T-cell-activating monoclonal antibodies, reacting with both leukocytes anderythrocytes, recognize the guinea pig Thy-1 differentiation antigen: Characterization and cloning of guinea pig CD90
H. Schafer et al., T-cell-activating monoclonal antibodies, reacting with both leukocytes anderythrocytes, recognize the guinea pig Thy-1 differentiation antigen: Characterization and cloning of guinea pig CD90, CELL IMMUN, 197(2), 1999, pp. 116-128
A glycophosphatidylinositol (GPI)-linked differentiation antigen expressed
on guinea pig T and B lymphocytes was identified by several monoclonal anti
bodies; it has been shown previously that this membrane protein induced str
ong polyclonal T cell proliferation upon antibody binding and costimulation
by PMA. Purification by immunoadsorption and microsequencing revealed that
this T-cell-activating protein is the homologue of Thy-1 or CD90, In contr
ast to the Thy-1 antigen of most other species, guinea pig Thy-1 has a much
higher molecular weight, which is due to a more extensive N-linked glycosy
lation, bringing the molecular weight of the total antigen up to 36 kDa. Mo
lecular cloning of guinea pig Thy-1 indicated that the deduced molecular we
ight of the protein backbone is 12,777 after removal of an N-terminal 19-am
ino-acid leader peptide and cleavage of the 31 amino acids for GPI anchorin
g the C-terminal end. Sequence comparison showed that guinea pig Thy-1 has
an 82% homology to human and a 72% homology to mouse Thy-1 on the amino aci
d level. Immunohistological staining of cryostat sections revealed intensiv
e staining with the monoclonal antibody H154 on fibroblasts, fibrocytes, Ku
pffer cells, alveolar macrophages, and mesangial cells. As observed in the
human, mouse, and rat, Thy-1 is abundant in the guinea pig brain. Unlike Th
y-1 expression in other species, guinea pig Thy-1 is strongly expressed on
most resting, nonactivated B cells and, to a lesser extent, on erythrocytes
, While treatment of erythrocytes and lymphocytes with GPI-specific phospho
lipase C largely decreased reactivity with mAb H154, T cells retained the p
roliferative response to antibody and phorbol esters. (C) 1999 Academic Pre
ss.