Antigen binding of a mouse monoclonal IgG1 is inactivated by heating but not by freeze/thaw cycling.

A mouse monoclonal antibody in ascitic fluid or in purified form was subjected to heating or repeated freeze/thaw cycles. Heating the antibody at 80 degrees C for 10 min completely destroyed its ability to bind to antigen. Unpurified antibody in ascitic fluid or purified antibody in buffer was frozen to -196 degrees C in liquid nitrogen and then thawed at room temperature. Purified antibody was also slowly frozen at -4 degrees C followed by thawing at room temperature. Regardless of the manner of freeze/thaw treatment or whether the antibody was purified or not, immunologic competence for its antigen was not lost. The results call into question the belief that freezing and thawing in all cases are necessarily deleterious to antibody structure and function.