Accumulation of p60^lck in HTLV‐I‐transformed T Cell Lines Detected by an Anti‐Lck Monoclonal Antibody, MOL 171

The lck gene encodes a protein tyrosine kinase of nonreceptor type, p56^lck, whose expression occurs almost exclusively in T lymphocytes. MOL 171, an anti‐p56^lck monoclonal antibody, was produced by using a 25‐amino‐acid synthetic polypeptide as the antigen, its structure corresponding to the N‐terminal region deduced from the lck cDNA sequence. Immunoblot analysis with MOL 171 showed the accumulation of 60 kD form of Lck protein, p60^lck, and the decrease of p56^lck in human T cell leukemia virus type I (HTLV‐I)‐transformed T cell lines. Another anti‐Lck monoclonal antibody, MOL 294, raised by using a synthetic peptide corresponding to the C‐terminal region deduced from the lck cDNA sequence, also detected the accumulation of p60^lck in those HTLV‐1‐transformed T cell lines. The appearance of p60^lck with the decrease of p56^lck in normal T lymphocytes after stimulation suggested the origin of p60^lck in HTLV‐I‐transformed T cells.