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1.
Braz. j. med. biol. res ; 52(7): e8292, 2019. tab, graf
Article in English | LILACS | ID: biblio-1011589

ABSTRACT

The thymus is a primary lymphoid organ responsible for the maturation of T cells as well as the immunological central tolerance. It is in the antenatal period and infancy that it plays its major role. In clinical practice, T cell receptor excision circles (TRECs) are considered a direct and reliable measure of the thymic function. TRECs are a by-product of DNA formation in gene rearrangement of T cell receptors. They are stable and they do not duplicate during mitosis, representing the recent emigrant T cells from the thymus. Despite their importance, TRECs have been neglected by physicians and there is a lack of data regarding thymic function during infancy of healthy children. In order to evaluate thymic function in the first years of life, we propose measuring TRECs as a valuable tool. One hundred and three blood samples from children and adolescents between 3 months and 20 years of age were analyzed. The mean TRECs count was 136.77±96.7 copies of TRECs/μL of DNA. The individuals between 0 and 5 years of age had significantly higher TRECs values than those between 10 and 20 years of age. No significant difference was observed in TRECs values among age groups below 5 years of age. An inverse correlation between TRECs and age was found (r=0.3 P=0.003). These data highlight and validate the evidence of decreased thymus function with age, even during infancy. Awareness should be raised with this important albeit ignored organ.


Subject(s)
Humans , Infant , Child, Preschool , Child , Adolescent , Young Adult , Thymus Gland/physiology , Receptors, Antigen, T-Cell/physiology , Reference Values , Thymus Gland/cytology , Biomarkers/blood , Gene Rearrangement, T-Lymphocyte , Reproducibility of Results
2.
Braz. j. med. biol. res ; 43(12): 1215-1224, Dec. 2010. ilus, tab
Article in English | LILACS | ID: lil-568996

ABSTRACT

Rubinstein-Taybi syndrome (RTS) is a rare developmental disorder characterized by craniofacial dysmorphisms, broad thumbs and toes, mental and growth deficiency, and recurrent respiratory infections. RTS has been associated with CREBBP gene mutations, but EP300 gene mutations have recently been reported in 6 individuals. In the present study, the humoral immune response in 16 RTS patients with recurrent respiratory infections of possible bacterial etiology was evaluated. No significant differences between patients and 16 healthy controls were detected to explain the high susceptibility to respiratory infections: normal or elevated serum immunoglobulin levels, normal salivary IgA levels, and a good antibody response to both polysaccharide and protein antigens were observed. However, most patients presented high serum IgM levels, a high number of total B cell and B subsets, and also high percentiles of apoptosis, suggesting that they could present B dysregulation. The CREBBP/p300 family gene is extremely important for B-cell regulation, and RTS may represent an interesting human model for studying the molecular mechanisms involved in B-cell development.


Subject(s)
Adolescent , Child , Child, Preschool , Female , Humans , Male , Young Adult , Antibodies, Monoclonal/analysis , B-Lymphocytes/immunology , Immunity, Humoral/immunology , Immunoglobulins/analysis , Respiratory Tract Infections/immunology , Rubinstein-Taybi Syndrome/immunology , Antibodies, Monoclonal/immunology , Case-Control Studies , CREB-Binding Protein/genetics , Immunity, Humoral/genetics , Immunoglobulins/immunology , Recurrence
3.
Braz. j. med. biol. res ; 39(12): 1587-1592, Dec. 2006. ilus, tab
Article in English | LILACS | ID: lil-439690

