Rabbit Antithymocyte Globulin Causes Blastomyces and Histoplasma Antigenemia

Area of Science:

• Medical Mycology
• Transplant Immunology
• Clinical Diagnostics

Background:

• Rabbit antithymocyte globulin (rATG) is frequently used in organ transplantation.
• rATG is a known cause of false-positive results for Histoplasma antigenemia.
• Modified antigen assays aim to mitigate rATG interference.

Purpose of the Study:

• To report a case of rATG-induced false-positive antigenemia.
• To investigate the efficacy of modified antigen assays in a clinical setting.

Main Methods:

• Case report of a lung transplant recipient.
• Utilized fourth-generation MiraVista Histoplasma antigen assay, modified to block rATG effects.
• Monitored for Blastomyces and Histoplasma antigenemia.

Main Results:

• The patient experienced false-positive Histoplasma antigenemia.
• False-positive Blastomyces antigenemia was also detected.
• These false positives occurred despite the use of modified antigen assays.

Conclusions:

• rATG can induce false-positive results for both Histoplasma and Blastomyces antigenemia.
• Modified antigen assays may not fully eliminate rATG interference.
• Careful interpretation of antigenemia results in patients receiving rATG is crucial.