Isolation, culture and main characteristics of mouse fat-storing cells: interaction with viruses

Fat-storing cells were isolated from 15-day-old mouse sinusoidal cell cultures (Kupffer or endothelial cells), where they had multiplied abundantly; they were then purified by a negative selection method based on the fact that they do not possess Fc receptors, as do both other types of cells. The fat-storing cells, which could be subcultured for at least 10 passages, have the main morphological characteristics already described in vivo, in particular, the rough endoplasmic reticulum and the lipid droplets, which become less and less apparent as the number of passages increases. Subcultured fat-storing cells, almost devoid of lipid droplets and vitamin A, were able to take up retinol, as the appearance of a typical autofluorescence indicated; the number of lipid droplets increased concomitantly. Furthermore, the cultured fat-storing cells were able to internalize one-micron-sized latex beads by phagocytosis. Infection of fat-storing cells with mouse hepatitis virus 3, ectromelia or Sindbis virus led to multiplication of the virus particles. There was a direct relation between the multiplication of mouse hepatitis virus 3 in cultured fat-storing cells and the susceptibility of the animals to the virus. In the case of Sindbis virus, interferon is produced, its production being independent of the presence of vitamin A.