Thiol-protease inhibitors selectively inhibit presentation of antigen incorporated through B cell antigen receptors.
B cells efficiently uptake exogenous antigens through cell surface IgM molecules and present them to specific T cells. Although it is implicated that antigens taken up by surface IgM associate with newly synthesized class II molecules, the precise pathway of the presentation is still unclear. Here we report that thiol-protease inhibitors inhibit the presentation of trinitrophenol-conjugated ovalbumin by a leukemic B cell line, A20.HL, which constitutively expresses trinitrophenol-specific surface IgM although they had only a minimum effect on the presentation of unconjugated ovalbumin. In addition, thiol-protease inhibitors slightly reduced the surface expression of class II molecules. Our results suggest that exogenous antigen taken up through surface IgM is presented by a pathway which involves proteolysis by thiol-proteases and distinct from that for the antigens taken up through non-specific endocytosis.
Togashi
K
K
Department of Bioengineering, Tokyo Institute of Technology, Yokohama, Japan.
Magae
J
J
Kataoka
T
T
Nagai
K
K
D017951:Antigen Presentation / Q000187:drug effects*; D000941:Antigens / Q000378:metabolism*; D000976:Antipain / Q000494:pharmacology; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology*; D007075:Immunoglobulin M / Q000378:metabolism*; D007976:Leupeptins / Q000494:pharmacology; D008285:Major Histocompatibility Complex; D010873:Pinocytosis; D011947:Receptors, Antigen, B-Cell / Q000187:drug effects* / Q000378:metabolism; D014407:Tumor Cells, Cultured
D000941:Antigens; D015853:Cysteine Proteinase Inhibitors; D007075:Immunoglobulin M; D007976:Leupeptins; D011947:Receptors, Antigen, B-Cell; D000976:Antipain; C032854:leupeptin