Abstract â–¡ 110

Background. Allergic and anaphylactoid reactions caused by increased degranulation of mast cells have been proposed as possible pathophysiological mechanisms in SIDS. This mast cells hyper-releasibility, if exists, would be an endogenous defect of the mast cells and, therefore, genetically inherited. Hence, this defect could be found also in family members of SIDS cases.

Objective. The purpose of the study was to evaluate mast cells hyper-releasibility in two groups of subjects: a) family members of SIDS cases, b) infants who had experienced an apparent life threatening event (ALTE) and their family members.

Patients and Methods. 6 infants post ALTE and their 16 first degree relatives (group A, 6 families) and 46 first degree relatives of SIDS cases (group B, 11 families) were compared to 71 age matched controls (17 families). Mast cells hyper-releasibility was assessed, in each subject, by the skin reactions to intra-dermal injections of 0.2 cc of the each of the following substances (mast cell degranulators and histamine): Histamine 0.0001 mg/ml, Histamine 0.001 mg/ml, Codeine 0.5 mg/ml, Codeine 1 mg/ml, Compound 48/80 0.05 mg/ml, Compound 48/80 0.1 mg/ml and Phenol-Saline (the solvent, as control). The shapes of the wheal and the flare reactions were copied onto a paper using an adhesive tape. The size and the shape of the skin reactions were analysis by computerized planimetry.

Results. Except for the flare reaction to histamine, all skin reactions to each of the various substances among the subjects of the study groups were significantly larger than the reactions in the controls (p<0.05)). In infants under 1 year of age, a significant difference was observed only compound 40/80 (0.1 mg/ml and for codeine (both concentrations). 23 out of the 68 subjects in the study group showed skin reactions that were greater than the mean±2SD of the control group for at least one of the substances. These 23 subjects belonged to 11/17 families of the study group (65%): 3/6 in group A (50%), and 8/11 families in group B (73%). No significant differences was found in the skin reaction to each of the substances between the two study groups.

Conclusions. Allergic mechanisms may play a role in at least in some of the cases of SIDS and ALTE. Products of mast cells degranulation, such as Codeine and Compound 48/80 could be markers for some infants at increased risk for SIDS. Some ALTE cases share common mechanisms with SIDS.