal molecule against Paracoccidioides brasiliensis has been demonstrated. In order to further characterize the Oral Paracoccidioidomycosis (OP), we undertook an immunohistochemical study of iNOS+, CD45RO+, CD3+, CD8+, CD20+, CD68+ cells and mast cells. The samples were distributed in groups according to the number of viable fungi per mm². Our results showed weak immunolabeling for iNOS in the multinucleated giant cells (MNGC) and in most of the mononuclear (MN) cells, and the proportion of iNOS+ MN/MNGC cells in the OP were comparable to Control (clinically healthy oral tissues). Additionally, our analysis revealed a similarity in the number of CD4+ cells between the Control and the OP groups with higher numbers of fungi. These findings suggest that a low expression of iNOS and a decrease in the CD4+ T cells in OP may represent possible mechanisms that permit the local fungal multiplication and maintenance of active oral lesions.

Cytokines and dysregulation of the immune response in human malaria

The dysregulation of the immune response by malaria parasite has been considered as a possible constraint to the effectiveness of malaria vaccination. In spite of the important role interleukin-I (IL-1) in malaria are lacking. We found that only 2 out of 35 subjectswith acute malaria showed increased levels of serum IL-1 alpha by enzyme immunoassay. To assess whether IL-1 could interfere with T- lymphocyte responses, blood mononuclear cells from patients infected with Plasmodium falciparum, P. vivax, or healthy subjects were cultured with phytohemagglutinin, and lymphocyte proliferation measured 72h later by 3H-thymidine incorporation. Our data showed that T-lymphocyte responses are depressed both in P. falciparum (10,500 ñ 2,900) and P. vivax malaria (13,000 ñ 3,300), as compared to that of healthy individuals (27,000 ñ 3,000). Addition of IL-1 partially reserved depression of malaria lymphocytes, but had no effect on normal cells. On the other hand, T-lymphocytes from malaria infected-subjects presented a minimal decrease in proliferation, when cultured in the presence of exogenous PGE2. These data indicate the occurrence of two defects of immunoregulation in malaria: a deficiency of IL-1 production by monocytes/macrophages, and an increased resistance of lymphocytes to the antiproliferative effect of PGE2.

15d-PGJ2 modulates acute immune responses to Trypanosoma cruzi infection

The acute phase of Trypanosoma cruzi infection is associated with a strong inflammatory reaction in the heart characterised by a massive infiltration of immune cells that is dependent on the T. cruzi strain and the host response. 15d-PGJ2 belongs to a new class of anti-inflammatory compounds with possible clinical applications. We evaluated the effects of 15d-PGJ2 administered during the acute phase of T. cruzi infection in mice. Mice were infected with the Colombian strain of T. cruzi and subsequently treated with 15d-PGJ2 repeatedly for seven days. The inflammatory infiltrate was examined by histologic analysis. Slides were immunohistochemically stained to count the number and the relative size of parasite nests. Infection-induced changes in serum cytokine levels were measured by ELISA. The results demonstrated that treatment with 15d-PGJ2 reduced the inflammatory infiltrate in the skeletal muscle at the site of infection and decreased the number of lymphocytes and neutrophils in the blood. In addition, we found that 15d-PGJ2 led to a decrease in the relative volume density of amastigote nests in cardiac muscle. T. cruzi-infected animals treated with 15d-PGJ2 displayed a statistically significant increase in IL-10 levels with no change in IFN-γ levels. Taken together, we demonstrate that treatment with 15d-PGJ2 in the acute phase of Chagas disease led to a controlled immune response with decreased numbers of amastigote nests, as measured by the volume density.

Multiple cytokine expression profiles reveal immune-based differences in occult hepatitis B genotype H-infected Mexican Nahua patients

A high prevalence of occult hepatitis B (OHB) genotype H infections has been observed in the native Mexican Nahua population. In addition, a low incidence of hepatitis B virus (HBV)-associated hepatocellular carcinoma has been described in Mexico. The immune response to infection among OHB-infected patients has been poorly evaluated in vivo. Therefore, we assessed the expression profiles of 23 cytokines in OHB genotype H-infected Nahua patients. A total of 41 sera samples from natives of the Nahua community were retrospectively analysed. Based on their HBV antibody profiles, patients were stratified into two groups: OHB patients (n = 21) and patients that had recovered from HBV infection (n = 20). Herein, we report distinctive cytokines profiles in OHB-infected individuals. Compared to healthy controls (n = 20) and patients who resolved HBV infection, OHB-infected patients displayed an increase in interleukin (IL)-2 secretion in addition to a characteristic inflammation profile (decrease in IL-8 and tumour necrosis factor-alpha levels and increased levels of tumour growth factor-beta). IL-15 and interferon-gamma levels were reduced in OHB-infected individuals when compared to those patients who resolved HBV infection. In contrast, OHB patients showed an increase in monocyte chemoattractant protein (MCP)-1 and MCP-2 compared to healthy controls and patients who resolved HBV infection. These findings suggest that cytokine expression can influence the severity of OHB disease and could lead to new investigation into the treatment of liver and other infectious diseases.

