Halothane hepatitis. Detection of a constitutional susceptibility factor.

Area of Science:

• Hepatology
• Toxicology
• Immunology

Background:

• Halothane hepatitis is a severe adverse drug reaction.
• The exact mechanism and predisposing factors remain unclear.
• Electrophilic drug metabolites are implicated in liver injury.

Purpose of the Study:

• To investigate in vitro lymphocyte susceptibility to halothane-induced cell damage.
• To identify potential biomarkers for halothane hepatitis susceptibility.

Main Methods:

• An in vitro assay using rat hepatic microsomes and phenytoin was developed.
• Lymphocyte cytotoxicity was measured by trypan blue dye exclusion.
• The assay incorporated 1,1,1-trichloropropene oxide (TCPO) to trap reactive metabolites.

Main Results:

• Lymphocytes from halothane hepatitis patients showed significantly higher cytotoxicity (8x) compared to healthy controls.
• Patients with other liver diseases or recent halothane exposure without adverse effects did not differ from controls.
• The lymphocyte abnormality persisted for at least 13 months in affected patients and was observed in family members.

Conclusions:

• A familial, constitutional susceptibility factor likely predisposes individuals to halothane hepatitis.
• In vitro lymphocyte cytotoxicity assay may identify individuals at risk.
• Further research into the genetic basis of this susceptibility is warranted.