Human influenza virus-specific T helper cell clones can be restricted by MHC products different from serologically defined HLA-DR antigens.

Clones of human influenza A virus-specific T lymphocytes were generated by limiting dilution after several in vitro stimulations with autologous influenza A/USSR virus-infected cells. The clones were expanded in T cell growth factor and then grown only in the presence of antigen and irradiated stimulator cells. The clones showed antigen specificity in that they were stimulated only by cells infected with influenza A virus, but not with influenza B virus; some clones even showed distinct reactivity patterns with several influenza A virus subtypes. All clones had the OKT3+4+8-phenotype. Analysis of the restriction elements for the recognition of viral antigens, demonstrated that most clones recognized antigens associated with but not identical to serologically defined HLA-DR specificities. From the recognition pattern with HLA-DR typed donors, three different restricting antigens could be demonstrated.