Effects of two international union against cancer standard reference samples of asbestos on cultured rabbit ovarian surface epithelial cells.

To evaluate their interaction with asbestos, rabbit ovarian surface epithelial cells were exposed in vitro to amosite or Rhodesian chrysotile fibers (5.0 micrograms/ml). The morphology of these cells was studied by phase-contrast, scanning and transmission electron microscopy. Amosite fibers up to 10 micron in length were phagocytized by surface cells within 24 hours. Internalization of amosite fibers occurred prevalently over microvilli-rich regions of the cell surface and, after 4 days, the intracytoplasmic localization of these fibers was most often perinuclear. In contrast with amosite, chrysotile fibers were less frequently phagocytized. Instead, they caused focal cell membrane damage, intracytoplasmic vacuolization and cell clumping. A different effect of the two asbestos fibers was also observed when estimates of cell growth were obtained in replicate cultures exposed to fibers before cell confluence. In contrast with asbestos-free cultures which underwent a 4.3 fold increase in cell number, cells exposed to amosite displayed nearly a 7-fold numerical increase (ca. 160% of controls; P less than 0.05). Cells maintained in presence of chrysotile grew 3.5 fold (approximately 80% of controls). When administered at the time of cell plating, both mineral fibers (chrysotile greater than amosite) significantly depressed cell growth. These data indicate that amosite and chrysotile asbestos can have cytotoxic or proliferative effects on ovarian surface epithelial cells. Further investigation is required to ascertain if susceptibility of these cells to mineral fiber injury may play a role in the genesis of proliferative ovarian surface lesions.