Immunohistochemical characterisation of the costo-chondral junction in sudden infant death syndrome (SIDS)

Abstract

A number of studies have concluded that infants who die of SIDS have evidence of significant growth retardation. Although there appears to be considerable overlap with control infants, reduced weight gain, poor neurological development and specific abnormalities of the bone growth plate have all been reported. This raises the possibility that SIDS infants may have been physiologically compromised for some time prior to death. Alteration of growth plate morphology may, however, be influenced by primary abnormalities of proteoglycan composition, given that growth plate organisation depends on the intimate interaction of chondrocytes with extracellular matrix. The following study was undertaken to characterise the distribution of major growth plate proteoglycans in a group of SIDS infants compared to control infants. Sections of rib and adjacent costal cartilage were taken at autopsy from 9 SIDS infants and 8 age- matched controls (4 asphyxial deaths, 2 traumatic deaths, 1 poisoning and 1 drowning). Following decalcification and routine processing, immunohistochemical staining was performed for chondroitin (ch)-4-SO 4 , ch-6-SO 4 , keratan SO 4 and over- sulphated ch-SO 4 with antibodies 2-B-6, 3-B-3, 5-D-4 and 7-D-4 using standard methods. The tested proteoglycans showed either a uniform or zonal distribution in the growth plate in SIDS infants, with an identical pattern of distribution in controls. This preliminary finding suggests that the abnormal growth plate morphology reported in a percentage of infants dying of SIDS may well be a secondary phenomenon , not related to primary skeletal dysfunction. In summary, the distribution of proteoglycans within the extracellular matrix of the costochondral junction in SIDS infants in this study appeared normal.