Reconstitution of CD4+ T cell responses in HIV-1 infected individuals initiating highly active antiretroviral therapy (HAART) is associated with renewed interleukin-2 production and responsiveness

Reconstitution of functional CD4(+) T cell responsiveness to in vitro stimuli is associated with continuous highly active antiretroviral therapy (HAART). Thirty-six antiretroviral naive patients received HAART over 16 weeks. Antigen-specific, mitogen and interleukin (IL)-2 induced lymphocyte proliferative responses and specific IL-2 and IL-4 production were assessed at each time-point, together with quantification of HIV-1 RNA load and lymphocyte populations. Reconstitution of recall responses was limited largely to persistent antigens such as Herpes simplex virus and Candida, rather than to HIV-1 or neo-antigens. Recall antigens, mitogens and IL-2-induced renewed responses were associated with in-vitro production of IL-2, but not IL-4. Differential responsiveness to low versus high concentration IL-2 stimulus increases in a stepwise manner, suggesting normalization of IL-2 receptor expression and improved functionality. These increases in in-vitro proliferative responses thus probably reflect short lived effector clones, driven by ongoing antigenic stimulus associated with persisting long-term organisms. In this context non-responsiveness to HIV-1 antigens suggests ongoing HIV-1 specific clonal T cell anergy.     

Soluble factors released by Toxoplasma gondii-infected astrocytes down-modulate nitric oxide production by gamma interferon-activated microglia and prevent neuronal degeneration

The maintenance of a benign chronic Toxoplasma gondii infection is mainly dependent on the persistent presence of gamma interferon (IFN-gamma) in the central nervous system (CNS). However, IFN-gamma-activated microglia are paradoxically involved in parasitism control and in tissue damage during a broad range of CNS pathologies. In this way, nitric oxide (NO), the main toxic metabolite produced by IFN-gamma-activated microglia, may cause neuronal injury during T. gondii infection. Despite the potential NO toxicity, neurodegeneration is not a common finding during chronic T. gondii infection. In this work, we describe a significant down-modulation of NO production by IFN-gamma-activated microglia in the presence of conditioned medium of T. gondii-infected astrocytes (CMi). The inhibition of NO production was paralleled with recovery of neurite outgrowth when neurons were cocultured with IFN-gamma-activated microglia in the presence of CMi. Moreover, the modulation of NO secretion and the neuroprotective effect were shown to be dependent on prostaglandin E(2) (PGE(2)) production by T. gondii-infected astrocytes and autocrine secretion of interleukin-10 (IL-10) by microglia. These events were partially eliminated when infected astrocytes were treated with aspirin and cocultures were treated with anti-IL-10 neutralizing antibodies and RP-8-Br cyclic AMP (cAMP), a protein kinase A inhibitor. Further, the modulatory effects of CMi were mimicked by the presence of exogenous PGE(2) and by forskolin, an adenylate cyclase activator. Altogether, these data point to a T. gondii-triggered regulatory mechanism involving PGE(2) secretion by astrocytes and cAMP-dependent IL-10 secretion by microglia. This may reduce host tissue inflammation, thus avoiding neuron damage during an established Th1 protective immune response.     

Immunohistochemical study of the expression of MUC5AC and MUC6 in breast carcinomas and adjacent breast tissues

AIM: To study the protein expression patterns of MUC5AC and MUC6 in normal and diseased breast tissues and to compare their expression with that of a mucin (MUC1) normally expressed in mammary tissues. METHODS: Formalin fixed, paraffin wax embedded tissue from 69 cases of invasive breast carcinoma and surrounding breast tissue was studied immunohistochemically with monoclonal antibodies against MUC1 (SM3), MUCSAC (CLH2), and MUC6 (CLH6), using the avidin-biotin-peroxidase method. RESULTS: MUC5AC was detected in five of 68 cases of invasive carcinoma including one of three cases of pure colloid carcinoma. MUCSAC expression in the adjacent normal breast epithelium was present in one of 29 cases and in one of two cases of ductal carcinoma in situ. None of 15 cases of ductal hyperplasia without atypia was positive for MUCSAC. MUC6 was present in 15 of 65 cases of invasive carcinoma, in four of 29 cases of normal adjacent epithelium, two of 15 cases of ductal hyperplasia without atypia, and one of two cases of ductal carcinoma in situ. MUC1 immunoreactivity detected by the SM3 antibody was present in 50 of the 67 cases of invasive carcinoma, but expression was also detected in benign epithelium. All invasive carcinomas expressing MUCSAC were positive for MUC1 and four were positive for MUC6. No significant association was found between the expression of these mucins and tumour size, histological grade, node status, oestrogen receptor status, p53 positivity, or c-ErbB-2 overexpression. CONCLUSIONS: This study documents the expression of two different mucins (MUCSAC and MUC6) not described as being expressed by normal breast tissues in a minority of breast carcinomas, as well as in normal and hyperplastic epithelium. Although the role of mucins in malignant transformation and the progression of breast cancer is not well understood, in some cases, there is probably an upregulation of several genes that encode distinct mucin proteins.     

