T cell clones which share T cell receptor epitopes differ in phenotype, function and specificity.

Recently, we described a monoclonal antibody (3D6) that reacts with the T cell receptor (Ti) of the T leukemic cell line HPB-ALL and that cross-reacts with 2-10% of the T cells of normal healthy individuals. In this study we report the establishment of T cell clones that are 3D6+ but that differ in function and phenotype. These clones were established according to two different protocols: T cells of donor HY (10% 3D6+) were stimulated with the Epstein-Barr virus-transformed cell line JY. The proliferating 3D6+ T cells were enriched using a rosetting technique and cloned. T cells of donor HY were stimulated with the 3D6 antibody and subsequently expanded in recombinant interleukin 2-containing medium. This yielded 70% 3D6+ T cells which after activation with either Daudi cells or with TT in the presence of autologous non-T cells, followed by cloning, resulted in antigen-specific 3D6+ T cell clones. The 3D6+ T cell clones were also tested on their reactivity with 4 other monoclonal antibodies (1C1, 1C2, 2D4, 65) specific for the Ti of HPB-ALL. The antibodies 1C1 and 1C2 reacted with all 3D6+ T cell clones and recognize probably the same epitope as 3D6. The antibodies 2D4 and 65 reacted with two mutually exclusive subsets of T cell clones. All the anti-Ti antibodies reacted with functional epitopes, since they were able to block the function of the T cell clones. The specificity of the clones was investigated by blocking studies using monoclonal antibodies specific for different major histocompatibility complex antigens. No correlation was found between the expression of the different Ti epitopes and the specificity, the CD4/CD8 phenotype or function of the clones.