Serum autoantibodies directed against transglutaminase-2 have a low avidity compared with alloantibodies against gliadin in coeliac disease

Avidity of anti-phospholipid antibodies in relation to their levels

Introduction

The heterogeneity of anti-phospholipid antibodies can be manifested not only in different antigenic specificities, but also in their avidities. The aim of the study was to investigate the relationship between anti-cardiolipin antibody (aCL) IgG avidities and levels within the range of their titres, from very low to high ones.

Material and methods

We analyzed 78 serum samples from 60 patients by ELISA with chaotropic agents, using urea concentration of 6 and 8 mol/l and single diluted serum samples. The changes of aCL levels and avidities were explored during a long-term follow-up in 14 patients.

Results

The avidities of aCLs did not differ in the groups of patients classified according to aCL levels. The higher avidity antibodies predominated in our patients and the fluctuation of avidities in the longitudinal follow-up did not show significant differences. No relationship between aCL levels and their avidities was found.

Conclusions

aCL avidities seem to have no relationship with aCL levels and high-avidity aCLs; the potentially deleterious effects might be present also in patients with low and extremely low aCL levels. Avidity of aCLs belongs to stable characteristics with insignificant changes in time.

The Pros and Cons of Using Oat in a Gluten-Free Diet for Celiac Patients

A therapeutic gluten-free diet often has nutritional limitations. Nutritional qualities such as high protein content, the presence of biologically active and beneficial substances (fiber, beta-glucans, polyunsaturated fatty acids, essential amino acids, antioxidants, vitamins, and minerals), and tolerance by the majority of celiac patients make oat popular for use in gluten-free diet. The health risk of long-time consumption of oat by celiac patients is a matter of debate. The introduction of oat into the diet is only recommended for celiac patients in remission. Furthermore, not every variety of oat is also appropriate for a gluten-free diet. The risk of sensitization and an adverse immunologically mediated reaction is a real threat in some celiac patients. Several unsolved issues still exist which include the following: (1) determination of the susceptibility markers for the subgroup of celiac patients who are at risk because they do not tolerate dietary oat, (2) identification of suitable varieties of oat and estimating the safe dose of oat for the diet, and (3) optimization of methods for detecting the gliadin contamination in raw oat used in a gluten-free diet.

The anti-carbamylated protein antibody response is of overall low avidity despite extensive isotype switching

Objective

To better understand the contribution of autoantibodies in RA and the biology of their responses, we evaluated the avidity of the anti-carbamylated protein (anti-CarP) antibody response.

Methods

The avidity of anti-CarP antibody, ACPA and anti-tetanus toxoid IgG were determined using elution assays. Anti-CarP IgG avidity was measured in sera of 107 RA patients, 15 paired SF and serum samples and 8 serially sampled sera before and after disease onset.

Results

The avidity of anti-CarP IgG is low compared with the avidity of anti-tetanus toxoid IgG present in the same sera. Likewise, although less pronounced, anti-CarP also displayed a lower avidity as compared with the avidity of ACPA IgG. No difference in anti-CarP IgG avidity is observed between ACPA positive or ACPA negative patients. Anti-CarP IgG avidity is higher in anti-CarP IgM-negative compared with IgM-positive individuals. Furthermore, the anti-CarP avidity in serum is higher than in SF. Using samples of individuals that over time developed RA we observed no anti-CarP avidity maturation in the years before disease onset. In contrast to ACPA avidity, the anti-CarP avidity is not associated with severity of joint destruction.

Conclusion

The anti-CarP response is of overall low avidity, even lower than the ACPA IgG avidity, and does not show apparent avidity maturation before or around disease onset. Overall, isotype switch and avidity maturation seem to be uncoupled as isotype switch occurs without avidity maturation, pointing towards a commonality in the regulation of both autoantibody responses as opposed to the pathways governing recall responses.

Occurrence of serum antibodies against wheat alpha-amylase inhibitor 0.19 in celiac disease

The alcohol-soluble fraction of wheat gluten (gliadins) induces in genetically susceptible individuals immunologically mediated celiac disease (CLD). However, gliadins and related cereal proteins are not unique foodstuff targets of CLD patients´ immune system. Non-gluten wheat alpha-amylase inhibitor 0.19 (AAI 0.19) has been found to be capable of activating human monocyte-derived dendritic cells and inducing pro-inflammatory status in intestinal mucosa of patients with celiac disease (CLD). The possible contribution of this reactivity in incomplete remission of CLD patients on a gluten-free diet (GFD) is matter of contention. In an attempt to characterize the antigenicity of AAI 0.19 in patients with active CLD, patients on a GFD and healthy controls we developed ELISA employing wheat recombinant AAI 0.19. Using this test we revealed a significant (P<0.001) elevation of IgA anti-AAI 0.19 antibodies (Ab) in patients with active CLD (12 out of 30 patients were seropositive) but also in CLD patients on a GFD (15/46), in contrast to healthy controls (2/59). Anti-AAI 0.19 IgG Ab levels were increased (P<0.001) only in patients with active CLD (14/30) in contrast to the controls. Interestingly, the levels of anti-AAI 0.19 IgG Ab were decreased in CLD patients on a GFD (P<0.001, 1/46) compared to the controls (1/59). Notably, 20 out of 30 patients with active CLD were positive either for IgA or for IgG anti-AAI 0.19 Ab. Thus, the majority of CLD patients developed a robust IgA and IgG Ab response against AAI 0.19. These findings may contribute to the broadening of the knowledge about CLD pathogenesis.