Expression of Lyp proteins in resting and activated T cells. (A) Lyp was precipitated from thymocytes (80 × 10⁶cells), peripheral blood T cells (25 × 10⁶ cells), and tonsil T cells (10 × 10⁶ cells) and immunoblotted with anti-Lyp. Preimmune serum controls (PB) are presented in each case. A band of 105 kD is present in each sample and a band of 85 kD can be seen only in resting peripheral T cells. (B) Lyp was immunoprecipitated from peripheral blood T cells (25 × 10⁶ cells) before and after stimulation with anti-CD3 (2.5 μg/mL) or PHA over a period of 48 hours. There is increased 105-kD Lyp1 expresssion, whereas the 85-kD protein appears to be downregulated.