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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.
Allen et al. (1958) studied this question.