However, it was also reported that total IgE levels were significantly elevated in children with severe malaria carrying the ?590T allele [27]. Among men with homozygous A/A IFN- genotype, the heterozygous IL-13 genotype C/T was associated with resistance relative to the homozygous C/C or T/T genotypes (OR?=?22.5 [CI 3.5, 144.4]). No increases in odds of resistance were found Astragaloside IV in relation to the IL-13 genotype among those with a T allele in the IFN- gene or in relation to the IFN- genotype among those with a heterozygous IL-13 genotype. Calculation of the attributable proportion of resistance showed a significant synergistic conversation between IL-13 ?1055 C/T and IL-4 ?590 C/T. Conclusions The recognized polymorphisms do not Astragaloside IV by themselves confer resistance or susceptibility, but we propose that these genotypes allow the resistant phenotype to be developed and expressed upon suitable immune exposure. Based on the literature, these polymorphisms contribute to the regulation of their respective cytokines, likely leading to downstream differences in the production and interrelationships of crucial defense mechanisms. Author Summary Approximately 200 million people have schistosomiasis in parts of Africa, South America, the Middle East, the Caribbean and Asia. Several studies of multiple treatments and reinfections show that some people develop resistance to reinfection. Of all the immunologic findings associated with such studies, the most consistent observation is usually that resistance (usually defined as lower levels of contamination upon reinfection) correlates with high IgE and low IgG4 antibodies against schistosome antigens. Our studies test whether single nucleotide polymorphisms residing in the gene or promoter regions of cytokines pivotal in controlling production of these antibody isotypes are different amongst those that develop resistance Astragaloside IV to reinfection as opposed to those that do not. Through genotyping of these polymorphisms in a cohort of occupationally uncovered car washers, we found that men with certain genotypic Astragaloside IV patterns of polymorphisms in IL-4, IFN-, and IL-13 were significantly more likely to be resistant to reinfection than those with different patterns. These data provide initial insights into the potential genetic foundation of propensities of people to develop resistance to reinfection by schistosomes, and offer Rabbit polyclonal to TIMP3 a basis for further molecular studies of how these polymorphisms might work at the transcriptional and gene product level in cells stimulated by schistosome antigens. Introduction There have been many studies of resistance to schistosome infections in humans following treatment and reinfection. Such studies involve paperwork of cases of schistosomiasis, their treatment and cure, and examinations at a later date to see if reinfections occurred [1],[2],[3],[4]. Of all the immunologic findings associated with these investigations, the most consistent observation is usually that resistance (usually defined as lower levels of contamination) correlates with high IgE and low IgG4 antibodies against schistosome antigens [5],[6],[7],[8],[9],[10],[11],[12],[13],[14],[15],[16],[17],[18]. Other studies have reported that production of IFN- and IL-5 to schistosome antigens are also correlated with resistance [19],[20],[21],[22]. A genetic region (SM1) has been identified that shows a strong positive correlation to the level of contamination in humans [23]. SM1 maps to chromosome 5 in the 5q31Cq33 region that contains several genes associated with immune responses [24],[25]. These genes code for proteins that are associated with the regulation of Th2-type responses such as IL-3, IL-4, IL-5, IL-9, and IL-13 and IgE. Polymorphisms in these cytokines that lead to an increase or decrease in cytokine levels could influence the antibody isotypes and cellular interactions that in turn may contribute to resistance or susceptibility of individuals to reinfection with schistosomiasis. There have been contradictory reports on the effect the IL-4 ?590 C/T (rs 2243250) polymorphism has on IgE levels in different settings. One group found that infants with a IL-4 ?590 C allele had a higher risk of elevated IgE in their cord blood [26]. However, it was also reported that total IgE levels were significantly Astragaloside IV elevated in children with severe malaria transporting the ?590T allele [27]. It is well known that IL-4 plays an important role in IgE class switching [28] and reports that this ?590 C/T polymorphism are associated with differing amounts of IgE made it a candidate for this study. Kouriba, et al. reported that IL-13 ?1055C (rs 1800925) and ?591A (rs 2069743) were associated with the upper 10% infection levels in individuals infected with (susceptibility) [29]. Van der Pouw Kraan et al. explained an NF-AT binding site at IL-13 -1055 that showed increased binding of nuclear proteins with the T allele [30]. Furthermore, it was reported that transcription of the IL-13 -1055T allele was enhanced in Th2 polarized CD4+ cells, but not in nonpolarized (i.e., Th0) CD4+ T cells [31]. Thus,.