Expression and Regulation of an Interferon-α-Inducible Membrane Protein p106 on Human Hematopoietic Cells

Abstract

pl06 is a human membrane protein of 106 kD previously shown to be inducible by interferon-α (IFN-α) on Daudi cells. To investigate the role of p106 further, its distribution and inducibility within hematopoietic cells was studied. Multiparameter flow cytometry (FCM) analysis showed that pl06 expression was restricted to B cells and monocytes, and in both cell lineages acquired at a late stage of differentiation. Thus, p1 06 was found on mature B lymphocytes and monocytes in peripheral blood and on a variety of freshly isolated leukemic cells of B and myeloid origin as well as on a variety of cultured B-cell lines. In contrast, no expression was found on T lymphocytes, natural killer (NK) cells or granulocytes. pl06 expression could be further induced by IFN-α on monocytes and Daudi cells, and this capacity was shown to be selective for IFN-α, since no other cytokines tested induced p106. Moreover, IFN-α therapy of chronic myeloid leukemia (CML) and hairy cell leukemia (HCL) patients lead to a clearcut induction of pl06 on such malignant cells. The distribution of p 106 could suggest that it represents an activation antigen. Further studies, including cloning of p106 cDNA, are needed to determine the function of p106.