Observations on different origins of “naturally” occurring antibodies

In 6 weeks old C57BL/10J mice specificities of “naturally” occurring antibodies to determinants of the widely distributed ABH‐(blood group)system are highly sex‐dependent. This is not reflected by ABH‐antigenic differences of red cells and tissues. The response of C57BL/10J mice to known heterologous AB antigens might show that production of certain “naturally” occurring hemagglutinating antibodies cannot be induced by exogenous heterologous antigens. With regard to the rare linkage of C57BL/10J mice hemagglutinins to XX and XY chromosome sets, and taking into account the peculiar occurrence of hemagglutinins in germ cells of certain animals and plants, it is assumed that growth and maturation mechanisms might have a relation to hemagglutinin production.