Expression of Thy-1 and effect of phosphatidylinositol-specific phospholipase C on primate and murine cell lines

BALC/c mice were immunized with isolated human brain Thy-1. The antisera at an appropriate dilution only reacted with a doublet of an apparent molecular weight (MW) around 25,000 among all the glycoproteins of brain tissue isolated by lentil lectin affinity chromatography when tested by enzyme-linked immunosorbent assay and immunoblotting. When the antisera were used to test a number of human cell lines and a marmoset T-cell line (70N2) by flow cytometry, an astrocytoma cell line (U-373), a T-lymphoblastoid cell line (MOLT-3), and two cutaneous T-lymphoma cell lines (HUT-7 8 and HUT-102) as well as the 70N2 cells were stained. However, a B-lymphoma cell line (Raji), a plasmacytoma cell line (HMy2), and normal peripheral blood lymphocytes were negative. When the positive cells were treated with phosphatidylinositol-specific phospholipase C, a significant decrease in both stain intensity and percentage of positive cells was demonstrated by immunofluorescence. Although Thy-1 expression in human lymphoid system is currently thought to be confined in early T- and B-lymphocyte development, our data suggest that well-differentiated T cells with mature phenotypes such as HUT-78 and HUT-102 which may be considered as tumor counterparts are also capable of expressing Thy-1, presumably after certain stimulation.