Peripheral blood monocyte and T cell subsets in children with specific polysaccharide antibody deficiency (SPAD)

Specific polysaccharide antibody deficiency (SPAD) is a well reported immunodeficiency characterized by a failure to produce antibodies against polyvalent polysaccharide antigens, expressed by encapsulated microorganisms. The clinical presentation of these patients involves recurrent bacterial infections, being the most frequent agent Streptococcus (S.) pneumoniae. In SPAD patients few reports refer to cells other than B cells. Since the immune response to S. pneumoniae and other encapsulated bacteria was historically considered restricted to B cells, the antibody deficiency seemed enough to justify the repetitive infections in SPAD patients. Our purpose is to determine if the B cell defects reported in SPAD patients are accompanied by defects in other leukocyte subpopulations necessary for the development of a proper adaptive immune response against S. pneumoniae. We here report that age related changes observed in healthy children involving increased percentages of classical monocytes (CD14++ CD16- cells) and decreased intermediate monocytes (CD14++ CD16+ cells), are absent in SPAD patients. Alterations can also be observed in T cells, supporting that the immune deficiency in SPAD patients is more complex than what has been described up to now.

Follicular bronchiolitis as phenotype associated with CD25 deficiency

Regulatory T cells [Tregs ; CD4(+) CD25(+) forkhead box protein 3 (FoxP3(+) )] are subsets of T cells involved in the maintenance of peripheral self-tolerance by actively suppressing the activation and expansion of autoreactive T cells. Signalling through the interleukin-2 receptor (IL-2R) contributes to T cell tolerance by controlling three important aspects of regulatory T cell (Treg ) biology. CD25 is the α-chain of the IL-2R that, in concert with the β-chain and γ-chain, constitutes the complete IL-2R. CD25 contributes only to IL-2 binding affinity but not to the recruitment of signalling molecules. However, its importance in the development of a normal immune response is emphasized by the finding that a truncation mutant of CD25 results in an immunodeficiency in humans characterized by an increased susceptibility to viral, bacterial and fungal infections. In 1997, Sharfe et al. described an infant with severe bacterial, viral and fungal infections. Counts of autologous T lymphocytes were moderately low, T cells displayed a weak proliferative response to mitogens in vitro and the patient displayed no rejection of an allogeneic skin graft. However, unlike children with severe combined immunodeficiency (SCID), besides not having circulating T cells, the patient also developed peripheral lymphocytic proliferation and autoimmune primary biliary cirrhosis. We present the first female Argentine patient with mutation in CD25 associated with chronic and severe inflammatory lung disease (follicular bronchiolitis with lymphocyte hyperplasia), eczema and infections. She has no expression of CD25 on CD4(+) T cells and an extremely low amount of Tregs . The molecular study confirmed homozygous missense mutation in the alpha subunit of the IL-2 receptor (CD25αR) (c. 122 a > c; p. Y41S).

Guidelines for the use of human immunoglobulin therapy in patients with primary immunodeficiencies in Latin America

Antibodies are an essential component of the adaptative immune response and hold long-term memory of the immunological experiences throughout life. Antibody defects represent approximately half of the well-known primary immunodeficiencies requiring immunoglobulin replacement therapy. In this article, the authors review the current indications and therapeutic protocols in the Latin American environment. Immunoglobulin replacement therapy has been a safe procedure that induces dramatic positive changes in the clinical outcome of patients who carry antibody defects.

Immune response to Streptococcus pneumoniae in asthma patients: comparison between stable situation and exacerbation

