Intercellular adhesion induced by anti-alpha 3 integrin (VLA-3) antibodies.

We generated four monoclonal antibodies (mAbs) specific for human alpha 3 integrin (VLA-3 alpha subunit). All of them were found to induce homotypic cell aggregation of HT1080 fibrosarcoma and SN12C renal carcinoma cells, both of which express high levels of alpha 3 integrin. The antibodies also induced the cell aggregation of K562 erythroleukemic cells transfected with alpha 3 integrin cDNA, but not the parental K562 cells. The aggregation was observed in a temperature-dependent manner and was not inhibited by the addition of EDTA. Immunofluorescence microscopic observation showed that alpha 3 integrin on HT1080 cells was translocated into the contact regions after the mAb treatment. The intercellular adhesion between cells expressing alpha 3 integrin and cells without alpha 3 integrin was also induced by the anti-alpha 3 antibody treatment.