TNFalpha Expression in the Paraffin-embedded Tissues of Leprosy

Lee, Ju Eun; Choi, Yoo Won; Choi, Hae Young; Myung, Ki Bum

Abstract

BACKGROUND: Tumor necrosis factor alpha (TNFalpha ) plays various roles in the pathogenesis of leprosy. Expression of TNFalpha according to the clinical type of leprosy has been studied in the patient serum, stimulated PBMC, and the skin lesions, but these results were controversial. Also, all studies of the skin lesions have been limited because of a small number of frozen tissues.
OBJECTIVE
The purposes of this study were to estimate the availability of paraffin-embedded skin tissue of leprosy for the detection of TNFalpha mRNA and protein, to analysis the TNFalpha expression according to the clinical types of leprosy and lepra reaction, and to demonstrate various TNFalpha -positive cells in the skin lesions.
METHODS
In the paraffin-embedded tissues of 17 new cases of leprosy, TNFalpha mRNA expression was detected by in situ hybridization with digoxigenin labelled oligonucleotide probe cocktail and TNFalpha protein expression by immunohistochemical stain. In addition, serum TNFalpha level was estimated by ELISA for the evaluation of the relationship between before and after lepra reaction.
RESULTS
1. The density of TNFalpha mRNA-positive cells ranged from 8 to 26 percent (mean 17 percent) and that of TNFalpha protein-positive cells ranged from 3 to 8 percent (mean 7 percent). They were the highest in borderline lepromatous leprosy lesions. The density of TNFalpha -positive cells was significantly higher by in situ hybridization than by immunohistochemical stain. 2. The TNFalpha -positive cells in paraffin-embedded skin lesion were CD8 positive lymphocytes, CD68 positive macrophages, endothelial cells, histiocytes, Schwann cells, and keratinocytes. The number of these cells before leprosy treatment was not significantly different from that after leprosy treatment. 3. The density of CD8-positive cells was significantly higher in lesions without lepra reaction than in lesions with lepra reaction, and that of CD68-positive cells was significantly higher in lepromatous leprosy lesions than in borderline lepromatous leprosy lesions. 4. Serum TNFalpha level was higher during lepra reaction than before lepra reaction and the high level continued even after resolution of lepra reaction.
CONCLUSION
It suggested that the paraffin-embedded tissue in leprosy is an effective and available material for detecting expression of TNFalpha mRNA and protein. Also, in situ hybridization was more sensitive than immunohistochemical stain. The number of TNFalpha -positive cells was the highest in borderline lepromatous leprosy lesions. With further refinement, this may be an easier application of study for TNFalpha expression in leprosy.