Induction of the tyrosine phosphorylation of a 66 KD soluble protein by DMSO in human peripheral blood T lymphocytes

Previous studies from our laboratory have demonstrated that a 66 KD cytoplasmic protein (TPP 66) is newly phosphorylated on tyrosine when human peripheral blood T lymphocytes are incubated with a variety of agents that activate these cells or augment activation by known mitogens. Since DMSO has been shown to activate tyrosine specific protein kinases we have examined the role of this agent on the phosphorylation of TPP 66. 5 to 40% DMSO induced the phosphorylation of TPP 66 with the maximal increase in phosphorylation seen at 20%. Concentrations greater than 40% were inhibitory. Phosphorylation of TPP 66 in DMSO treated cells could be detected as early as 2 min following the addition of DMSO, with increased [³²P]O₄ incorporation over the next 60 min. The phosphorylation was on tyrosine residues demonstrated by base hydrolysis of TPP 66 extracted from the gels followed by single dimension high voltage electrophoresis. Since DMSO augments activation of T lymphocytes by lectins, this data provides further support for a critical role for the tyrosine phosphorylation of TPP 66 in the mediation of modulation of T lymphocyte activation.