Immune and hormonal activity in adults suffering from depression

An association between depression and altered immune and hormonal systems has been suggested by the results of many studies. In the present study we carried out immune and hormonal measurements in 40 non-medicated, ambulatory adult patients with depression determined by CID-10 criteria and compared with 34 healthy nondepressed subjects. The severity of the condition was determined with the Hamilton Depression Rating Scale. Of 40 depressed patients, 31 had very severe and 9 severe or moderate depression, 29 (72.5%) were females and 11 (27.5%) were males (2.6:1 ratio). The results revealed a significant reduction of albumin and elevation of alpha-1, alpha-2 and ß-globulins, and soluble IL-2 receptor in patients with depression compared to the values obtained for nondepressed subjects (P<0.05). The decrease lymphocyte proliferation in response to a mitogen was significantly lower in severely or moderately depressed patients when compared to control (P<0.05). These data confirm the immunological disturbance of acute phase proteins and cellular immune response in patients with depression. Other results may be explained by a variety of interacting factors such as number of patients, age, sex, and the nature, severity and/or duration of depression. Thus, the data obtained should be interpreted with caution and the precise clinical relevance of these findings requires further investigation.

Immune cells and oxidative stress in the endotoxin tolerance mouse model

Sepsis is a systemic inflammatory response that can lead to tissue damage and death. In order to increase our understanding of sepsis, experimental models are needed that produce relevant immune and inflammatory responses during a septic event. We describe a lipopolysaccharide tolerance mouse model to characterize the cellular and molecular alterations of immune cells during sepsis. The model presents a typical lipopolysaccharide tolerance pattern in which tolerance is related to decreased production and secretion of cytokines after a subsequent exposure to a lethal dose of lipopolysaccharide. The initial lipopolysaccharide exposure also altered the expression patterns of cytokines and was followed by an 8- and a 1.5-fold increase in the T helper 1 and 2 cell subpopulations. Behavioral data indicate a decrease in spontaneous activity and an increase in body temperature following exposure to lipopolysaccharide. In contrast, tolerant animals maintained production of reactive oxygen species and nitric oxide when terminally challenged by cecal ligation and puncture (CLP). Survival study after CLP showed protection in tolerant compared to naive animals. Spleen mass increased in tolerant animals followed by increases of B lymphocytes and subpopulation Th1 cells. An increase in the number of stem cells was found in spleen and bone marrow. We also showed that administration of spleen or bone marrow cells from tolerant to naive animals transfers the acquired resistance status. In conclusion, lipopolysaccharide tolerance is a natural reprogramming of the immune system that increases the number of immune cells, particularly T helper 1 cells, and does not reduce oxidative stress.

Suppression of humoral immunity and lymphocyte responsiveness during experimental trypanosoma cruzi infections

C3H/He and C57B1/6 mice were inoculated with 500 Trypanosoma cruzi trypomastigotes (Strain Y). During the acute phase infected mice presented parasitemia and enlargement of lymph nodes and spleens and intracellular parasites were observed in the heart. Examinations of cells derived from spleen and lymph nodes showed increased numbers of IgM and IgG-bearing cells. During the peak of splenomegaly, about day 17 post-infections, splenic lymphocytes showed a marked decrease in responsiveness to T and B-cell mitogens, parasite antigens and plaque forming cells (PFC) to sheep red blood cells (SRBC). Unfractionated or plastic adherent splenic cells from mice, obtained during the acute phase were able to suppress the response to mitogens by lymphocytes from uninfected mice. During the chronic phase. Disappearance of parasitemia and intracellular parasites in the hearts as well as a decrease in spleen size, was observed. These changes preceded the complete recovery of responsiveness to mitogens and T. cruzi antigens by C57B1/6 splenic lymphocytes. However, this recovery was only partial in the C3H/He mice, known to be more sensitive to T. cruzi infection. Partial recovery of humoral immune response also occurred in both strains of mice during the chronic phase.

