Eighty-two patients with definite HIT and two control groups were studied. The first control group (Abneg) consisted of 85 patients without Abs to PF4/heparin after cardiopulmonary bypass (CPB). The second control group (Abpos) consisted of 84 patients who had developed significant levels of PF4-specific antibodies after CPB, but without HIT.
Allele frequencies of the 3 SNPs were similar in HIT patients and controls. Fourteen alleles in IL10G (G16 to G29) and 3 alleles in IL10R (R13 to R15) were defined. The short G20 allele of IL10G was more frequent in Abneg patients (8.2%) than in Abpos (2.9%) and HIT patients (3%). It thereby appeared to protect against developing Abs to PF4/heparin (OR 0.29; 95%CI [0.12-0.70], p = 0.006). Combined haplotypes cH1/cH8 comprising the short G20 + R13 alleles were less frequent in HIT (OR 0.33; 95%CI [0.11-0.97], p = 0.036), and levels of Abs to PF4 in Abpos patients were lower in cH1/cH8 subjects (p = 0.019).
These results suggest that IL10 promoter microsatellite polymorphisms might influence the immune response against PF4/heparin and the risk of HIT.