THE LECTIN JACALIN SPECIFICALLY TRIGGERS CELL SIGNALING IN CD4(-LYMPHOCYTES() T)

The lectin jacalin was shown to specifically stimulate CD4(+) lymphocy tes, This lectin, which presents a peptide highly similar to a sequenc e of the HIV external glycoprotein, interacts with CD4 and is able to inhibit in vitro HIV infection, Since jacalin binds also CD8, its mito genic specificity cannot exclusively be attributed to its interaction with CD4. We therefore hypothesized that the lectin could trigger sign als speci fically associated with CD4, Here we show that jacalin trigg ers IL2 gene transcription only in CD4(+) lymphocytes, In parallel, we show that numerous proteins are tyrosine phosphorylated in this cell subset while only a restricted number of them are phosphorylated in CD 8(+) cells, Moreover, we show that the tyrosine kinase p56(lch), which is associated with both CD4 and CD8, is activated only in CD4(+) lymp hocytes, making this lectin a good model for the study of cell signali ng triggered in this restricted subpopulation. (C) 1997 Academic Press .