Exploiting CD38-mediated endocytosis for immunoliposome internalization.
CD38 appears to be a promising candidate in antibody therapy; it is upregulated on cell surfaces in many lymphoid tumors and undergoes rapid internalization after interaction with antibodies. The receptor-mediated endocytosis allows conjugating toxins/drugs that promote suicide only of the malignant cells. Here, we describe the preparation of CD38-immunoliposomes and test their functionality by incubating them with CD38+/- cells. Liposomes were prepared by extrusion of a lipid mixture containing a biotinylated polyethylene glycol-phospholipid and loaded with 5(6)-carboxyfluorescein. The anti-CD38 antibody (IB4) was biotinylated and then linked to streptavidin molecules; streptavidin acts like a bridge between the antibody and the biotinylated lipid of the liposomes. CD38+/- cells were incubated either with liposomes or immunoliposomes and analyzed by fluorescence microscopy and cytofluorimetry. The results indicated a specific mechanism of internalization, owing to CD38-mediated endocytosis, where CD38+ cells incubated with immunoliposomes scored top fluorescence levels. This coupling strategy, based on the use of a streptavidin bridge to prepare immunoliposomes, does not interfere with the cellular functionality and its broad potential use represents a great advantage. Here IB4, a murine monoclonal anti-CD38 antibody, was used to simplify the experiments, but the coupling procedure may be suitable also with human antibodies, against CD38 or other human markers.
Department of Molecular Pathology and Innovative Therapies, Histology Section, Marche Polytechnic University, Ancona, Italy.
Monia
M
Orciani
Guido
G
Cavaletti
Vincenzo
V
Fino
Monica
M
Mattioli-Belmonte
Giovanni
G
Tredici
Paolo
P
Bruni
Roberto
R
Di Primio
D051997:ADP-ribosyl Cyclase 1 / Q000502:physiology*; D000911:Antibodies, Monoclonal / Q000008:administration & dosage*; D019921:Biotinylation; D004705:Endocytosis; D006801:Humans; D020014:K562 Cells; D008081:Liposomes / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000502:physiology*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D000911:Antibodies, Monoclonal; D008081:Liposomes; D008562:Membrane Glycoproteins; C498154:CD38 protein, human; D051997:ADP-ribosyl Cyclase 1; D013755:Tetradecanoylphorbol Acetate