Nature of T Lymphocyte Recognition of Macrophage-Associated Antigens

Abstract

Strain 2, strain 13, or (2 × 13)F1 guinea pigs were immunized with human fibrinopeptide B, a 14 amino acid thrombin-derived fragment of the Bβ chain of fibrinogen (Bβ1-14), or the Bβ1-13 homologue, and in vitro T lymphocyte responsiveness was determined by the incorporation of 3H-thymidine. T cells from strain 2 or (2 × 13)F1 animals immunized with Bβ1-14 showed proliferative responses with Bβ1-14 but were unresponsive with Bβ1-13. Bβ1-13, Strain 13 Bβ1-14 immune T cells were unresponsive with both Bβ1-14 and 1–13. By contrast, T cells from strain 13 or (2 × 13)F1 guinea pigs immunized with Bβ1-13 produced proliferative responses with Bβ1-13 but not with Bβ1-14. Strain 2 Bβ1-13 immune T cells showed minimal or no responsiveness with Bβ1-13 or 1–14. Thus, responsiveness to Bβ1-14 is associated with strain 2 animals, and responsiveness to Bβ1-13 is associated with strain 13 guinea pigs. To determine the role of macrophages in presentation of Bβ1-14 or 1–13, T cells from (2 × 13)F1 guinea pigs immunized with Bβ1-14 or 1–13 were stimulated by antigen in association with macrophages derived from either parent. F1 T cells immunized with Bβ1-14 responded to Bβ1-14 in association with only strain 2 but not strain 13 macrophages. By contrast, Bβ1-13 immune F1 T cells responded with Bβ1-13 in association with only strain 13 but not strain 2 macrophages. These results are discussed with respect to the role of macrophages in selecting immunogenic determinants of peptide antigens for presentation to T cells.