The perforin-staining pattern in 2 parents of patients with HLH and in a patient with hemophagocytic-associated complications.

A healthy adult control (A), a father with a single perforin mutation (B), the mother of patient P11, who had complete perforin deficiency (C), a patient with JRA and MAS (D). (B-C) The perforin positivity of these parents was markedly decreased in CD8⁺ T cells and CD56⁺ T cells. Perforin positivity in NK cells of these parents was slightly decreased and mean channel fluorescence was also low. The patient with JRA and MAS showed a similar pattern.