Immunospecific vesicle targeting facilitates microinjection into lymphocytes.

Antibody-directed targeting of vesicles to cells dramatically enhances polyethylene glycol-mediated fusion and microinjection. Sealed erythrocyte ghosts, containing fluorescent bovine serum albumin, were targeted to murine spleen and thymus cells, and to lymphocyte, monocyte, and fibroblast cell lines. In all cases, targeted cell populations showed substantial levels of microinjection, whereas populations treated with the fusogen in the absence of targeting were not significantly microinjected. To achieve attachment of vesicles to selected cells, the cells were first labeled with biotin-modified antibody then treated with sealed ghosts prepared from avidin-coupled erythrocytes. This procedure should prove useful when the injection of specific cell populations is desired, or with cell types such as lymphocytes that are difficult to fuse, or when the use of limited reagents necessitates high injection efficiencies.