iNKT Cell Frequency in Peripheral Blood of Caucasian Children and Adolescent: The Absolute iNKT Cell Count is Stable from Birth to Adulthood

Human invariant natural killer T cells (iNKT cells) are a unique population of T cells that express a semi-invariantly rearranged T cell receptor (TCR) and are involved in a variety of immunoregulatory processes. We assessed the frequency of peripheral blood iNKT cells in 64 healthy Caucasian children from 7 months to 18 years of age and five cord blood samples by flow cytometry. iNKT cells were measured as CD3(+) cells co-expressing TCRV alpha 24 and TCRV beta 11 and using the monoclonal antibody 6B11, which recognizes specifically their invariant TCR rearrangement. The absolute number of iNKT cells ranged from 86 to 10,499 (CD3(+)/TCRV alpha 24(+)/ TCRV beta 11(+)) and 233 to 11,167 (CD3(+)/6B11(+)) iNKT cells per millilitre of blood. This range is stable from birth to adulthood. The relative iNKT cell count was found to be 0.003-0.71% (CD3(+)/TCRV alpha 24/TCRV beta 11) and 0.019-0.776% (CD3/6B11) of peripheral blood T cells and shows only a slight increase with age.