Defective degranulation downstream of ITAM-based receptors in CD45-deficient NK cells. Enriched WT or CD45-deficient NK cells were incubated on plates coated with the indicated mAbs or with PMA (25 ng/mL) and ionomycin (1 μg/mL). Gated on NK1.1⁺CD3⁻ cells. (A) Intracellular staining for IFNγ after incubation with brefeldin A. (B-C) Incubation was performed in the presence of anti-CD107a mAb whereby only those cells that degranulate stained positively for CD107a. Graphs show the average ± SEM of 2-4 experiments using 4-9 mice per genotype. The P values for significant differences between genotypes are located above each condition in each graph. NS indicates no significant differences between genotypes were found using a 2-tailed unpaired t test.