Target-cell specificity of fusogenic liposomes: Membrane fusion-mediated macromolecule delivery into human blood mononuclear cells

Fusogenic liposome, a unique vector prepared by fusing ultraviolet-inactivated Sendai virus and liposome, is known to efficiently deliver content into various animal cells through membrane fusion. In this study, we examined the target-cell specificity of fusogenic liposome (FL)-mediated macromolecule delivery into human blood cells using diphtheria toxin fragment A (DTA) as a probe. Among the peripheral blood mononuclear cells (PBMC), FL was able to deliver its encapsulates into CD14(+) monocytes and CD4(-)/CD8(-) T-cells, but not into CD19(+) B-lymphocytes, CD4(+) T-cells or CD8(+) T-cells. The susceptibility of human leukemia cell lines to FL was similar to that of PBMC; the order of the reactivity was U937 (monoblastic leukemia)> MOLT4, Jurkat (T-lymphoma)> Daudi, BALL1 (B-lymphoma) > K562 (erythroblastic leukemia). Interestingly, FL showed similar binding activity to all of these leukemia cell lines. These findings indicate that, among blood cells, monocytes, monoblastic leukemia cells, CD4(-)/CD8(-) T-cells and T-lymphoma cells are preferable targets for FL-mediated macromolecule delivery. This is the first demonstration of the existence of non-permissive cells against FL. Our results also suggest that some molecules on target-cells other than the binding targets of SV-derived protein may participate in fusion between FL and cells. (C) 1999 Elsevier Science B.V. All rights reserved.