Micro-scission of YAC tumor cells during antibody-dependent cellular cytotoxicity mediated by human neutrophils.
The cellular events accompanying neutrophil-mediated antibody-dependent cellular cytotoxicity (ADCC) directed against YAC erythroleukemic target cells have been studied by time-lapse fluorescence-intensified microscopy. The YAC plasma membrane and cytosol were labeled with the fluorescent probes diC18Icc and eosin Y, respectively. Fluorescently labeled and IgG-opsonized YAC cells were incubated at 37 degrees C while observed by optical microscopy. During temporal studies of neutrophil-YAC conjugates, the cytosol of YAC cells accumulated in tubular and spherical compartments of the neutrophils' vacuolar apparatuses. To distinguish between several possible mechanisms of target cytosol uptake, diC18Icc-labeled YAC cells were observed during identical conditions. The membrane label diC18Icc was found to accumulate within neutrophils in an identical fashion. At roughly 30 min, 25 and 38% of neutrophils in apparent conjugates had internalized tumor cell cytosol or plasma membrane, respectively, within a vesicular compartment. The IgG-dependent uptake of eosin Y and diC18Icc by neutrophils was diminished by exposure to 2.5 mM sodium azide. When cells were exposed to 5.5 mM sodium azide, 1 mM iodoacetamide, or 4 degrees C, conjugate formation and uptake of eosin Y or diC18Icc were abolished. An artifactual accumulation of eosin Y or diC18Icc in neutrophils was further ruled out by control studies. Non-specific exchanges of eosin Y and diC18Icc labels of YAC cells with tannic acid-treated red blood cells (RBCs) and normal neutrophils were studied. Since hemoglobin binds tightly to eosin Y, RBCs can easily detect eosin Y leakage. No exchange of eosin Y or diC18Icc from YAC cells into bound tannic acid-treated erythrocytes was found.(ABSTRACT TRUNCATED AT 250 WORDS)
Zhou
M
M
Department of Biological Sciences, Wayne State University, Detroit, MI 48202.
Petty
H R
HR
D000920:Antibody-Dependent Cell Cytotoxicity; D004705:Endocytosis; D004801:Eosine Yellowish-(YS); D004912:Erythrocytes / Q000378:metabolism; D006801:Humans; D047348:Hydrolyzable Tannins / Q000494:pharmacology; D007074:Immunoglobulin G; D008856:Microscopy, Fluorescence; D009504:Neutrophils / Q000276:immunology*; D013050:Spectrometry, Fluorescence; D014407:Tumor Cells, Cultured
D047348:Hydrolyzable Tannins; D007074:Immunoglobulin G; D004801:Eosine Yellowish-(YS)