This is pilot study aimed to investigate the application of proteosome inhibitor, Bortezomib in treatment of patients with neutralizing autoantibody to IFN-γ. The investigators hypothesis is that bortezomib will reduce the antibody level and restore interferon-gamma function, resulting in clinical improvement and should be well-tolerated and safe for use in patients with autoantibody to IFN-γ.

The patients with autoantibody to IFN-γ and past or current history of proven opportunistic infection will receive 2 treatment cycles of bortezomib subcutaneously (4 injections of 1.3 mg Bortezomib /m2 body surface per cycle), followed by low dose oral cyclophosphamide for 4 month after completion treatment with bortezomib.

Inclusion Criteria:

• Age 21 - 60 years
• Positive anti-interferon-gamma autoantibody
• Anti-HIV negative
• Past or current infection with opportunistic infection (OI) such as nontuberculous mycobacteria, proven by culture
• Ability to give written consent, informed written consent
• Negative pregnancy test in premenopausal woman
• Receving antimicrobial for treatment of OI for at least one month.

Exclusion Criteria:

• Pregnancy or lactation
• Absolute neutrophil count <1.5 × 109/ L or platelet count <100× 109/ L or hemoglobin level < 8 g/dL
• Past history of myocardial infarction or heart failure within 6 months before enrollment or prolonged QT interval > 450 msec at screening
• Renal insufficiency (GFR < 30 ml/min)
• Abnormal liver function test (AST> 3 times of UNL)
• Known cancer or receiving other immunosuppressive agent
• Known intolerability to Bortezomib