Objectives:

In this study, we report the findings of DOCK8 detected by flow cytometry in patients diagnosed with hyperimmunoglobulin E syndrome (HIES).

Patients and methods:

DOCK8 expression in T cells of peripheral blood samples with heparin obtained from 10 HIES patients (1 girl, 9 males; mean age 11.60±3.17 years) and seven healthy controls (2 girls, 5 males; mean age 31.14±19.31 years) were stained using anti-CD3PE, anti-DOCK8, anti-mouse IgG1FITC, and mouse IgG1FITC monoclonal antibodies through the intracellular staining technique. For intracellular staining, two fixation-permeabilization kits (BD-Pharmingen and Invitrogen) from different manufacturers were used. Detection of DOCK8 level was measured in whole blood (WB) and peripheral blood mononuclear cell (PBMC) samples by flow cytometry. DOCK8 level was calculated as mean fluorescence intensity (MFI), MFI-minus (M), and MFI-index (I) according to the isotype.

Results:

The immunoglobulin (IgE) levels of HIES patients were 10032.50±9454.02 IU/mL. DOCK8 deficiency was not found by flow cytometry. Comparison of WB and PBMC results using BD-Pharmingen and Invitrogen fix-perm kit revealed significant differences in MFI and MFI-F values of DOCK8 expression (p=0.004, p=0.006, p=0.012, p=0.012, respectively).

Conclusion:

Mean fluorescence intensity is important to detect the differences of DOCK8 expression in HIES patients. Compared to PBMC, WB should be preferred due to increased DOCK8 expression by flow cytometer. Our study findings support that WB methods can be used for the detection of DOCK8. Mutations in DOCK8 gene should be determined by genetic testing.

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