抗原特異的B細胞を用いた抗原提示に関する基礎的研究

Abstract

We have studied the function of antigen specific immunoglobulin (Ig) receptors in antigen presentation. Monoclonal B cell lines expressing antigen specific surface IgM, IgD or IgG were established by transferring the gene encoding heavy (μ, δ or γ) and light (κ) chains specific for the hapten 2, 4, 6-trinitropheny (TNP) into Ⅰa bearing B cell lymphoma A 20-2 J and WEHI 279 lines. Transfectants were compared in a quantitative assay for the ability to present TNP-carrier to carrier-specific T helper (Th) cells. The A 20-2 J-derived transfectants expressing μκтɴр, δκтɴр or γκтɴр had similiar amounts of the TNP-specific idiotype on their surface and showed an equal capacity to present antigen, which was about 1000-fold more efficient than that of the parental line. However, the γκтɴр transfectant of WEHI 279 line expressed lower amounts of the idiotype than μκтɴр or δκтɴр transfectant and exhibited a decreased capacity of antigen presentation. It was suggested that the antigen presenting capacity of antigen-specific B cells depends on the amount of the idiotype expressed, regardless of its Ig isotype. In addition, a Th hybridoma line used in this study exhibited cytotoxic activity to antigen presenting cell as well as IL-2 production when it was activated. Interestingly, cytotoxicities were also found to NK-resistant cells and to human tumor cells. The target recognition of Th cells was supposed to be different from that of NK cells or cytotoxic T cells.