Improvement by affinity chromatography on antiidiotypic monoclonal antibodies (MAbs) of immunoreactivity and in vivo targeting of radiolabelled anti-HMW-MAA MAb TP61.5 in nude mice bearing human melanoma lesions.
The human high-molecular-weight melanoma-associated antigen (HMW-MAA) represents a useful marker for immunoscintigraphy in patients with melanoma. Since injection of a radiolabelled anti-HMW-MAA monoclonal antibody (MAb) visualizes only about 60% of melanoma lesions, approaches are being developed to increase the sensitivity of immunoscintigraphy. One of them aims at improving the immunoreactivity of radiolabelled anti-HMW-MAA MAbs, since this approach may improve the targeting of radiolabelled MAbs to melanoma lesions. We have previously shown that affinity chromatography on insolubilized anti-idiotypic MAbs is a useful method for purifying immunoreactive anti-HMW-MAA MAb TP61.5 from 125I-labelled MAb preparations and that not all the anti-idiotypic MAbs are useful for this purpose. Since the increasing number of available anti-idiotypic MAbs is likely to facilitate the application of this procedure in many antigenic systems, we have now tested criteria to select anti-idiotypic MAbs suitable for the purification procedure. Furthermore, we have investigated the effect of the increase in immunoreactivity of 125I-MAb TP61.5 on its in vivo targeting to human melanoma lesions transplanted into nude mice. Among the 3 anti-idiotypic MAbs tested, the most effective in purifying immunoreactive MAb TP61.5 molecules following radiolabelling is MAb TK7-110, with which 125I-MAb TP61.5 displays an immunoreactivity similar to that displayed with melanoma cells. This parameter may represent a useful criterion to identify anti-idiotypic MAbs suitable for the purification procedure, if the present results are confirmed with a large number of anti-idiotypic MAbs in different antigenic systems. We have also shown that an incubation time for up to 4 hr of 125I-MAb TP61.5 with insolubilized MAb TK7-110 is the most effective in increasing immunoreactivity and in recovering immunoreactive MAb applied to the affinity matrix. The increase in the immunoreactive fraction of 125I-MAb TP61.5 significantly increases its specific localization in human melanoma lesions transplanted into nude mice. These results suggest that purification of radiolabelled immunoreactive anti-HMW-MAA MAb TP61.5 by affinity chromatography using anti-idiotypic MAb TK7-110 represents a useful approach to increasing the sensitivity of immunoscintigraphy in patients with melanoma.
Department of Microbiology and Immunology, New York Medical College, Valhalla 10595.
M
M
Temponi
R A
RA
Fawwaz
U
U
Kekish
T S
TS
Wang
S
S
Ferrone
D000818:Animals; D000911:Antibodies, Monoclonal / Q000302:isolation & purification* / Q000378:metabolism; D002460:Cell Line; D002846:Chromatography, Affinity / Q000379:methods; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D007130:Immunoglobulin Idiotypes / Q000276:immunology*; D007457:Iodine Radioisotopes / Q000493:pharmacokinetics; D008545:Melanoma / Q000000981:diagnostic imaging* / Q000378:metabolism; D051379:Mice; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D016719:Radioimmunodetection / Q000379:methods; D014018:Tissue Distribution; D014183:Transplantation, Heterologous
D000911:Antibodies, Monoclonal; D007130:Immunoglobulin Idiotypes; D007457:Iodine Radioisotopes