ABSTRACT

The majority of children with Down syndrome (DS) tend to have frequent bacterial infections including recurrent respiratory infections. Our objective was to evaluate the production of antibodies to pneumococcal polysaccharide antigens after active immunization in DS subjects. IgG antibodies to pneumococcal serotypes (1, 3, 6B, 9V, and 14) were measured before and 6 weeks after immunization with a 23-valent pneumococcal vaccine (Pneumo23®, Pasteur-Merrieux) in 6- to 13-year-old DS children (N = 17) and in aged-matched normal controls (N = 30). An adequate response was defined as a 4-fold increase over baseline or a post-immunization level of specific pneumococcal serotype antibody > or = 1.3 æg/mL. After immunization, all DS children had an increase in post-immunization levels against all serotypes analyzed. A 4-fold or more increase was observed in all DS children concerning serotypes 1 and 14, in 90 percent of subjects for serotypes 3 and 9V, and in 65 percent for serotype 6B. Regarding this increase, 8 of the 17 DS children had an adequate response to all serotypes analyzed, 8/17 patients to 4 serotypes and 1/17 to 3 serotypes. However, when we compared post-immunization levels between DS children and controls, we observed lower levels in the former group (P < 0.05) for all serotypes except serotype 3. We conclude that pneumococcal polysaccharide immunization could be beneficial for these DS children.


Subject(s)
Humans , Male , Female , Child , Adolescent , Antibodies, Bacterial/immunology , Down Syndrome/immunology , Immunoglobulin G/immunology , Pneumococcal Infections/prevention & control , Pneumococcal Vaccines/immunology , Antibodies, Bacterial/blood , Case-Control Studies , Enzyme-Linked Immunosorbent Assay , Immunoglobulin G/blood
4.
Braz. j. med. biol. res ; 37(5): 625-634, May 2004. ilus, tab, graf
Article in English | LILACS | ID: lil-357541

ABSTRACT

Chronic granulomatous disease (CGD) is an inherited disorder of the innate immune system characterized by a defective oxidative burst of phagocytes and subsequent impairment of their microbicidal activity. Mutations in one of the NADPH-oxidase components affect gene expression or function of this system, leading to the phenotype of CGD. Defects in gp91-phox lead to X-linked CGD, responsible for approximately 70 percent of CGD cases. Investigation of the highly heterogeneous genotype of CGD patients includes mutation analysis, Northern blot or Western blot assays according to the particular case. The aim of the present study was to use reverse transcription (RT)-PCR for the analysis of molecular defects responsible for X-linked CGD in eight Brazilian patients and to assess its potential for broader application to molecular screening in CGD. Total RNA was prepared from Epstein B virus-transformed B-lymphocytes and reverse transcribed using random hexamers. The resulting cDNA was PCR-amplified by specific and overlapping pairs of primers designed to amplify three regions of the gp91-phox gene: exons 1-5, 3-9, and 7-13. This strategy detected defective gp91-phox expression in seven patients. The RT-PCR results matched clinical history, biochemical data (nitroblue tetrazolium or superoxide release assay) and available mutation analysis in four cases. In three additional cases, RT-PCR results matched clinical history and biochemical data. In another case, RT-PCR was normal despite a clinical history compatible with CGD and defective respiratory burst. We conclude that this new application of RT-PCR analysis - a simple, economical and rapid method - was appropriate for screening molecular defects in 7 of 8 X-linked CGD patients.


Subject(s)
Humans , Male , Child, Preschool , Child , Chromosomes, Human, X , Cytochrome b Group , Granulomatous Disease, Chronic , Reverse Transcriptase Polymerase Chain Reaction , DNA Mutational Analysis , Genetic Linkage , Genetic Markers , Point Mutation
5.
Braz. j. med. biol. res ; 29(2): 201-4, Feb. 1996. graf
Article in English | LILACS | ID: lil-161670

ABSTRACT

In order to study placental transfer of IgG subclasses, paired blood samples were collected from mothers and umbilical cord of preterm (N = 69) and full-term (N = 68) newborns. The full-term group was further divided into 3 subgroups: appropriate for gestational age (AGA, N = 43), large for gestational age (LGA, N = 13) and small for gestational age (SGA, N = 12), according to birth weight. IgG subclasses (IgG1, IgG2, IgG3 and IgG4) were measured by the single radial immunodiffusion technique using monoclonal antibodies. IgG1 and IgG3 newborn subclass concentrations (10.17 and 0.57 g/l, respectively) increased with increasing gestational age and reached maternal levels (IgG1 = 8.86; IgG3 = 0.67 g/l) during the 37th week of pregnancy. Low levels of these subclasses were found in premature newborns. IgG2 from newborns were always lower than maternal levels (P<0.05). LGA and SGA newborns had equivalent levels of IgG1 and IgG2 compared with AGA. SGA newborns had higher levels of IgG3 and lower levels of IgG4 than LGA and AGA newborns.