Determination of Blomia tropicalis-specific IgE and IgG subclasses in atopic dermatitis patients

BACKGROUND: To verify the importance of Blomia tropicalis in atopic dermatitis (AD), we determined the cutaneous reactivity and the serum level of B. tropicalis-specific IgE and IgG subclasses in AD patients. METHODS: B. tropicalis-specific IgE and IgG subclasses were determined in AD patients and compared with bronchial asthma (BA) patients and a control group (CG) of nonatopic subjects. Specific IgE was obtained by skin prick test and RAST. B. tropicalis-specific IgG subclasses were determined by ELISA. The data were statistically analyzed by chi-square test (Mantel-Haenszel) and odds ratio (OR). RESULTS: We detected positive skin prick tests in 61.76% of AD and 83.33% of BA patients, and in 12.5% of the CG. RAST was positive in 44.12% of AD and in 61.90% of BA patients, but not in the CG. B. tropicalis-specific IgG1 and IgG2 subclasses showed no significant differences between the three groups. IgG3 subclass positivity was statistically significant in AD patients (41.17%) when compared to BA patients (14.29%) and the CG (16.67%). The determination of B. tropicalis-specific IgG4 was positive in 32.35% of AD patients, 21.43% of BA patients, and 8.33% of the CG. CONCLUSIONS: These results confirm that the storage mite B. tropicalis is an important allergen in AD. It is possible that IgG3 activates the complement in AD patients, releasing vasoactive amines that further amplify the allergic reaction. The positive results of the B. tropicalis-specific IgG4 found in AD and BA were probably due to chronic exposure to this storage mite in the home environment.     

Natural polyreactive secretory immunoglobulin A autoantibodies as a possible barrier to infection in humans.

Secretory immunoglobulin A (S-IgA) was investigated in human secretions for the presence of natural antibodies (Abs) acting as the first "immune barrier" to infection before induction or boosting of specific responses. These molecules could be the secretory counterpart of the natural Abs in serum that were previously shown by our laboratory to be polyreactive to autoantigens. Significant levels of S-IgA Abs to human actin, myosin, tubulin, and spectrin were detected in 10 saliva and 8 colostrum samples from normal subjects. Computer-assisted analysis of immunoblots of extracts from human muscles showed these Abs to react with a large number of autoantigens. Their polyreactivity was confirmed by cross-inhibition and by immunoblotting studies of affinity-purified natural Abs, assayed against a large variety of surface or secreted antigens from Streptococcus pyogenes. The thiocyanate elution method showed that functional affinities of some natural Abs can be of the same order of magnitude as those of tetanus vaccine antitoxins. Moreover, nonimmune binding of these natural Abs to the gut protein Fv (Fv-fragment binding protein) can enhance their effector functions. This demonstrates that human secretions contain polyreactive auto-Abs which can also react with pathogens. These secretory Abs of "skeleton key" specificities are possibly produced by a primordial B-1-cell-associated immune system and can be involved in a plurispecific mucosal protection against pathogens, irrespective of the conventional immune response.     

Molecular characterization of human immunodeficiency virus (HIV)-1 and -2 in individuals from guinea-bissau with single or dual infections: predominance of a distinct HIV-1 subtype A/G recombinant in West Africa.

