An intracellular adaptor protein is indispensable for the development of natural killer T (NKT) cells, according to Pasquier et al. (page 695). The loss of these cells might contribute to the genesis of a lethal immunodeficiency syndrome.
The adaptor protein in question—SAP (SLAM-associated protein)—is expressed in T, NK, and NKT cells and responds to SLAM family receptors by recruiting and activating the downstream tyrosine kinase Fyn. Fyn was known to be required for NKT cell development in the thymus, but the upstream cell surface signals remained unknown.
Pasquier and colleagues now implicate the SLAM family of receptors in NKT cell development by showing that the loss of SAP results in a complete absence of NKT cells in both mice and humans. SAP-transmitted signaling events were uniquely required for the development of NKT cells, as conventional T cells and NK cells developed normally in...
