The first US domestic report of disseminated Mycobacterium avium complex and anti-interferon-γ autoantibodies.

INTRODUCTION

Anti-interferon-γ (IFNγ) autoantibodies have been associated with disseminated mycobacterial infections, mostly in patients from Southeast Asia.

PURPOSE

We studied an American-born, Caucasian female with M. avium complex infection of the subglottic mucosa and brain for underlying etiologies of infection.

METHODS

Plasma was screened for anticytokine autoantibodies using a Luminex-based approach. The ability of patient plasma to block IFNγ-induced STAT1 phosphorylation in normal blood cells was evaluated by flow cytometry with intracellular staining. Plasma inhibition of IFNγ production and IFNγ-induced cytokines in normal and patient blood cells washed of autologous plasma was also evaluated.

RESULTS

Patient plasma contained high-titer IgG anti-IFNγ autoantibodies, primarily of the IgG1 subclass. Patient but not control plasma prevented IFNγ-induced STAT1 phosphorylation and expression of the IFNγ-inducible cytokines tumor necrosis factor (TNF) α and interleukin (IL)-12 in normal blood cells. Patient blood cells washed free of autologous plasma demonstrated normal IFNγ production and response.

CONCLUSIONS

Disseminated nontuberculous mycobacterial infections should always prompt immune evaluation. This first case of disseminated nontuberculous mycobacterial infection and anti-IFNγ autoantibodies in an American-born Caucasian suggests that anti-cytokine autoantibodies are not racially or regionally restricted.