Diallyl disulphide, but not diallyl sulphide, increases leucocyte function-associated antigen-1 expression and cellular adhesion in monocytes

A steam distillation process at pH 9 was conducted to prepare garlic oil for food supplement. A garlic oil predominant in bioactive diallyl monosulphide (8.9%), diallyl disulphide (56.9%) diallyl trisulphide (7.6%) and diallyl tetrasulphide (2.6%) was obtained from peeled garlic cloves. The adhesion molecule leucocyte function-associated antigen-1 (LFA-1) mediates leucocyte adhesion and migration during immune responses. In this study, we investigated the effects of diallyl sulphide (DAS) and diallyl disulphide (DADS) on LFA-1 expression, cell adhesion and migration in the U937 and peritoneal macrophages from mice. After treatment, DADS, but not DAS, elevated the expression of LFA-1 in a dose- and time-dependent manner in U937 cells and peritoneal macrophages. Moreover, LFA-1 and intracellular adhesion molecular-1 (ICAM-1)-mediated adhesion also was increased by DADS in a dose- and time-dependent manner. After DADS treatment, LFA-1 clustering also increased on U937 surface. In contrast, there was no significant difference in migration of U937 cells between DADS treatment and no treatment. This study indicates the DADS, but not DAS, regulates immune responses by modulating LFA-1 expression, clustering and LFA-1-mediated adhesion in monocytes, evidences that DADS acts as an immune regulator of adhesion molecules during immune responses.