Guinea-Bissau in West Africa has the highest prevalence of human immunodeficiency virus (HIV)-2 infection in the world, but recently the HIV-1 prevalence increased rapidly with the subsequent appearance of HIV-1 and HIV-2 dual infections. Information about the genetic subtypes of HIV in the region is limited. Therefore, we characterized the env V3 region of HIV-1 and HIV-2 variants through direct DNA sequencing of peripheral blood mononuclear cell samples from 18 individuals with HIV-1 only and 9 individuals with dual infection. Phylogenetic analyses of these new sequences and database sequences from other West African countries showed that all HIV-1 and HIV-2 sequences from singly as well as dually infected individuals, except one, clustered among HIV-1 subtype A and HIV-2 subtype A, respectively. Importantly, a majority of the HIV-1 sequences from Guinea-Bissau and neighbouring countries were closely related with the isolates IbNG, DJ263, and DJ264, which share a common subtype A/G recombination pattern. Analysis of pol gene sequences from selected HIV-1 variants showed that "IbNG-like" viruses in Guinea-Bissau are also recombinant, indicating that the HIV-1 epidemic in Guinea-Bissau and neighbouring countries is dominated by an epidemic spread of a distinct subtype A/G recombinant, which is strikingly similar to the epidemic spread of a subtype A/E recombinant in Southeast Asia. Furthermore, the HIV-1 and HIV-2 variants carried by individuals with dual infection were intermixed with variants from singly infected individuals, indicating that variants involved in dual and single infections have common epidemiological histories.     

Monitoring gp43 antigenemia in Paracoccidioidomycosis patients during therapy

Paracoccidioidomycosis (PCM) is a systemic fungal disease that is particularly important among individuals living and working in rural areas of endemicity in Latin America. Detection of anti-Paracoccidioides brasiliensis antibodies is of limited value due to false-negative results. Detection of P. brasiliensis-gp43 circulating antigen is a practical approach for a specific diagnosis of the disease. In a previous study we described an inhibition enzyme-linked immunosorbent assay able to detect the 43-kDa P. brasiliensis antigen in sera of 100% of patients with the acute form of PCM and in 95.31 and 100% of patients with the chronic multifocal and unifocal forms of PCM. To investigate its potential application for the follow-up of PCM patients during treatment, antigen levels were monitored at regular intervals for up 8 to 12 months in serum samples from 23 patients. The results showed that treatment with itraconazole resulted in decreasing levels of circulating gp43 that were correlated with the reduction of anti-gp43 antibodies. It was also observed that by the end of 12 months of treatment gp43 levels were <5 microg/ml in all patients.     

Recombinant cysteine proteinase from Leishmania (Leishmania) chagasi implicated in human and dog T-cell responses

High in vitro lymphoproliferative responses were induced in humans and dogs by a recombinant Leishmania (Leishmania) chagasi cysteine proteinase, with secretion of IFN-gamma in asymptomatic subjects or of IFN-gamma, interleukin 4 (IL-4), and IL-10 in oligosymptomatic subjects. In contrast, responses of symptomatic patients and dogs were lower, with production of IL-4 and IL-10.     

Molecular characterization of Vibrio cholerae O1 strains isolated during cholera outbreaks in Guinea-Bissau.

In the present study, 19 strains of Vibrio cholerae O1 biotype El Tor isolated during outbreaks of cholera in Guinea-Bissau in 1987, 1994, and 1995 were characterized to investigate a possible epidemiological relationship among the isolates. On the basis of ribotyping with the restriction enzyme BglI, 5 strains isolated in 1987 showed two closely related ribotypes, while 14 strains isolated in 1994 and 1995 showed the same ribotype that was distinct from the ribotypes of strains isolated in 1987. Southern blot hybridization of BglI-digested genomic DNA with a cholera toxin probe demonstrated that the strains isolated in 1987 showed an identical cholera toxin genotype, whereas O1 strains isolated in 1994 and 1995 showed the same genotype that was distinct from the genotype of strains isolated in 1987. These results were supported by the results of antibiotic susceptibility testing, in which strains isolated in 1987 showed resistance to polymyxin B only, while each of the strains from 1994 and 1995 showed resistance to polymyxin B, trimethoprim-sulfamethoxazole, and the vibriostatic agent O/129. Although our results are based on a limited number of V. cholerae O1 strains, they suggest that the epidemic in Guinea-Bissau in 1994 and 1995 was due to the introduction of a new strain to the country.