Blood, Vol. 92 No. 8 (October 15), 1998:
pp. 2815-2822
RP105 Is Associated With MD-1 and Transmits an Activation Signal
in Human B Cells
Yoshihiro Miura,
Rintaro Shimazu,
Kensuke Miyake,
Sachiko Akashi,
Hirotaka Ogata,
Yoshio Yamashita,
Yutaka Narisawa, and
Masao Kimoto
From the Department of Immunology and the Division of Dermatology in
the Department of Internal Medicine, Saga Medical School, Saga, Japan.
RP105 was originally discovered as a mouse B-cell surface molecule
that transmits an activation signal. The signal leads to resistance
against irradiation-induced apoptosis and massive B-cell proliferation.
Recently, we found that mouse RP105 is associated with another
molecule, MD-1. We have isolated here the human MD-1 cDNA. We show that
human MD-1 is also associated with human RP105 and has an important
role in cell surface expression of RP105. We also describe a monoclonal
antibody (MoAb) that recognizes human RP105. Expression of RP105 is
restricted to CD19+ B cells. Histological studies showed
that RP105 is expressed mainly on mature B cells in mantle zones.
Germinal center cells are either dull or negative. RP105 is thus a
novel human B-cell marker that is preferentially expressed on mature B
cells. Moreover, the anti-RP105 MoAb activates B cells, leading to
increases in cell size, expression of a costimulatory molecule CD80,
and DNA synthesis. The B-cell activation pathway using RP105 is
conserved in humans.
© 1998 by The American Society of Hematology.
