IL2 and Chediak-Higashi syndrome: Congruently, in a cohort of 12 CHS patients, Jessen and colleagues found that late or no onset of HLH in CHS patients correlated with less impaired cytotoxicity of day 7 phytohemagglutinin (PHA)/IL-2 blast T cells, whereas fresh NK cell exocytosis was abnormal in all patients and, therefore, not predictive (20).