Age-related BAX and Ki-67 Expression in Regional Lymph Nodes of Infants who Died from Measles: A Retrospective Immunohistochemical Study

Abstract

Background: Measles can produce substantial lymphoid tissue injury and immunosuppression, but age-related patterns of apoptotic and proliferative activity in regional lymph nodes during fatal measles in infancy remain insufficiently characterised. Aims: To evaluate age-related changes in BAX and Ki-67 immunohistochemical expression in regional lymph nodes of infants who died from measles. Study Design: A retrospective morphological and immunohistochemical study of archived autopsy specimens. Methodology: Regional lymph node specimens from 83 infants were examined. The study groups were ≤1 month (n=18), 2–6 months (n=42), and 6–12 months (n=23); the ≤1-month group was further divided into early and late neonatal subgroups. Paraffin-embedded sections were evaluated histologically and by immunohistochemistry using the streptavidin–biotin peroxidase method with diaminobenzidine visualisation and haematoxylin counterstaining. BAX was assessed using the Immunoreactive Score, whereas Ki-67 was assessed using the H-score method. Results: BAX immunoreactivity was detected in all age groups. Moderate expression occurred in both neonatal subgroups and the 6–12-month group, while strong expression occurred in the 2–6-month group. Ki-67 immunoreactivity was present in lymphoid and stromal populations, with moderate lymphocyte expression at 2–6 months and the most pronounced overall expression at 6–12 months. Conclusion: Fatal measles in infancy was associated with age-related differences in BAX and Ki-67 expression, indicating differing patterns of pro-apoptotic and proliferative activity across the examined age groups.