Membrane expression of HLA-Cw4 free chains in activated T cells of transgenic mice

✍ Scribed by Alessandro Aiuti; Pietro Forte; Luca Simeoni; Maddalena Lino; Laura Pozzi; Andrea Fattorossi; Patrizio Giacomini; Enrico Ginelli; Alberto Beretta; Antonio Siccardi; Antonio Fantoni

• Book ID: 104653001
• Publisher: Springer-Verlag
• Year: 1995
• Tongue: English
• Weight: 932 KB
• Volume: 42
• Category: Article
• ISSN: 0093-7711
• DOI: 10.1007/bf00179398

✦ Synopsis

Transgenic mice were produced in which human HLA-Cw4 is stably integrated, behaves as a single Mendelian trait, and, being under the transcriptional control of human CD2, is selectively and efficiently expressed in T lymphocytes. These mice were used as a model system to determine whether HLA-type C molecules can be exposed on the surface of activated lymphocytes as free heavy chains, non-associated with ~32-microglobulin (132m). In our transgenic mice we could identify HLA-Cw4 molecules either as free chains or as ~2m-associated molecules by the use of monoclonal antibodies specific for either conformation of HLA class I and nonreactive to mouse H2 molecules. Resting mouse lymphocytes were shown by western transfer analysis to contain sizeable amounts of HLA-Cw4 free chains, but they exposed on their surface HLA-Cw4 only in association with [32m, as indicated by flow cytometric measurements. Conversely, where the content of total HLA-Cw4 was increased, lectin-activated mouse lymphocytes exposed on their outer cell membrane HLA-Cw4 molecules in both conformations, namely, also as free heavy chains. Isoelectrofocusing analysis confirmed the presence of both HLA-Cw4 molecular conformations in activated T cells and indicated that HLA-Cw4 heavy chains can bind to mouse 132m with the same low affinity displayed for human [~2m. The results of our experiments led us to