INDUCTION OF GENE-EXPRESSION OF AMYLOID PRECURSOR PROTEIN (APP) IN ACTIVATED HUMAN LYMPHOBLASTOID-CELLS AND LYMPHOCYTES

To understand the possible role of amyloid precursor protein (APP) in human lymphocytes, and the regulation of APP gene expression in this c ell type, we determined levels of cellular APP protein and of mRNA in human T-cell-derived Jurkat cells that were treated with lectin, phorb ol ester, and calcium ionophore. We also related these levels to cell aggregation and adhesion. Cell-cell aggregation and cell-plastic adhes ion were observed over a 24-h period after incubating cells for 2 h wi th phytohemagglutinin or phorbol myristate acetate. Cells treated with a calcium ionophore showed no aggregation or adhesion. Western blots indicated no obvious alteration in the level of cellular APP with diff erent treatments. Northern blots showed a significant transient increa se of APP mRNA after incubation with the calcium ionophore, whereas ph orbol ester treatment showed a slight increase of APP mRNA. We analyze d the level of APP mRNA in human peripheral T cells which had been sep arated from peripheral lymphocytes. The level increased transiently by up to threefold after treatment with calcium ionophore plus phorbol e sters. These data suggest that cell-cell aggregation and cell-matrix a dhesion by human lymphocytes are not associated with an increased leve l of cellular APP protein or of mRNA.