A previously unrecognized site of local accumulation of mononuclear cells:the vascular-associated lymphoid tissue

In recent years our laboratory has developed an immunological hypothesis fo r the pathogenesis of atherosclerosis. We have shown that cellular and humo ral immune reactions against heat shock proteins (Hsps) 60/65 expressed on the surface of stressed endothelial cells comprise the initial event in the pathogenesis of this disease. In the course of these studies, we also inve stigated normal, unaffected arteries for control purposes (carotid bifurcat ions from children aged 8 weeks to 10 years). This investigation led to the unexpected and previously unknown finding that mononuclear cells pre-exist in the intima at bifurcation sites. Our findings can be summarized as foll ows: Mononuclear cells are always found in the intima, primarily at sites s ubjected to major hemodynamic stress. Although the proportion of macrophage s vs CD3(+) T-cells differs, overall the latter clearly predominate. Most o f the T-cells express the T-cell receptor (TCR)alpha/beta, butTCR gamma/del ta cells are also present. We also identified dendritic cells and mast cell s in the intima. Analogous to the mucosa-associated lymphoid tissue (MALT) we coined the designation "vascular-associated lymphoid tissue" (VALT) for these newly discovered cellular aggregates in the arterial intima.