Correlation of Leukemia-associated Antigens and Ph Chromosome in Fibroblastlike Cells Derived From Bone Marrow

Abstract

A search was made for the Philadelphia chromosome (Ph 1 +) and leukemia-associated antigens (LAA) in fibroblastlike cells (FLC) derived from human bone marrow. A variable number of Ph 1 + cells were observed in seven primary cultures and five monolayer passages of FLC derived from patients with chronic myelogenous leukemia. Three monolayers of FLC from normal bone marrow and three cultures of skin fibroblasts were used as controls. LAA were determined by (1) the antibody-dependent, complement-mediated cytotoxicity assay using a monkey antiserum made to the Ph 1 +cell line, K-562, and (2) the immunoperoxidase assay using the monkey antiserum and rabbit anti-monkey IgG fraction conjugated with peroxidase. By these criteria, Ph 1 + FLC were positive for LAA while Ph 1 - FLC were negative. Linear regression analysis indicated that there was a direct correlation between the number (3%-18%) of the Ph 1 + FLC and the number (12%-30%) of immunoperoxidase-positive cells in the same cultures (r = 0.635) and also between the latter and the amount (18%-66%) of “Cr released per 106 cells (r = 0.834). The data presented herein show that Ph 1 + FLC possess LAA similar or identical with that found in highly undifferentiated myelogenous leukemia cells. This suggests that the Ph 1 + FLC may represent the earliest precursor (stem cell?) pool of myelogenous leukemia or stromal cells. The Ph 1 + FLC bearing LAA detached from the solid surface, which was overgrown by normal FLC that depended on anchorage for growth. Thus leukemic FLC did not survive well in long-term monolayer cultures.