MICROFILARIAL CLEARANCE IN LOIASIS INVOLVES ELEVATION OF TH1 AND TH2 PRODUCTS AND EMERGENCE OF A SPECIFIC PATTERN OF T-CELL POPULATIONS

Diethylcarbamazine (DEC) induced clearance of microfilaraemia in losia sis is associated with severe posttreatment reactions. To define the s witch from hypo- to hyperresponsiveness associated with DEC treatment, phenotypic alterations of T-lymphocytes, characterized by flow cytome try, and cytokines, determined by enzyme linked immunosorbent assay, w ere monitored ina microfilaraemic patient. In contrast to reports on o nchocerciasis and lymphatic filariases, no elevation of interleukin (I L)-6 and tumour necrosis factor (TNF)-alpha was observed. The most sev ere side effects conincided with an elevation of interferon (IFN)-gamm a on day 3, followed by IL-10, transforming growth factor (TGF)-beta 2 and macrophage inflammatory protein-1 alpha (MIP-1 alpha) peaking on day 5. Phenotypically, T-cell activation markers CD38, CD54 adn CD25 w ere significantly expressed before treatment, with high CD38 expressio n still existing one year after clearance of microfilaraemia. Treatmen t-related increases were observed with anti-CD122, anti-HLA-DR and ant i-CD69. CD28 was expressed before treatment on almost 100% of CD4(+) a nd CD8(+) T cells and dropped to 20% by day 5, reaching again baseline levels on day 21. Furthermore, there emerged 20% TCR alpha beta-/CD3( +) T cells and 10% anti-beta V5(c)(+) T cells, altogether indicating a specific pattern of T-helper (TH)1 and Th2 cytokines as well as expan sion of certain pauciclonal T-cell populations in response of microfil arial clearance.