Persistence of Circulating Antibodies in Human Subjects Immunized with Dextran, Levan and Blood Group Substances

Summary Persistence of circulating precipitins to blood group A substance, dextran and levan, were followed in a small number of individuals over a period of years. Despite the presence of amino acids in blood group A substance, anti-A showed a persistence pattern comparable to pneumococcal anticarbohydrate, antidextran and antilevan. Three anti-A sera and 2 antidextran sera showed a decline in antibody level from ⅓ to ⅔ peak values over a period of about 3 years, with the subsequent maintenance of these levels of circulating antibody N for a period of 1 to 9 years.