Increased Class Ib Antigen Display onTAP-2Mutant Cells by a Mitochondrial Function Inhibitor

Class I histocompatibility antigen display is defective in the RMA-S mutant cell line due to a mutation in theTap-2gene, which encodes a peptide transporter. Incubation of RMA-S cells with oligomycin, an inhibitor of mitochondrial ATPase, strongly increased lysis by cytotoxic T lymphocytes (CTL) specific for the class Ib antigen H2-M3, and lysis by Qa-1b-specific CTL was restored. Oligomycin did not affect normal class I display on RMA cells. Treatment of RMA-S cells with other inhibitors of mitochondrial function failed to increase lysis by anti-H2-M3 or Qa-1bCTL. Lysis by allogenic CTL specific for H-2bantigens was either not enhanced or only weakly increased, depending upon theH-2haplotype of the alloreactive effector cells used.