Phagolysosome formation upon uptake of C albicans by human neutrophils. (A) CARD9-deficient and control neutrophils were cocultured overnight with unopsonized C albicans. Ultrastructural analysis was performed by EM. EM pictures showed bulging phagolysosome formation upon uptake of C albicans in the patient neutrophils in contrast to the control neutrophils, obtained in 3 independent experiments. (B) The ratio of Candida conidia diameter to the phagosomal space diameter is significantly reduced in CARD9-deficient neutrophils, taking into consideration that the diameter of the Candida conidia was significantly increased in the case of CARD9 deficiency compared with the control (1.3 ± 0.2 μm vs 0.8 ± 0.1 μm; P < .05). Moreover, the phagosomes of CARD9-deficient neutrophils contained more Candida conidia than the control neutrophils (1.5 ± 0.1 vs 1.1 ± 0.1 conidia/phagosome, P < .05). Taken together, the phagosomes of the CARD9-deficient patient have a strongly enlarged appearance. Results are means ± SEM of measurement from 3 independent experiments; **P < .001.