Immunohistochemical classification of astrocytes in infants by glial fibrillary acidic protein staining and application to forensic practice.

This study was designed to assess whether development of the astrocytes in central nervous system (CNS) is delayed in victims of the sudden infant death syndrome (SIDS), and to try the classification of astrocytes by a morphological method. The glial fibrillary acidic protein (GFAP) is the major component of astrocytic fiber and is characteristic of astrocytes in the human CNS. An immunohistochemical study identificating this protein was carried out on infant brains to evaluate astrocytes. Morphologically 39 brains of infants aging under 12 months old, that including 10 asphyxia, 13 respiratory infections and 16 SIDS cases, were stained for GFAP by the peroxidase-anti-peroxidase (PAP) method. According to their staining pattern astrocytes were classified into 4 cell types: Type I cells were seen during the non-proliferating period, Type II cells during the low-proliferating period, Type III cells during the moderate-proliferating period and Type IV cells during the high-proliferating period. On the basis of this classification of astrocytes, it was observed that the first and most reactive pattern of physiological proliferation was in infant brains four months old after birth in the asphyxia cases. The staining grade of astrocytes was significantly less in white matter in the SIDS victims compared with age-matched of the respiratory infections and asphyxia. Therefore, we suggest that development of brain in the SIDS cases is delayed to controls and that the SIDS is associated with a developmental CNS disorder. Among 3 group cases the retarded staining pattern of the astrocytes in SIDS is interesting and might give a helpful approach to diagnosis of the cause of death for SIDS.