Specific circulating immune complexes in acute chagas' disease

The presence of circulating immune complexes formed by IgM and IgG (CIC-IgM and CIC-IgG) was investigated, using antigen-specific enzyme-immunoassays (ELISA), in 30 patients with acute Chagas' disease who showed parasitemia and inoculation chagoma. Control population consisted of patients with chronic T. cruzi infection (30), acute toxoplasmosis 10), leishmaniasis (8), rheumatoid arthritis (3) and healthy individuals with negative serology for Chagas* disease (30). Acute chagasic patients were 100% CIC-IgG and 96.66% CIC-IgM positive whereas immunofluorescence tests yielded 90% and 86.66% of positivity for specific IgG and IgM antibodies, respectively. Chronic patients were 68% CIC-IgG and 0% CIC-IgM positive. The 30 negative and the 21 cross-reaction controls proved negative for ELISA (CIC-IgM and CIC-IgG). The high sensitivity of ELISA assays would allow early immunologic diagnosis, as well as prompt treatment, of acute T. cruzi infection, thus eliminating the problem of the false-positive and false-negative results which affects traditional methods for detection of circulating antibodies.

Immunoglobulins and C3 in the P. brasiliensis granuloma

The experimental model of paracoccidioidomycosis induced in mice by the intravenous injection of yeast-forms of P. brasiliensis (Bt2 strain; 1 x 10(6) viable fungi/animal) was used to evaluate sequentially 2, 4, 8, 16 and 20 weeks after inoculation: 1. The presence of immunoglobulins and C3 in the pulmonary granuloma-ta, by direct immunofluorescence; 2. The humoral (immunodiffusion test) and the cellular (footpad sweeling test) immune response; 3. The histopathology of lesions. The cell-immune response was positive since week 2, showing a transitory depression at week 16. Specific antibodies were first detected at week 4 and peaked at week 16. At histology, epithelioid granulomas with numerous fungi and polymorphonuclear agreggates were seen. The lungs showed progressive involvement up to week 16, with little decrease at week 20. From week 2 on, there were deposits of IgG and C3 around fungal walls within the granulomas and IgG stained cells among the mononuclear cell peripheral halo. Interstitital immunoglobulins and C3 deposits in the granulomas were not letected. IgG and C3 seen to play an early an important role in. the host defenses against P. brasiliensis by possibly cooperating in the killing of parasites and blocking the antigenic diffusion.

Cell mediated immune response in human antirabies revaccination

The occurrence of secondary cell mediated immune response (CMI) in human antirabies immunization was studied. The Puenzalida & Palácios vaccine was used because it is routinely used in Brazil. CMI was evaluated by lymphoblastic transformation indices obtained in whole blood culture in the presence of rabies and control (nervous tissue) antigens. Eleven volunteers submitted to revaccination constituted the group under study, while three other volunteers submitted primo vaccination were utilized as control group. A clear secondary CMI to rabies antigen was detected in all the revaccinated volunteers who showed earlier and more intense response than the control group. Response to the control antigen, however, present in all the components of the first group was not detectable in two out of the three primovaccinated and very low in the third one.

Simplification of Immune Adherence Hemagglutination test for detection of rabies antibodies in human serum

In the present work the immune adherence hemagglutination test (IAHA) was standardized in a simplified procedure. This test showed good reproducibility, better than the classical mice serum neutralization test (SN). The tests showed high correlation degree: high titers in one test corresponded to high titers in the other one, and the same occured with low titers. The IAHA test is extremely simple, fast to perform, and of low cost when compared to tests such as SN or indirect immunofluorescense (IIF). It also proved to be useful in less sophisticated laboratories or even as a screening test for the titration of rabies antibodies.

Hepatitis B vaccine - proposal for a standardized assessment of immune response

The authors developed a comparative study of the various methods of assessment of immune response to Hepatitis B vaccine. Eighty-six health care professionals underwent a vaccination programme with three doses of plasma-derived vaccine against Hepatitis B (H-B-Vax, Merck, Sharp & Dohme) given intra-muscularly. Assessment of immune response was carried out three months after the end of the programme, by radioimmunoassay (RIA) and enzymeimmunoassay (EIA). The results showed that the semi-quantitative assessment of Anti-HBs antibodies by RIA or EIA was perfectly comparable to the reference method (quantitative determination of antibodies by RIA). In view of these findings, the authors suggest a standardization of assessment of immune response to the vaccine, thus permitting correct planning of booster doses and easier comparison between different studies