Single Degranulations in NK Cells Can Mediate Target Cell Killing.

NK cells are cytotoxic lymphocytes important in defense against viral infection and cancer. NK cells mediate cytotoxicity predominantly through directed secretion of lytic granules, which are specialized lysosome-related organelles, containing effector molecules such as perforin and granzymes. Although many requirements for lytic granule transport to, and secretion at, the NK cell lytic synapse are known, the minimum number of degranulation events required by an NK cell to kill its target is unknown.

Phase I trial of low-dose interleukin 2 therapy in patients with Wiskott-Aldrich syndrome.

Background: Low dose IL-2 can restore the function of T and NK cells from Wiskott-Aldrich (WAS) patients. However, the safety of in vivo IL-2 in WAS is unknown.

Objectives: A phase-I study to assess safety of low dose IL-2 in WAS.

IL-2 in the tumor microenvironment is necessary for Wiskott-Aldrich syndrome protein deficient NK cells to respond to tumors in vivo.

To kill target cells, natural killer (NK) cells organize signaling from activating and inhibitory receptors to form a lytic synapse. Wiskott-Aldrich syndrome (WAS) patients have loss-of-function mutations in the actin regulator WASp and suffer from immunodeficiency with increased risk to develop lymphoreticular malignancies. NK cells from WAS patients fail to form lytic synapses, however, the functional outcome in vivo remains unknown.