In Argentina, more than 3 million people suffer from asthma, with numbers rising. When asthma patients acquire viral infections which, in turn, trigger the asthmatic response, they may develop subsequent bacterial infections, mainly by Streptococcus (S.) pneumoniae. This encapsulated Gram(+) bacterium has been considered historically a T cell-independent antigen. Nevertheless, several papers describe the role of T cells in the immune response to S. pneumoniae. We evaluated the response to S. pneumoniae and compared it to the response to Mycobacterium (M.) tuberculosis, a different type of bacterium that requires a T helper type 1 (Th1) response, in cells from atopic asthmatic children, to compare parameters for the same individual under exacerbation and in a stable situation whenever possible. We studied asthma patients and a control group of age-matched children, evaluating cell populations, activation markers and cytokine production by flow cytometry, and cytokine concentration in serum and cell culture supernatants by enzyme-linked immunosorbent assay (ELISA). No differences were observed in γδ T cells for the same patient in either situation, and a tendency to lower percentages of CD4(+) CD25(hi) T cells was observed under stability. A significantly lower production of tumour necrosis factor (TNF)-α and a significantly higher production of interleukin (IL)-5 was observed in asthma patients compared to healthy individuals, but no differences could be observed for IL-4, IL-13 or IL-10. A greater early activation response against M. tuberculosis, compared to S. pneumoniae, was observed in the asthmatic patients' cells. This may contribute to explaining why these patients frequently acquire infections caused by the latter bacterium and not the former.

The role of cytokines in atopic asthma

Atopic asthma results from airway inflammation triggered by an environmental allergen. Symptoms include wheezing, dyspnea and cough, airway narrowing and/or hyperresponsiveness to several inhaled stimuli. Inflammation develops in a two-phase fashion. The first phase after exposure to the allergen consists of degranulation and release of both histamine and other stored preformed inflammatory mediators as well as newly synthesized ones, including cytokines, all of which increase mucus secretion and smooth muscle contraction. The second phase occurs later and lasts longer; it is due to different molecules: several cytokines and chemokines, arachidonic acid derivatives, enzymes such as metalloproteinases and cell adhesion molecules. Cytokines are key players in the chronic inflammation in asthma patients, but details on their role and interactions still remain undetermined. Recent evidence suggests that allergic asthma is a multifaceted condition actively controlled by effector as well as regulatory T cells (Tregs). T helper (Th) 2 cells and Th17 cells increase airway inflammation, while Tregs are anti- inflammatory. Cytokines are involved in the development and activation of all T cell subpopulations. They are also involved directly or indirectly in most approaches to asthma treatment. Several cytokines have been tested as therapeutic targets and some of the currently used therapies like corticosteroids, beta agonists and allergen immunotherapy affect cytokine production. The increased knowledge on cytokine interplay and lymphocyte subsets should generate new therapeutic strategies in the near future.

Primary immunodeficiency diseases in Latin America: proceedings of the Second Latin American Society for Immunodeficiencies (LASID) Advisory Board

Early diagnosis and appropriate therapy are essential for the best prognosis and quality of life in patients with primary immunodeficiency diseases (PIDDs). Experts from several Latin American countries have been meeting on a regular basis as part of an ongoing effort to improve the diagnosis and treatment of PIDD in this region. Three programmes are in development that will expand education and training and improve access to testing facilities throughout Latin America. These programmes are: an educational outreach programme (The L-Project); an immunology fellowship programme; and the establishment of a laboratory network to expand access to testing facilities. This report provides the status of these programmes based on the most recent discussions and describes the next steps toward full implementation of these programmes.

Critical issues and needs in management of primary immunodeficiency diseases in Latin America

Experts from six Latin American countries met to discuss critical issues and needs in the diagnosis and management of primary immunodeficiency diseases (PIDD). The diagnosis of PIDD is generally made following referral to an immunology centre located in a major city, but many paediatricians and general practitioners are not sufficiently trained to suspect PIDD in the first place. Access to laboratory testing is generally limited, and only some screening tests are typically covered by government health programmes. Specialised diagnostic tests are generally not reimbursed. Access to treatment varies by country reflecting differences in healthcare systems and reimbursement policies. An online PIDD Registry Programme for Latin America has been available since 2009, which will provide information about PIDD epidemiology in the region. Additional collaboration across countries appears feasible in at least two areas: a laboratory network to facilitate the diagnosis of PIDD, and educational programmes to improve PIDD awareness. In total, these collaborations should make it possible to advance the diagnosis and management of PIDD in Latin America.

