Immunological risk factors for infection after immunosuppressive and biologic therapies.

Immunosuppressive and biologic therapies are costly and can involve a considerable risk of infection. Noninvasive diagnostic tools for early prediction of infection before and after administration of these therapies are of major interest. Serial longitudinal immune monitoring would provide data on immunocompetence and complement clinical follow-up protocols. Biomarkers of immune response may be useful to identify patients at risk of developing infection and who could be candidates for immunosuppressant dose reduction. This article focuses on the potential use of biomarkers of immune response to predict development of infection after immunosuppressive and biologic therapies in selected settings of autoimmune disease (rituximab for treatment of rheumatoid arthritis) and solid organ transplantation.

Lack of evidence of a role of XBP1 and PRDM1 polymorphisms in Spanish patients with immunoglobulin A deficiency.

The etiology of selective immunoglobulin A deficiency (IgAD) is not yet unraveled, but genetics seem to play an important role. Defects in processes during B-cell differentiation into plasma cells could exist in these patients, turning the genes controlling these processes into interesting candidate genes for IgAD predisposition, as PRDM1 (encoding Blimp-1) and XBP1. We studied the involvement of several polymorphisms located in PRDM1 and XBP1 on IgAD susceptibility. We performed a case-control study with 331 Spanish IgAD patients and 717 healthy controls, by analyzing five single nucleotide polymorphisms (SNPs) in these genes. Genetic frequencies of the studied SNPs did not significantly differ between patients and controls, even after stratifying by the known human leukocyte antigen risk factors or clinical phenotypes. Interaction between PRDM1 and XBP1 to confer disease predisposition was not detected either. In conclusion, the polymorphisms studied in the PRDM1 and XBP1 genes do not seem to be involved in IgAD predisposition in the Spanish population.

Interleukin-6 gene variation in Spanish patients with immunoglobulin-A deficiency.

Selective immunoglobulin-A deficiency (IgAD) is the most common immunodeficiency in Caucasian populations. Genetic factors are important in its etiology; however human leukocyte antigen (HLA) genes, which explain 40% of the genetic risk for IgAD, are the only susceptibility factors commonly agreed upon at this time. Because interleukin-6 (IL-6) plays an important role in B-lymphocyte differentiation from plasma cells, we aimed to address the IL-6 genetic influence on IgAD susceptibility. We performed a case-control study that included 305 Caucasian Spanish IgAD patients and 529 ethnically matched healthy control subjects, as well as a familial study with 128 IgAD trios. We genotyped the functional promoter polymorphism -174G>C and nine additional single nucleotide polymorphisms. For the case-control analyses the chi(2) test or Fisher's exact test were used, and for the family study the transmission disequilibrium test was used. We observed an increased frequency of the -174C allele in IgAD patients (p = 0.005, odds ratio [OR] = 1.51, 95% confidence interval [CI] = 1.12-2.04) and a protective effect of the rs2069849_C allele (p = 0.007, odds ratio = 0.29, 95% CI = 0.09-0.76). In conclusion, we described for the first time an association between IL6 polymorphisms and IgAD. Although it is not clear which genetic variants are causing susceptibility/protection, this intriguing finding is remarkable because of the role of IL-6 in antibody production.