The Natural History of X-Linked Lymphoproliferative Disease (XLP1): Lessons from a Long-Term Survivor

Figure 3

NK cell cytotoxicity at age 43. Peripheral blood mononuclear cells (PBMCs) from healthy controls or the patient were used as effector cells and were incubated with target cells. (a) Target cells were the K562 monocytic cell line lacking MHC class I. Spontaneous cytotoxicity against these target cells was measured following a 4-hour stimulation ± IL-2. In the absence of IL-2, to lyse 10% of target cells, the patient sample required 25 NK cells per one target cell (25 : 1, NK: target cell ratio). Comparatively, the control required 19 NK cells per one target cell (19 : 1). In the presence of IL-2, the patient sample required 11 NK cells per one target cell (11 : 1) and the control required 9 NK cells per one target cell (9 : 1). (b) Target cells were human lymphoblast-like Raji B cells that express MHC class I CD19 and CD20. Antibody-dependent NK cell cytotoxicity against these target cells was measured following a 4-hour stimulation ± rituximab. No cytotoxicity was observed in the absence of rituximab. In the presence of rituximab, to lyse 5% of target cells, the patient sample required 97 NK cells per one target cell (97 : 1), whereas the control required 16 NK cells per one target cell (16 : 1). This test was performed in a CLIA-certified laboratory.

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