| Abstract |
A continuous adherent tumor cell line, MH1, of 5 years duration has been
established from the bone marrow of a 62-year-old man with systemic
malignant histiocytosis. The neoplastic nature of MH1 is indicated by
structural and numerical chromosome abnormalities with a clonal pattern of
marker chromosomes (including a duplicated 14q+ chromosomal abnormality),
tumor cell colony growth in soft agar, and absence of EBNA. MH1 closely
resembles tumor cells in the original bone marrow aspirate, and both have
cytochemical characteristics of histiocyte/macrophages. They contain large
amounts of alpha-naphthyl acetate esterase-inhibited by NaF and acid
phosphatase but are unstained for chloracetate esterase, myeloperoxidase,
and Sudan black B. MH1 has cytoplasmic receptors for Con-A and peanut
agglutinin and surface receptors for transferrin but lacks both
cytoplasmic and surface Ig, B, and T cell differentiation antigens, Ia and
Ki-1 antigens. Although erythrophagocytosis was found in 4% of tumor cells
in the original bone marrow aspirate, erythrophagocytosis by MH1 cells is
rare and not enhanced by treatment with phorbol ester, dimethylsulfoxide,
or supernatants from mixed lymphocyte cultures. Moreover, MH1 does not
appear to produce lysozyme or colony-stimulating factor for myeloid
progenitor cells. Based on these features, the moderate cytologic atypia,
rare phagocytosis, and absence of lysozyme, MH1 is considered to belong to
the poorly differentiated group III of malignant histiocytosis described
by Mendelsohn et al. (Cancer 45:273, 1980). MH1 may be useful to study
markers specific for early histiocyte differentiation and for the
differential diagnosis of malignant histiocytosis.
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