Alcinda Campos Melo

Expansion of circulating Foxp3+CD25bright CD4+ T cells during specific venom immunotherapy

Background Venom immunotherapy (VIT) induces long‐lasting immune tolerance to hymenoptera venom antigens, but the underlying mechanisms are not yet clarified. Regulatory T cells are thought to play an important role in allergic diseases and tolerance induction during specific immunotherapy.

Primary B-Cell Deficiencies Reveal a Link between Human IL-17-Producing CD4 T-Cell Homeostasis and B-Cell Differentiation

IL-17 is a pro-inflammatory cytokine implicated in autoimmune and inflammatory conditions. The development/survival of IL-17-producing CD4 T cells (Th17) share critical cues with B-cell differentiation and the circulating follicular T helper subset was recently shown to be enriched in Th17 cells able to help B-cell differentiation. We investigated a putative link between Th17-cell homeostasis and B cells by studying the Th17-cell compartment in primary B-cell immunodeficiencies. Common Variable Immunodeficiency Disorders (CVID), defined by defects in B-cell differentiation into plasma and memory B cells, are frequently associated with autoimmune and inflammatory manifestations but we found no relationship between these and Th17-cell frequency. In fact, CVID patients showed a decrease in Th17-cell frequency in parallel with the expansion of activated non-differentiated B cells (CD21lowCD38low). Moreover, Congenital Agammaglobulinemia patients, lacking B cells due to impaired early B-cell development, had a severe reduction of circulating Th17 cells. Finally, we found a direct correlation in healthy individuals between circulating Th17-cell frequency and both switched-memory B cells and serum BAFF levels, a crucial cytokine for B-cell survival. Overall, our data support a relationship between Th17-cell homeostasis and B-cell maturation, with implications for the understanding of the pathogenesis of inflammatory/autoimmune diseases and the physiology of B-cell depleting therapies.

Monocyte activation is a feature of common variable immunodeficiency irrespective of plasma lipopolysaccharide levels

Common variable immunodeficiency disorders (CVID), the most frequent cause of symptomatic primary immunodeficiency, are defined by impaired antibody production. Notwithstanding, T cell activation and granulomatous manifestations represent the main causes of CVID morbidity even in patients receiving immunoglobulin (Ig) G replacement therapy. Additionally, gut pathology is a frequent feature of CVID. In this study, we investigated monocyte imbalances and their possible relationship with increased microbial translocation in CVID patients. Monocyte subsets were defined according to CD14 and CD16 expression levels and evaluated in terms of human leucocyte antigen D‐related (HLA‐DR), CD86 and programmed death‐1 molecule ligand 1 (PD‐L1) expression by flow cytometry, in parallel with the quantification of plasma lipopolysaccharide (LPS) and serum levels of soluble CD14 (sCD14), LPS‐binding protein (LBP) and anti‐LPS antibodies. CVID patients (n = 31) featured significantly increased levels of serum sCD14 and an expansion of CD14brightCD16+ monocytes in direct correlation with T cell and B cell activation, the latter illustrated by the frequency of the CD21lowCD38low subset. Such alterations were not observed in patients lacking B cells due to congenital agammaglobulinaemia (n = 4). Moreover, we found no significant increase in circulating LPS or LBP levels in CVID patients, together with a relative preservation of serum anti‐LPS antibodies, in agreement with their presence in commercial IgG preparations. In conclusion, CVID was associated with monocyte imbalances that correlated directly with T cell activation markers and with B cell imbalances, without an association with plasma LPS levels. The heightened monocyte activated state observed in CVID may represent an important target for complementary therapeutic strategies.

Reduced BAFF-R and increased TACI expression in common variable immunodeficiency.

PurposeB-cell survival and differentiation critically depend on the interaction of BAFF-R and TACI with their ligands, BAFF and APRIL. Mature B-cell defects lead to Common Variable Immunodeficiency (CVID), which is associated with elevated serum levels of BAFF and APRIL. Nevertheless, BAFF-R and TACI expression in CVID and their relationship with ligand availability remain poorly understood.Methods and ResultsWe found that BAFF-R expression was dramatically reduced on B cells of CVID patients, relative to controls. BAFF-R levels inversely correlated with serum BAFF concentration both in CVID and healthy subjects. We also found that recombinant BAFF stimulation reduced BAFF-R expression on B cells without decreasing transcript levels. On the other hand, CVID subjects had increased TACI expression on B cells in direct association with serum BAFF but not APRIL levels. Moreover, splenomegaly was associated with higher TACI expression, suggesting that perturbations of TACI function may underlie lymphoproliferation in CVID.ConclusionsOur results indicate that availability of BAFF determines BAFF-R and TACI expression on B cells, and that BAFF-R expression is controlled by BAFF binding. Identification of the factors governing BAFF-R and TACI is crucial to understanding CVID pathogenesis, and B-cell biology in general, as well as to explore their potential as therapeutic targets.

The Contribution of the Basophil Activation Test to the Diagnosis of Hypersensitivity Reactions to Oxaliplatin

Cytostatics, mainly oxaliplatin, are widely used to treat oncological diseases. There has been an increase in hypersensitivity reactions to these drugs, mostly IgE-mediated. Skin tests are the main diagnostic method used but they may induce irritant local reactions and contamination by health care professionals. The main goals of this work were to evaluate the contribution of the basophil activation test (BAT) as a diagnostic tool for hypersensitivity reactions to oxaliplatin, and to compare the expression of CD63 and CD203c molecules. BAT was performed with oxaliplatin in 6 oncological patients with previous documented hypersensitivity reactions to oxaliplatin and in 5 controls (4 oncological patients tolerant to oxaliplatin and 1 healthy control), assessing CD63 and CD203c expression on basophil population. We found higher values for the basophil activation percentage and mean stimulation index for CD203c expression with all oxaliplatin concentrations tested (most significant at 150 μg/mL: p = 0,0087; p = 0.0222) in the patients than in controls. The same did not occur, with statistical significance, for CD63 expression. When we compared the 2 activation markers in the patients, we observed a more enhanced expression of CD203c in both evaluations, with statistical significance at the 150-μg/mL concentration (p = 0,026; p = 0,0129). These data show a higher positivity of BAT with oxaliplatin in patients with previous hypersensitivity reactions, when compared to controls, suggesting that BAT may be a promising diagnostic method as an alternative to skin tests. CD203c appears to play a more prominent role than CD63, which is consistent with what is published in the literature.

Poster 1020: Efficacy and safety of sublingual specific immunotherapy with Pru p 3 in a portuguese population - clinical and immunological evaluation during 12 months

Background Peach allergy is prevalent, persistent and potentially severe. LTPs (Pru p 3) and profilins (Pru p 4) are the main allergens involved in this kind of allergy in patients(pts) of Mediterranean area. The hidden presence of LTPs in foodstuffs and in other food involved in LTP syndrome can trigger severe reactions, including anaphylaxis. Thus, this type of allergy can be considered an important target for specific immunotherapy(IT).