Effect of Different Sensitization Events on HLA Alloimmunization in Kidney Transplantation Candidates.

BACKGROUND: HLA alloimmunization is caused by sensitization events (SEs), such as transfusion, pregnancy, or previous organ transplantation, and the effects of particular SEs have not been thoroughly studied. Our aim was to evaluate how each SE affected HLA alloimmunization by considering Luminex assays. METHODS: Sera from 722 kidney transplantation candidates were screened per protocol by means of Luminex assays to determine the presence of anti-HLA class I/II antibodies; positive sera underwent single-antigen assay to determine the presence of specific antibodies against HLA A, B, C, DR, DQ, DP loci (positivity if median fluorescence intensity values were >1,000). The effect of each SE was analyzed considering only patients exposed to 1 kind of sensitization. RESULTS: In the 453 candidates with ≥1 SE, anti-HLA class I positivity rates were significantly higher in patients with previous transfusion (18.9%; P = .014), pregnancy (38.3%; P < .001) or transplant (75%; P < .001) compared with those with no SE (similar results for class II). The strength (median fluorescence intensity) of specific antibodies was significantly higher in patients with previous transplantation than in those with previous transfusion for HLA-A (8,017 vs 2,302; P = .02), HLA-B (7,765 vs 2,901; P = .018), and HLA-DR (9,835 vs 2,060; P = .003). Other anti-HLA antibody strengths were similar between patients with previous pregnancy or transplantation. CONCLUSIONS: Presence of any SE analyzed was associated with a higher prevalence of anti-HLA antibodies for class I ± II compared with nonsensitized patients. Transplantation had the strongest immunization effect on both classes, followed by pregnancy and then transfusion.

Genotipificación de aislados clínicos de Helicobacter pylori en base a genes asociados a virulencia cagA, vacA y babA2: Primer aislamiento de una cepa babA2 positiva en pacientes chilenos / Genotypying of clinical isolates of Helicobacter pylori by cagA, vacA and babA2 virulence associated genes: First detection of a babA2 positive strain in Chilean patients

Background: Helicobacter pylori-associated gastroduodenal diseases depends on host characteristics, environmental conditions and bacterial virulence factors, such as cagA, vacA y babA2 gene products. Moreover, peptic ulcer disease has been related with cagA+, vacAs1m1 strains, while metaplasia and gastric cancer has been associated to cagA+, vacAs1 and babA2+ H pylori strains. Gene babA2 has not yet been described in clinical isolates from Chilean patients. Aim: To investigate the presence of cagA, vacA (s and m) and babA2 genes in clinical isolates of H pylori from Chilean patients. Material and Methods: Sixty six isolates from 41 patients were genotyped by PCR, using primers for s1a, s1b, s2, m1, m2, cagA and babA2 genes as previously described. Results: cagA gene was detected in 16 isolates (24.2 percent) while vacAs1a, vacAs1b, vacAs2, vacAm1 and vacAm2 were detected in 28 (42.4 percent), 14 (21.2 percent), 17 (25.8 percent), 21 (31.8 percent) and 29 isolates (43.9 percent), respectively. One isolate (1.5 percent) was babA2 positive, being the first isolate with this genotype described in Chile. Besides the babA2+ genotype this clinical isolate also presented cagA+ and vacAs1a which has been related with metaplasia or gastric cancer. Five isolates showed an ulcerogenic profile cagA+, vacAs1m1. Conclusions: The results presented indicate the prevalence of vacAs1m1 genotype among the clinical isolates analyzed, and a low frequency of babA2 genotype.