NKT cell subsets in infection and inflammation.

We recently identified two stably expressed cell surface markers, IL-18R and ST2L, which are selectively expressed on T1/NK1 and T2/NK2 cells, respectively. Here we use these molecules in direct ex vivo analysis of PBMCs from patients with AIDS, psoriasis (PS) atherosclerosis and to show the importance of these markers as determinants of the functional dichotomy of lymphocyte subsets, in particular NKT. In a cohort of 22 HIV patients made up of a mixture of long term non-progressors, seroconvertors, progressors and asymptomatics, we found a clear NKT1 to NKT2 shift (P=0.001) in the HIV-infected individuals. We also show a predominance of NKT2 cells over NKT1 cells in the PBMCs of patients with mild to moderate PS (N=13, P=0.005) but not in atopic dermatitis or healthy controls. However, in patients (N=6) requiring surgery for aneurysm, a predominance of Type 1 (IL-18R(+)) NKT lymphocytes over NKT2 was detected among infiltrating lymphocytes isolated from atherosclerotic plaques. Our data therefore demonstrate that ST2L and IL-18R could serve as important determinants of the immune status of human diseases.