The impact of Secretory Leukoprotease Inhibitor (SLPI) on dendritic cells (DC) phenotype and function

REITERI, M; VILLALONGA, X; COSTA, M; MAFFIA, P; TATEOSIAN, NANCY; CHULUYAN, E

Buenos Aires, Argentina

Congreso; First French Argentine Immunology Congress. LVIII Reunión Anual de la Sociedad Argentina de Inmunología; 2010

Dendritic cells are the main antigen presenting cells that mediate the link between the innate and adaptive immune response. In the tissues, the immature DCs are exposed to a variety of factors. SLPI is a serine protease inhibitor constitutively expressed in the epithelial mucosal lining cells and its expression increases following an inflammatory stimulus. The aim of the present study was to examine the effect of SLPI on immature DCs. For this, DCs were generated from peripheral blood monocytes in the presence of IL-4 and GM-CSF.  DCs were incubated 48 h with rhSLPI (4 ìg/ml) or control buffer and the expression of surface molecules and apoptosis were analyzed by flow cytometry. Also, lymphocyte proliferation induced by SLPI-treated DCs or untreated DCs was analyzed by 3H-Tymidine incorporation. SLPI-treated cells showed an increase of CD83 (8 ± 2%, p<0.05), but not MHC class I and II, CD40, CD80 and CD86. Basal apoptosis of immature DCs was low (12 ± 3%). When DCs were treated with SLPI, early apoptosis was significantly increased (SLPI: 20 ± 4%, p<0,05).  The effect of SLPI on DCs apoptosis was not observed with heat denatured SLPI. Furthermore, SLPI treated-DCs showed higher lymphocyte allogeneic proliferative ability compared to untreated DCs (Control: 23709 ± 2033 cpm; SLPI: 40726 ± 5733 cpm, p<0.05).  The effect of SLPI-treated DCs on lymphocyte proliferation was dose dependent and it was not observed with heat denatured SLPI. These results demonstrate that SLPI modify the phenotype and function of immature DCs. Based on the CD83 expression, the increase in apoptosis and the proliferation, it is probably that SLPI promote the maturation of DCs.