Expression of protein tyrosine phosphatase, non-receptor type 22 (PTPN22) isoforms in human helper T (Th) cells and macrophages. (A) RNA was prepared from human Th cells obtained from three healthy donors, which were stimulated in vitro with anti-CD3/anti-CD28 for indicated periods of time and subjected to real-time PCR analysis with isoform-specific primers. Each real-time PCR reaction was done in duplicate. The transcript levels thus obtained were normalized against those of β-actin from the same samples. The data shown are the means and standard deviations from three donors. (B) Protein extract prepared from human Th cells described in A was subjected to Western blotting and probed with PTPN22 antibody and Hsp90 antibody. (C) RNA was prepared from resting, M1, and M2 macrophages derived from peripheral blood of seven additional healthy donors and subjected to real-time PCR analysis with isoform-specific primers.