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.
Orciani
Monia
M
Department of Molecular Pathology and Innovative Therapies, Histology Section, Marche Polytechnic University, Ancona, Italy.
Cavaletti
Guido
G
Fino
Vincenzo
V
Mattioli-Belmonte
Monica
M
Tredici
Giovanni
G
Bruni
Paolo
P
Di Primio
Roberto
R
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