A non-HIV case with disseminated Mycobacterium kansasii disease associated with strong neutralizing autoantibody to interferon-γ.

Disseminated non-tuberculous mycobacterium (dNTM) infection is rare in humans without human immunodeficiency virus (HIV) infection. Previous reports have shown autoantibodies to human interferon-gamma (IFN-γ), which play important roles in mycobacterium infection, in the sera of patients with non-HIV dNTM disease. Herein, we describe a 53-year-old male who was strongly suspected to have multicentric Castleman disease (MCD) based on bone marrow study and chest radiological findings. However, Mycobacterium kansasii was detected in respiratory samples including pleural effusion. We initiated anti-mycobacterial therapy under intensive care; he died on the 48(th) hospital day. We detected no hematological disorders, ruling out MCD postmortem. However, we detected M. kansasii in pulmonary, liver, spleen and bone marrow tissues. Moreover, anti-IFN-γ autoantibody was detected with strong neutralizing capacity for IFN-γ. We consider our present report to contribute to understanding of the relationship between anti-IFN-γ autoantibody and disease development.