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Title
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Cloning, mapping, and characterization of activated leukocyte-cell adhesion molecule (ALCAM), a CD6 ligand.
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Authors
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M.A.Bowen,
D.D.Patel,
X.Li,
B.Modrell,
A.R.Malacko,
W.C.Wang,
H.Marquardt,
M.Neubauer,
J.M.Pesando,
U.Francke.
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Ref.
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J Exp Med, 1995,
181,
2213-2220.
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PubMed id
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Abstract
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Antibody-blocking studies have demonstrated the role of CD6 in thymocyte-thymic
epithelial (TE) cell adhesion. Here we report that CD6 expressed by COS cells
mediates adhesion to TE cells and that this interaction is specifically blocked
with an anti-CD6 monoclonal antibody (mAb) or with a mAb (J4-81) that recognized
a TE cell antigen. We isolated and expressed a cDNA clone encoding this antigen
and show that COS cells transfected with this cDNA bind a CD6 immunoglobulin
fusion protein (CD6-Rg). This antigen, which we named ALCAM (activated
leukocyte-cell adhesion molecule) because of its expression on activated
leukocytes, appears to be the human homologue of the chicken neural adhesion
molecule BEN/SC-1/DM-GRASP. The gene was mapped to human chromosome 3q13.1-q13.2
by fluorescence in situ hybridization of cDNA probes to metaphase chromosomes.
We prepared an ALCAM-Rg fusion protein and showed that it binds to COS cell
transfectants expressing CD6, demonstrating that ALCAM is a CD6 ligand. The
observations that ALCAM is also expressed by activated leukocytes and that both
ALCAM and CD6 are expressed in the brain suggest that ALCAM-CD6 interactions may
play a role in the binding of T and B cells to activated leukocytes, as well as
in interactions between cells of the nervous system.
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