Transporters associated with antigen processing (TAP)-independent presentation of soluble insulin to α/β T cells by the class Ib gene product, Qa-1(b)

S. Mark Tompkins, Jennifer R. Kraft, Chinh T. Dao, Mark J. Soloski, Peter E. Jensen

Research output: Contribution to journalArticle


T cell hybridomas isolated from nonresponder H-2(b) mice immunized with pork insulin were stimulated by insulin in the presence of major histocompatibility complex (MHC)-unmatched antigen presenting cells. The restriction element used by these CD4- T cells was mapped to an oligomorphic MHC class Ib protein encoded in the T region and identified as Qa-1(b) using transfectants. The antigenic determinant was localized to the insulin B chain, and experiments with truncated peptides suggested that it is unexpectedly long, comprising most or all of the 30 amino acid B chain. The antigen processing pathway used to present insulin to the Qa-1(b)-restricted T cells does not require transporters associated with antigen processing (TAP), and it is inhibited by chloroquine. A wide variety of cell lines from different tissues efficiently present soluble insulin to Qa-1(b)-restricted T cells, and insulin presentation is not enhanced by phagocytic stimuli. Our results demonstrate that Qa-1(b) can function to present exogenous protein to T cells in a manner similar to MHC class II molecules. Therefore, this class Ib protein may have access to a novel antigen processing pathway that is not available to class Ia molecules.

Original languageEnglish (US)
Pages (from-to)961-971
Number of pages11
JournalJournal of Experimental Medicine
Issue number5
StatePublished - Sep 7 1998



  • Antigen processing
  • Class Ib molecules
  • Insulin
  • Major histocompatibility proteins
  • T cells

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology

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