Demonstration of antigen excess effect. Immunofixation shows antigen excess effect (central clearing of the immunoprecipitation) in lane 3, where the patient’s serum was diluted only 1:5 prior to application to the gel and reacted with anti-λ (L). In lane 6, the patient’s serum was diluted 1:20 and reacted with the same reagent; no antigen excess effect is seen.