Is there any correlation between HLA-DR expression in laryngeal mucosa and interleukin gene variation in sudden infant death syndrome?

Aim: The mucosal immune system and cytokines are activated in a large proportion of cases of sudden infant death syndrome (SIDS). Our aim was to search for a possible association between cytokine polymorphisms and immune stimulation of the laryngeal mucosal in SIDS.

Methods: HLA-DR expression in laryngeal mucosal glands and surface epithelium in 97 SIDS victims was evaluated applying a semi-quantitative scoring system. The findings were related to cytokine gene polymorphisms as well as to the level of various cytokines in the cerebrospinal fluid (CSF). A risk score was established: a score of 0 prepresenting negative HLA-DR, supine position and no fever prior to death.

Results: The IL-6 -176CG/CC genotype was found in 92.3% of the SIDS cases with positive score for all risk factors (p = 0.01). Infants with high HLA-DR score had high levels of IL-6 in the cerebrospinal fluid (>30 μg/L) (p = 0.005). Furthermore, the IL-8 SNPs -781 CT/TT genotypes and -251 AA/AT genotypes were observed in 93% of the SIDS cases with one or more of the risk factors present compared with SIDS cases no risk factors reported (p = 0.003 and p = 0.016, respectively).

Conclusion: This study adds further evidence to the hypothesis that there are genetically associated disturbances of immunological homoeostasis in SIDS.