COMPARISON OF THE IMMUNOHISTOLOGY OF MUCOSA-ASSOCIATED LYMPHOID-TISSUE IN THE LARYNX AND LUNGS IN CASES OF SUDDEN INFANT DEATH AND CONTROLS

The respiratory tract of children in the first two years of life, unli ke that of adults, contains bronchus-associated lymphoid tissue (BALT) and larynx-associated lymphoid tissue (LALT) with no differences in f requency between SID and control children. Using immunohistochemical m ethods we examined the distribution of B, T, CD4(+) and CD8(+) lymphoc ytes, HLA-D+ cells, CD68(+) macrophages and proliferating cells, compa ring bronchus-associated and larynx-associated lymphoid tissue of sudd en infant death cases and controls. In all groups the lymphoid tissue was organized in lymphoid follicles and parafollicular areas. With no differences in the cellular composition of BALT and LALT the lymphoid follicles contained mainly B lymphocytes with some CD4(+) lymphocytes in the germinal centers. Remarkably T lymphocytes of both subset types and B lymphocytes were observed in equal numbers in the parafollicula r ar eas in contrast to gut-associated lymphoid tissue. However, the r espiratory tract of young children with no differences between SID and controls might play a similar role in mucosal immunity and might func tion as an inductive site.