Subject(s)
Humans , Female , Pregnancy , Infant, Newborn , Immunization, Passive , Immunoglobulin G/blood , Infant, Premature/blood , Placenta/physiology , Infant, Newborn/blood , Immunoglobulin G/classification , Placenta/immunology , Receptors, Fc
6.
Braz. j. med. biol. res ; 29(2): 239-44, Feb. 1996. graf
Article in English | LILACS | ID: lil-161676

ABSTRACT

We have investigated different experimental schedules to achieve adherence of Neisseria meningitidis group B to cultured and buccal epithelial cells (BEC) and the effect of antibodies and receptor analogues on bacterial adherence. No adherence of meningococcus was observed when HeLa, HEp-2 or KB cells were used, but high rates of adherence to BEC occurred. The effect of antibodies on bacterial adherence was studied in assays carried out in the presence of saliva and serum collected from convalescing children with meningococcal meningitis and children vaccinated with VAMENGOC B-C. Both saliva and serum from the convalescent patients inhibited the adherence of meningococci, but saliva and serum from vaccinated children did not, corroborating our previous data of a poor antibody response induced by this vaccine. Human colostrum did not affect meningococcal adherence despite the presence of antibodies to N. meningitidis detected by ELISA. Inhibition of adherence by sera from an immunized horse, rabbits and mice, as well as by cell receptor analogues (outer-membrane complex and purified polysaccharide C), was observed. Our results show that up to now BEC continue to be the best cells to study meningococcal adherence and the effect of adherence inhibitors.


Subject(s)
Humans , Adhesins, Bacterial/immunology , Antibodies, Bacterial/pharmacology , In Vitro Techniques , Neisseria meningitidis/immunology , Bacterial Vaccines/administration & dosage , Bacterial Vaccines/immunology , Cell Culture Techniques , Nasopharynx/microbiology , Neisseria meningitidis/physiology
7.
Braz. j. med. biol. res ; 25(4): 369-73, 1992. ilus
Article in English | LILACS | ID: lil-109041

ABSTRACT

There is some controversy concerning the effect of intravenous long-chain triglyceride (LCT) emulsions on the phagocytic system and little is known about the effect of medium-chain triglyceride (MCT) containing emulsions. We evaluated the chemotaxis and random migration of human neutrophils from 18 healthy adult after preincubation with the following fat emulsions: LCT, MCT and a mixture of 50% MCT and 50% LCT (MCT/LCT). Leukocyte-rich plasma (4 x 10 6 cells/ml) was diluted 4:1 (v/v) with commercial fat emulsions (LTC, MCT, or MCT?LCT, 1:1) or saline and tumbled at 20 cycles?min for 30 min at 37 grade C. The final composition or the emulsion was 20 mg/ml fat, 0.24% egg yolk lecithin, and 0.5% glycerol and the dispersion was made isotonic by adding NaCl. In a second set of experiments, the LCT and MCT concentrations were adjusted to be equimolar. Leukocyte viability was * 95% after exposure to the treatment with fat emulsions. For emulsions with the same weight of each fat, random migration and chemotaxis of neutrophils were unaffected by the LCT emulsion but there was a significant decrease in both chemotaxis and random migration in MCT- (79 and 74%) or MCT/LCT-treated (60 and 56%) neutrophils. Similar results were obtained when LCT and MCT were equimolar. These results demonstrate an inhibitory effect of MCT on two human neutrophil functions which may be dose dependent


Subject(s)
Humans , Chemotaxis, Leukocyte , Fat Emulsions, Intravenous , Neutrophils , Triglycerides
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