[Kawasaki disease. Immunological evaluation of 26 cases]

Kawasaki disease (KD) is an acute febrile vasculitis of childhood, characterized by multiple clinical and biochemical features of inflammation with special involvement of the heart. The activation of lymphocytes and monocytes/macrophages and their secreted soluble products, cytokines, play a central role in the pathogenesis of the disease. In this study we performed immunologic studies in 26 patients with KD. No constant pattern of serum levels of IgG, IgA, IgM, C3 and C4 fractions of complement measured by Nephelometry and neither autoantibodies, FAN and ANCA performed by indirect immunofluorescence were found in 22 patients in the acute stage. Variable percentages of CD3, CD4, CD8, CD20, CD56 and DR in peripheral mononuclear cells specifically stained and analysed by flow cytometry were seen among 25 patients in the acute stage. CD25 was elevated in 17/25 cases. Serum levels of TNF alpha performed by ELISA in 12 patients in acute stage were low. Intracellular cytokines such as TNF alpha, IL1 beta, IL2 and IFN gamma were measured in peripheral mononuclear cells of 15 patients in acute stage, in 5th and 30th days after gammaglobulin treatment, utilizing specific staining and analysis by flow cytometry showing no sole characteristic profile. In 2 patients there was an elevated percentage of TNF alpha and IL1 beta in monocytes during the convalescent stage; both had coronary sequelae. More research on this question is needed. In conclusion, immunologic studies showed an heterogeneous profile and no laboratory finding was registered in the acute stage that could be used as predictive factor of cardiovascular involvement.

Progressive multifocal leukoencephalopathy in a patient with hypogammaglobulinemia

We describe a child with congenital hypogammaglobulinemia that was diagnosed at 13 months of age. When he was 4 years old, gait disturbances began. The main neurological manifestations were progressive spastic tetraparesis and intellectual and speech deterioration. No infectious agent was identified. A magnetic resonance imaging scan of the central nervous system revealed periventricular demyelinating areas in the frontal, temporal, and parietal lobes with cortical atrophy. Stereotactic brain biopsy confirmed the diagnosis of progressive multifocal leukoencephalopathy caused by JC virus. He was treated with intravenous and intraventricular cytarabine and interferon-alpha, and there was clinical improvement. We emphasize the need for brain biopsy as soon as a neurological complication is suspected in patients with congenital hypogammaglobulinemia for whom cerebrospinal cultures or polymerase chain reaction analyses are negative.

[Phenotypic changes in the mononuclear cells of patients with primary immunodeficiencies]

The study of differentiation antigens of circulating mononuclear cells in 70 patients with primary immunodeficiency (PID) using monoclonal antibodies allowed us to define phenotypic profiles that are characteristic of the different described syndromes. In common variable immunodeficiency we found percentages of lymphocytes within normal ranges, and an altered CD4/CD8 ratio. In sex-linked agammaglobulinemia, absence of B lymphocytes with normal distribution of regulatory populations (CD4/CD8) were found. These results allow us to distinguish two clinically and infectologically similar conditions. In selective IgA deficiency, distribution of lymphocytic populations was normal. In immunodeficiency with hyper IgM, considered up to date as an abnormal maturation of B lymphocytes, we observed a deficiency in cellular immune response, and a phenotypic profile characterized by: decreased number of CD3 cells, inverted CD4/CD8 ratio, and increased CD38 population; this profile being similar to the one that we found in predominantly cellular immunodeficiency. In predominantly cell-mediated immunodeficiency and in those immunodeficiencies associated to other defects (such as: hyper IgE syndrome, Di George syndrome), the most important finding was a significative increase in CD38 population. Although it's not possible to consider on this basis that there is a defect at the thymic level of T-cells maturation, the high levels of circulating CD38 cells were a clear indication of altered cellular immune response in our series of patients. Patients with predominantly cell-mediated immunodeficiency showed the lowest levels of CD4 cells and the corresponding inversion of CD4/CD8 ratio. In Di George syndrome we found a markedly diminished CD8 population that differentiates this entity from the rest of the studied syndromes. In chronic mucocutaneous candidosis distribution of lymphocytic populations was normal, but a significative increase in the percentages of CD11b+ cells was observed. In patients with antibodies deficiency that received substitutive treatment with gammaglobulin we found no variations in lymphocytic populations distribution. In the group of patients with altered cellular immunity treated with thymic hormones, observed phenotypic changes (increase in T-cells population, trend to normalization in CD4/CD8 ratio, and decrease in CD38 population) were transient, and lasted only during the treatment period. We considered that describing these phenotypic profiles is a useful diagnosis tool when evaluating patients with PID, since these profiles are characteristic and very stable.