ENHANCED REACTIVITY OF ALZ-50 ANTIBODY IN BRAINS OF SUDDEN-INFANT-DEATH-SYNDROME VICTIMS VERSUS BRAINS WITH LETHAL HYPOXIC ISCHEMIC INJURY - DIAGNOSTIC-SIGNIFICANCE AFTER APPLICATION OF THE IMMUNOMAX TECHNIQUEON ROUTINE PARAFFIN MATERIAL/

Alz-50 antibody is immunoreactive with brain tissue of subjects with A lzheimer's disease and can also be demonstrated by immunocytochemistry in neurons of vibratome-prepared brain tissue of victims of sudden in fant death syndrome (SIDS!. The application of a slightly modified Imm unoMax method enabled us to demonstrate Alz-50 immunoreactivity in par affin-embedded material. The Alz-50 epitope was detected in the hippoc ampus region and in nuclei of the medulla oblongata at the level of th e inferior olivary protuberance in three diagnostic groups: victims of SIDS (ii = 10), infants dying of subacute hypoxia/ischemia with subse quent (re-)perfusion (n = 9), and infants dying of acute ischemia with out (re-)perfusion (n = 7). Quantitative evaluation of the hippocampal cortex and the nucleus olivaris inferior disclosed a significantly (P < 0.05) higher percentage of Alz-50-reactive neurons in SIDS cases th an in the control groups (hippocampal cortex and nucleus olivaris; SID S victims: median = 100%; subacute hypoxia/ischemia: median = 33.6-81% ; acute ischemia: median = 89.2-99%). Semiquantitative analysis reveal ed an equally pronounced preponderance of Alz-50-reactive neurons in S IDS victims versus the control groups. This greater expression in SIDS victims may be due to an ongoing hypoxia/ischemia during agony, but t he present paucity of knowledge prohibits definitive elucidation. Neve rtheless, the method described here appears to offer the realistic pos sibility of distinguishing SIDS cases from cases of sudden death in in fants due to other causes, i.e., it offers for the first time a positi ve criterion for the diagnosis of SIDS.