From where do A, B, and RH anti-bodies come?
By the age of three months, human infants acquire blood group
antibodies that will attack non-self blood types. The origin of these
antibodies is a mystery. One hypothesis is that bacteria enter the blood
stream in teething infants, and antigens on the bacteria stimulate the
production of antibodies which are also specific to blood type antigens.
Somehow, the body's thymus gland prevents the formation of
anti-bacteria antibodies that would attack the body's own blood
type. If this hypothesis is true, then anti-sera consisting of
monocional antibodies to blood type antigens should also react with at
least some of the bacteria usually present in the mouth. In this
experiment, broth suspensions of various oral bacteria were treated with
commercial anti-sera looking to see if the anti-sera triggered
agglutination of the bacterial cells through antibody binding. While the
microscopic observations were somewhat subjective, it was found that the
anti-sera agglutinated some oral bacteria but not others, an
observations which is consistent with the hypothesis that oral bacterial
antigens are responsible for blood group antibodies.
Amelia Dickerson, Cherry Creek High School.