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. 2015 Oct 19;7(11):1480–1502. doi: 10.15252/emmm.201505246

Figure 2. NKG2D binding to the MICA-129Met and MICA-129Val isoform and triggering of phosphorylation of SRC family kinases.

Figure 2

  1. The linear regression of MICA expression intensity and binding of a recombinant NKG2D-Fc fusion protein both determined as MFI by flow cytometry is displayed for L-MICA-129Met (n = 79, left panel) and L-MICA-129Val clones (n = 81, right panel). The coefficients of determination (R2), the regression coefficients (reg. coeff.), and the P-values for Pearson correlation are indicated.
  2. Purified IL-2-stimulated (100 U/ml for 4 days) NK cells (106) were stimulated with immobilized MICA-129Met-mIgG2a-Fc or MICA-129Val-mIgG2a-Fc or OVA-mIgG2a-Fc fusion proteins (10 μg/ml) for 3, 10, or 30 min. The protein lysates of these cells were separated by SDS–PAGE, and the blot was probed subsequently with an anti-phospho-Tyr mAb, an anti-phospho-SRC family (Tyr419) kinases Ab, and an anti-β-actin mAb as a loading control. The arrow points toward phosphorylated SRC family kinases.
  3. Blots obtained from three independent experiments were analyzed by densitometry, and the means plus SD of the ratio between phospho-SRC family kinase and β-actin signals is displayed. The difference between NK cells stimulated for 10 min by MICA-129Met-Fc or MICA-129Val-Fc proteins was assessed by t-test.
  4. Purified IL-2-stimulated NK cells (100 U/ml for 4 days, 106) were incubated with the SRC kinase inhibitor PP2 (25 μM), the vehicle DMSO, or medium only (Ø) for 30 min before being added to immobilized MICA-129Met-Fc, MICA-129Val-Fc, or OVA-Fc fusion proteins (10 μg/ml) for 10 min. The protein lysates of these cells were separated by SDS–PAGE, and the blot was probed subsequently with an anti-phospho-Tyr mAb and an anti-β-actin mAb as a loading control. The blot is representative for two independent experiments.
  5. In parallel, degranulation of the NK cells was measured by anti-CD107a staining in flow cytometry. The difference between DMSO- and PP2-treated cells with respect to CD107a+ cells and the MFI of CD107a is indicated in the histograms. The results are representative for two independent experiments.