Impaired NK-cell and CTL degranulation in patients with immunodeficiency and albinism. Results of CD107a degranulation assays using resting NK cells (A), IL-2–activated NK cells (B), or short-term CTL blasts (C) from patients with CHS (triangles) and GS2 (circles). Closed symbols represent patients manifesting with HLH before age 2; open symbols indicate manifestation of HLH after age 2. For additional explanations, see legend to Figure 2.