title: Fibrin coating of bladder tumor cells (T24) is not protective against LAK cell cytotoxicity.
abstract: Certain evidence indicates that tumor cells in the circulation may be enshrouded with a coat of fibrin. It has been suggested that this fibrin coat protects tumor cells from attack by the immune system. This study compared the interaction of lymphokine activated killer (LAK) cells with tumor cells alone and with fibrin coating. LAK cell killing of cultured human bladder tumor cells (T24) was measured by a 4-hour chromium release assay. Tumor cells (3 x 10(6] were incubated with Na51CrO4 for 2 hours at 37 degrees C and 5% CO2 in serum-free medium. After washing, one half of the cells were coated with fibrin by exposure to recalcified platelet-poor plasma. Fibrin coating was confirmed by immunofluorescence with anti-human-fibrinogen-fluorescein-conjugated antibodies. LAK cells were prepared from peripheral blood lymphocytes by incubation with interleukin-2 at a concentration of 1000 units of interleukin-2/1 ml serum-free medium/1 million cells for 5 days at 37 degrees C, 5% CO2. Five thousand tumor cells with or without fibrin were incubated with varying concentrations of either LAK or peripheral blood lymphocytes (10,000 to 100,000 cells). After 4 hours the supernatants were harvested and counted in a gamma counter for 1 minute. Over a range of effector-to-target cell ratios of 10:1 to 100:1 (LAK to T24), no difference was seen in percentage of specific lysis for T24 alone versus fibrin-coated T24 cells. At a ratio of 100:1 (LAK to T24), percentage of specific lysis was 83.3% versus 87.7% for uncoated and coated T24 cells, respectively. This suggests that fibrin coating of tumor cells is insufficient to provide protection from LAK cell killing.
authors.affiliation: Department of Medicine, Medical College of Virginia, Richmond.
authors.forename: M E
authors.initials: ME
authors.lastname: Carr
authors.forename: S A
authors.initials: SA
authors.lastname: Sajer
authors.forename: A
authors.initials: A
authors.lastname: Spaulding
mesh_terms: D003602:Cytotoxicity, Immunologic / Q000502:physiology*; D005337:Fibrin / Q000032:analysis*; D005455:Fluorescent Antibody Technique; D006801:Humans; D007376:Interleukin-2 / Q000494:pharmacology; D015979:Killer Cells, Lymphokine-Activated / Q000502:physiology*; D008214:Lymphocytes / Q000737:chemistry / Q000166:cytology / Q000473:pathology; D013997:Time Factors; D014407:Tumor Cells, Cultured / Q000737:chemistry / Q000473:pathology; D001749:Urinary Bladder Neoplasms / Q000737:chemistry* / Q000473:pathology* / Q000503:physiopathology
chemical_list: D007376:Interleukin-2; D005337:Fibrin