Membrane proteins stimulated by interferon-alpha in growth-inhibited, but not in resistant, Daudi cells

Interferon-alpha (alpha-IFN) stimulates the expression of a number of plasma membrane proteins in wild-type Daudi cells. These proteins are not induced in a variant subline of Daudi cells, which is insensitive to growth inhibition, nor in another which is partially growth-inhibited by alpha-IFN. Two-dimensional polyacrylamide gel electrophoresis of [125I]-surface labelled Daudi membrane proteins indicates that the major protein induced de novo has a molecular weight of 16 kD (p16), and proteins of 20 kD (p20), 28 kD (p28) and 106 kD (p106) which are present in untreated cells are also induced by alpha-IFN. A monoclonal antibody was produced against p106 by immunizing mice with cells treated for 16 h with alpha-IFN followed by differential screening against treated and untreated cells. The antibody (A96/G8) immunoprecipitated p106 from cell lysates and was used to show that p106 is induced approximately two-fold by alpha-IFN in wild-type Daudi cells, but not at all in Daudi cells which show a complete or partial resistance to growth inhibition by alpha-IFN; gamma-IFN does not induce p16 or p106 and also does not inhibit cell growth. The induction of p16 and p106 precedes the observed inhibition of growth by IFN. The levels of p16 and p106 are elevated by 8.5 h and in the case of p16 continue to rise for 16 h after the addition of IFN, whereas p106 reaches a peak by 8.5 h. In contrast, growth inhibition is not observed by 8 h and does not become clear-cut until 24 h after the addition of IFN.