Recurrent Cutaneous Mycobacterium chelonae Infection With an IgM-Predominant Antibody Response in DiGeorge Syndrome.

A young girl with DiGeorge syndrome developed recurrent cutaneous infection caused by Mycobacterium chelonae infection while receiving immunosuppressive therapy. Immunological evaluation demonstrated reduced T-cell proportions and impaired humoral immunity. Western blot analysis using recurrence-phase serum showed IgM reactivity against the recurrent isolate but no detectable IgG reactivity. These findings suggest impaired T-cell-dependent class-switch recombination, resulting in an IgM-predominant humoral response in DiGeorge syndrome.