Histopaghologic Finding and Modulation of Expression of The Cell Surface Molecules in The Primary Syphilitic Sedions of a Rabbit Infected with Treponema pallidum

Lee, Ho Jung; Moon, Tae Kee; Lee, Min Geol; Lee, Jung Bock

Abstract

BACKGROUND: When T. pallidum invades through skin and mucous membrane, there may be some changes in the expression of cell surface molecules and cell adhesion molecules on the keratinocytes and vascular endothelial cells.
OBJECTIVES
The purpose of this study was to investigate histologic changes and changes in the expression of cell surface molecules and cell adhesion molecules on the keratinocytes and vascular endothelial cells according to the time course of primary syphilic lesion.
METHODS
We obtained primary syphilitic lesions by inoculation of T. pallidum into the back skin of the rabbit. Biopsies of the syphilitic lesions were performed according to the stages. and H&E and immunohistochemical stains for cell surface molecules were done.
RESULTS
1. Out of the 39 injected sites(103 T. pallidum were inoculated into the back skin of the rabbit), 24(61.5%) primary syphilitic lesion could be found. The duration for the developement of papules, ulcers, and softenings is an average 15 days, 27 days, and 47 days respectively. 2. H & E findings :Acanthosis, spongiosis, and exocytosis in the epidermis were observed in the papule of the primary syphilitic lesion. Infiltration of inflammatory cells, including many lymphocytes, a few histiocytes and plasma cells was also observed. Some cases showed endothelial cell swelling of vessels. Compared to papules, the number of lymphocytes in the ulcer reduced but the number of histiocytes increased. Softened lesion showed infiltrating cells, consisted of lymphocytes and histiocytes, and fibrosis. 3. Immunohistochemical findings :Keratinocytes of the lower epidermis, upper portion of hair follicles, vessel, and infiltrating inflammatory cells in papules and ulcers showed expression of the MHC class II molecule. Most of the infiltrating cells in all cases of papules showed CD5 expression. Keratinocytes, inflammatory cells, and vascular endothelial cells showed positive reaction to ICAM-1 stain in papules and ulcers. VCAM-1 showed the positive reaction to the vascular endothelial cells in the papules and ulcers. In softened lesions, the intensity of the positive reaction to MHC class II, ICAM-1 and VCAM-1 was weakened.
CONCLUSION
The skin of the rabbit which was invaded by T. pallidum increased the expression of the cell surface molecules and cell adhesion molecules of MHC class I, MHC class II, ICAM-1, and VCAM-1. We believe that these expressions of cell surface molecules and cell adhesion molecules by T. pallidum, inflammatory cells, activated keratinocytes, and vascular endothelial cells play important roles in the host defence mechanism and the T. pallidum infection.