The dilution endpoint refers to the maximum degree of dilution that can be achieved for an antiserum without compromising its ability to bind to the corresponding antigen that was utilized in its creation. This critical point is typically determined by performing an antigen-antibody assay, in which the antiserum is tested against the same antigen that was used in its production. The dilution endpoint is established when the antiserum can no longer bind to the antigen in a detectable manner.