Serum levels of soluble Fas/APO-1 receptor in human retroviral infection and associated diseases

Fas/APO-1 mediates apoptosis via Fas and Fas ligand transduction, Recently, a soluble form of Fas (sFas) was described which seems to be functionally implicated in the Fas signal system, suggesting a relationship between some disorders and sFas function, We measured sFas-levels in sera from normal controls and patients with disorders linked to human retroviral infection of human immunodeficiency virus (HIV) and human T-cell leukemia virus type-1 (HTLV-1), The sFas level of normal controls, HTLV-1 carriers seronegative for HIV, and patients with HTLV-1 associated myelopathy/tropical paraparesis (HAM/TSP), adult T-cell leukemia (ATL), and AIDS was 1.62+/-0.49, 1.90+/-0.49, 2.00+/-0.59, 3.32+/-2.05, and 3.06+/-0.92 ng/ml, respectively, Although the level of sFas in patient groups with HAM/TSP, ATL, and AIDS was significantly high in comparison to that of normal controls (p<0.01), the individual values were highly variable within the groups, The sFas level was statistically correlated to the soluble interleukin-2 receptor (sIL-2R) level, as well as to cells expressing membrane Fas (mFas), indicating the same cellular origin, In some ATL cases, however, serum sFas levels and mFas expression density on leukemic T-cells were discrepant, with especially high levels of the soluble form and a lack of expression of the membrane form observed in 2 cases, sFas detection could serve as a putative marker for active diseases in patients with ATL and AIDS.