Characterization of Clozapine-Responsive Human T Cells

Area of Science:

• Immunology
• Pharmacology
• Molecular Biology

Background:

• Clozapine, an atypical antipsychotic, is linked to life-threatening agranulocytosis.
• The immune system is implicated due to delayed onset and association with HLA variants.

Purpose of the Study:

• Generate clozapine-specific T cell clones (TCC).
• Characterize T cell activation pathways and cross-reactivity with clozapine metabolites and olanzapine.

Main Methods:

• Established and characterized TCC from healthy donors and patients with clozapine-induced agranulocytosis.
• Utilized molecular modeling for drug-HLA binding interactions.
• Performed mass spectrometry for global TCC protein profiling.

Main Results:

• Clozapine directly interacts with HLA-DR molecules at therapeutic concentrations, activating TCC.
• Olanzapine activated TCC only at supratherapeutic concentrations.
• Molecular docking revealed distinct binding conformations for clozapine and its metabolites within HLA-DR binding clefts.

Conclusions:

• Clozapine activates human CD4+ T cells via direct interaction with HLA-DR molecules at therapeutic concentrations.
• This activation mechanism contributes to clozapine-induced agranulocytosis.
• Olanzapine exhibits a different T cell activation profile compared to clozapine.