Fibronectin associated with infiltrating T lymphocytes. Evidence for <i>in situ</i> localization in biopsies and synthesis <i>in vitro</i>

Abstract

Dermal and mucosal lymphocyte infiltrates in patients with lichen ruber planus and chronic graft-vs.-host disease exhibited reactivity with anti-fibronectin antibodies. This reactivity was associated with the lymphocytes and localized pericellularly. In contrast, biopsy areas outside lymphocyte accumulations were relatively devoid of reactivity with anti-fibronectin antibodies. Furthermore, the corresponding biopsies from healthy individuals or patients without lymphocyte infiltration showed negligible reactivity with anti-fibronectin antibodies. The fibronectin associated with infiltrating lymphocytes in biopsies may be exogenous of non-lymphoid origin. However, another possibility suggested by in vitro experiments is that this fibronectin is lymphocyte derived. Thus, during cultivation in vitro lymphocytes appear to synthesize a component with fibronectin-like properties. Furthermore, a prerequisite for detection of this synthesis was that the cells were cultured in the presence of serum depleted of fibronectin. These results point to the possibility that fibronectin may play a role for lymphocyte interactions with tissues during infiltrative processes.