Phenotypic and genotypic analysis of Hodgkin's disease derived cell lines: histopathological and clinical implications

Abstract

Five Hodgkin's disease (HD) derived cell lines were established in vitro in our laboratory in the last seven years. Morphological, cytochemical, immunological and cytogenetic marker analysis demonstrated that the in vitro cells represent genotypically and phenotypically the in vivo Hodgkin (H) and Sternberg-Reed (SR) cells in biopsy specimens. The cultured cells resemble haematolymphoid cells at different stages of maturation. Four of the five continue to grow in vitro as suspension cells after more than 50 months. Four more in vitro HD-derived lines were described recently by several authors. A summary of the various marker characteristics of these in vitro lines is given as a synopsis of the phenotypic marker spectrum and is discussed in comparison with our own cell lines. There is a striking similarity between two of the newly established lines (CO, HDLM-2) and our lines whereas the two other in vitro established cultures seem to resemble cell species further along the line of maturation to B lymphocytes (DEV) and monocytes (SU-HD-1). Gene rearrangement experiments undertaken with the L428, L540, L591 and the CO cell line show that the L428 and 591 cells have undergone gene rearrangement, the L428 being compatible with the genotypic state of a pre-B cell; the L591 cells, similarly rearranged furthermore demonstrated functional light chain rearrangement, compatible with B-cell development. By cytogenetic analysis chromosome 7 was found to be affected in all our described lines. This chromosome appears to be particularly unstable and vulnerable in patients with HD, since all tested cell lines revealed multiple abnormalities of this chromosome, a finding which is in accordance with observations made by other investigators in HD-biopsy cells. Since similar structural changes or loss of chromosome 7 is a characteristic event in cases of secondary acute non-lymphocytic leukaemia, it is speculated that this form of secondary neoplasia could resemble the blast crisis, as observed in chronic myeloid leukaemia.