The leukocyte functional associated antigen-1 (LFA-1)-intercellular adhesion molecule-1 (CD11a-CD18/CD54) intercellular adhesion system plays a crucial role in several immunologic phenomena, including adhesion between lymphocytes and epithelial cells. In previous studies evidence for CD54 expression on thyroid follicular cells in Hashimoto's
thyroiditis was provided. In this study we evaluated the possible expression of CD11a and
CD18 antigens on thyrocytes of patients with Hashimoto's
thyroiditis and on thyrocytes of patients with
Graves' disease and
simple goiter as controls; we used both
alkaline phosphatase immunostaining and indirect immunofluorescence on cryostatic tissue sections. The results showed that
LFA-1 (both CD11a and CD18) positivity on thyroid follicles may occur in glands of patients with
Hashimoto's disease, with a pattern very similar to that of CD54: this was observed in five of seven specimens. Conversely, no positivity was observed in tissues from patients with
Graves' disease or
goiter: notably, isolated follicular cells from Graves'
goiter tissues are induced in culture to express CD54, but not
LFA-1. Using double-staining techniques, we were able to show that in specimens from patients with
Hashimoto's disease, the same follicular structures coexpressed
LFA-1 and CD54. Such a coexpression of the two
ligands further emphasizes the possible role of this adhesion system in the pathogenesis of epithelial damage, through bidirectional interactions between thyroid epithelial cells and infiltrating
LFA-1 or CD54-positive mononuclear cells.