EBV transformed B cell lines present to antigen specific T cell clones determinants different from those recognized by antibody in an HLA-DR linked restricted fashion

Human B cells nonspecifically activated by Epstein Barr virus (EBV) can present tetanus toxoid (TT) antigen to TT specific helper T cell lines and T cell clones. Presentation of TT antigen by EBV-B cells did not require the presence of TT specific B cells and did not involve B cell surface immunoglobulins. Immunosorbent purified antibody to TT added in great excess to EBV-B cells pulsed with TT for 18 hr did not inhibit the capacity of the EBV-B cells to present TT antigen. Furthermore, EBV-B cells induced proliferation in T cells in the presence of urea denatured TT which contained less than 1% TT reactive with serum anti TT antibody. Studies of TT presentation by a panel of EBV-B cells obtained from HLA typed donors indicated that T cell recognition of TT presented by EBV-B cells was MHC restricted by products of the HLA-D region and some of which differed from serologically defined HLA-DR. These results indicate that the immunogenic moiety presented by EBV activated human B cells consists of antigenic determinants, which differ from those recognized by serum antibody, and of HLA-DR linked MHC determinants. This moiety is similar to that presented by monocytes. The implications of these findings for the amplification of the immune response by activated B cells are discussed.