Defective FOXP3 expression in patients with acute Kawasaki disease and restoration by intravenous immunoglobulin therapy

Objective. The aims of this study were: 1) to investigate forkhead box P3 (FOXP3) expression in patients with Kawasaki disease (KD), exploring possible differences during the acute phase and after defervescence; 2) to evaluate a possible association of the FOXP3 single nucleotide polymorphism (SNP) 543 (SNP ID: rs2232367) with KD. Methods. FOXP3 expression was evaluated on 8 children with KD and 15 healthy children by flow cytometry and Real-Time polymerase chain reaction (RT-PCR). FOXP3 SNP 543 was genotyped by denaturing high-performance liquid chromatography (DHPLC) and sequencing on DNA samples from 58 additional children with KD and 114 healthy donors. Results. The frequencies of CD4+CD25 +FOXP3+ regulatory T cells were significantly (p=0.0002) lower during the acute phase of KD than in sex-and age-matched healthy donors (median % ± SD: 4.8±1.3 vs. 7.7±1.7) and a similar tendency was revealed for FOXP3 mRNA transcripts (pT; for a total of 1 allele out of 88), with no difference between KD patients and controls (0.0%, 0/203 alleles). Conclusion. Our data reinforce the notion of an impaired immunoregulation in KD, suggesting also a role of IVIG treatment in modifying the Treg com-partment. FOXP3 SNP 543 does not seem to be involved in susceptibility to KD in Italian children.