Can urinary gliotoxin or mycophenolic acid impair immune function or indicate a building source?

Context

• Gliotoxin and mycophenolic acid have biologically credible toxicologic and immunologic effects, but a urine finding does not by itself identify where exposure occurred or establish that it explains illness in a 77-year-old man.

Immune and cellular effects

• Gliotoxin experimentally suppresses phagocytosis, neutrophil oxidative killing, NF-κB signaling, and T-cell/dendritic-cell function. Effects have been reported at roughly 92–306 nM in human neutrophils and 0.15–1.5 μM in T-cell experiments.
• Mycophenolic acid (MPA) is an established immunosuppressant. Its principal mechanism is inhibition of inosine monophosphate dehydrogenase (IMPDH), reducing guanine-nucleotide availability and preferentially limiting lymphocyte proliferation.
• These findings establish potential biological activity, not clinical effects at an unquantified environmental exposure level.

Mechanistic evidence

• Gliotoxin can disrupt mitochondrial membrane potential at 300 nM in activated human hepatic stellate cells, followed by cytochrome-c release and caspase-3 activation; Bak-dependent reactive oxygen species generation has also been implicated. Effects vary by cell type: it may reduce neutrophil ROS while promoting oxidative injury in other experimental systems.
• Therapeutic-range mycophenolate mofetil caused mitochondrial depolarization, increased ROS, impaired respiration, and cytochrome-c-associated apoptosis in human T cells in vitro.

Interpretation of urinary testing

• Urine testing cannot determine exposure route, timing, location, absorbed dose, tissue concentration, or symptom causation. There are no validated urine thresholds linking gliotoxin or MPA concentrations to symptoms or immune impairment.
• MPA may reflect prescribed mycophenolate use or dietary sources, including mold-ripened blue cheese; diet and background exposure can also complicate mycotoxin interpretation. A building-specific conclusion requires independent environmental and exposure evidence.

Bottom line

• Both compounds can affect immune and cellular pathways, but urinary detection alone cannot diagnose toxin-related illness, attribute symptoms to these compounds, or prove a building was the exposure source.