Propagation of large numbers of cells of a human mixed-lineage T-lymphoid/myeloid

Previously, a subset of T cells co-expressing the myeloid antigen CD33 has been described in patients with acute myelogenous leukaemia. However, normal lymphocytes have been viewed as not expressing the CD33 antigen. We have developed culture conditions which allow for the rapid expansion of CD3 + CD33 + cells from patients with myeloid leukaemia as well as normal individuals. The protocol for cellular expansion includes the addition of interferon-gamma on day 0, interleukin-1. interleukin-2 and a monoclonal antibody against CD3 on day 1 to peripheral blood lymphocytes. Using this protocol. total cell number increased more than 600-fold within 16d of culture. Cells could be kept in culture for more than 6 months. Cells of the CD3 + CD33 + phenotype increased to 15.2 ± 4.6% using this protocol after 16 d in culture. These cells have been characterized by flow cytometry and have been found to express the alpha, beta T-cell receptor, coexpress the CD2, CD5, CD7 and HLA-DR antigens and did not express CD14 or CD15 antigens. Cells of the CD3 + CD33 + phenotype were unable to lyse tumour cells as determined in a 51 cr release assay. In patients with chronic myeloid leukaemia, CD3 + CD33 + cells seem to be negative for expression of bcr/abl transcript in contrast to CD33 - cells. Our data suggest that CD3 + CD33 + cells do exist in peripheral blood from normal individuals.