Lack of lamins A and C in mammalian hemopoietic cell lines devoid of intermediate filament proteins

Using immunofluorescence microscopy and immunoblot analysis, we have examined the composition of the nuclear lamina in several murine and human cell lines. Whereas it was shown that intermediate filament-positive Ehrlich ascites tumor and HeLa-S3 cells contain the three major mammalian lamin subspecies, only lamin B could be detected in several myeloid- and lymphoid-derived cell lines representative of distinct stages in hemopoietic differentiation but all devoid of cytoplasmic intermediate filament proteins. These included the murine plasmacytoma cell types MPC-11 and MOPC-31C, murine myeloma cells X63-Ag8.6.5.3 and human promyelocytic leukemia cells HL-60. Our results provide the first evidence that mammalian somatic cells capable of normal proliferation may lack both cytoplasmic intermediate filament proteins and a normal complement of nuclear lamins.