Open AccessExpression of functionally active α 4 β 1 integrin by thymic epithelial cells
Author(s) -
NIETO M.,
GÓMEZ M.,
SÁNCHEZMATEOS P.,
FERNÁNDEZ E.,
MARAZUELA M.,
SACEDÓN R.,
VARAS A.,
GONZÁLEZAMARO R.,
ZAPATA A. G.,
TORIBIO M. L.,
SÁNCHEZMADRID F.
Publication year - 1996
Publication title -
clinical & experimental immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.329
H-Index - 135
eISSN - 1365-2249
pISSN - 0009-9104
DOI - 10.1046/j.1365-2249.1996.d01-819.x
Subject(s) - integrin , biology , microbiology and biotechnology , epitope , alpha chain , cell adhesion molecule , flow cytometry , cell culture , epithelium , alpha (finance) , fibronectin , immunoprecipitation , vinculin , antibody , immunology , cell , receptor , signal transduction , focal adhesion , extracellular matrix , biochemistry , medicine , construct validity , nursing , patient satisfaction , genetics
We have investigated the expression and function of the VLA‐4 heterodimer α 4 β 1 , a member of the β 1 integrin subfamily, on human thymic epithelial cells (TEC) derived from cortical epithelium. The expression of the α 4 integrin chain was studied in four different cloned TEC lines derived from either fetal or post‐natal human thymus by both flow cytometry and immunoprecipitation techniques with anti‐α 4 MoAbs. All different cell lines assayed expressed significant levels of α 4 , as revealed by their reactivity with MoAbs specific for distinct α 4 epitopes. The α 4 subunit expressed by TEC was associated to β 1 but not to β 7 chain, and displayed the characteristic 80/70 kD pattern of proteolytic cleavage. The VLA‐4 integrin in these cells was constitutively active in terms of adhesiveness to both fibronectin and vascular cell adhesion molecule‐1 (VCAM‐1). In addition, this heterodimer localized to punctate regions of the cell in the area of contact with the substratum, named point contacts assessed by staining with the anti‐β 1 activation epitope 15/7 MoAb. According to the cortical origin of the TEC lines expressing VLA‐4, human thymus sections stained with different anti‐α 4 antibodies revealed the presence of cortical, and in smaller numbers medullary epithelial cells bearing α 4 integrin. The expression of α 4 in the thymus was also found in both adult and fetal rats, in which epithelial cells were also specifically stained. Altogether, our data show that VLA‐4 is an additional component of the integrin repertoire of TEC, and suggest that it could have an important role in thymus epithelial cell–thymocyte interactions.