Objectives:

This study aims to investigate the role of IL-12Rβ1 expression analysis using flow cytometry for screening patients with mendelian susceptibility to mycobacterial disease (MSMD) and identification of the obligate carriers.

Patients and methods:

Six pediatric patients (2 girls, 4 males; mean age 5 years; range 2 to 10 years) who were admitted to Hacettepe University, Department of Pediatric Immunology, Ankara with clinical signs of MSMD and with proven IL-12Rβ1 deficiency using mutation analysis and 12 parents (obligate carriers) were included in this study. A total of 58 family member and 20 healthy controls were also included. The subjects were screened for IL-12Rβ1 expression analysis using flow cytometry after in vitro stimulation with phytohemagglutinin (PHA) on the surface of peripheral blood lymphocytes.

Results:

The IL-12Rβ1 expression was less than 1% in six patients with clinical signs of MSMD and proven IL-12Rβ1 gene mutation. The mean percentages of lymphocytes expressing IL-12Rβ1 were found to be 85% (71%-98%) and 47% (18%-75%) for the controls and obligate carriers, respectively. The ROC (receiver operating characteristics curve) analysis revealed the percentage of IL-12Rβ1 expressing cells of <1%, <70%, and >76% could be regarded as homozygous IL-12Rβ1 deficient, IL-12Rβ1 carrier and healthy individuals, respectively.

Conclusion:

Our study results suggest that IL-12Rβ1 expression analysis with flow cytometry is an effective method for the screening of the patients with IL-12Rβ1 deficiency, the most common defect of MSMD.

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