The Formation of Macroglobulin Antibodies. I. Studies on Adult Humans*

The occurrence of antibodies of different molec-ular size in man and experimental animals has long been known (1). In recent years increasing attention has been focused on the group with high molecular weight (19S), which includes not only a number of well defined antibodies but, in addi-tion, certain substances with similar electropho-retic and ultracentrifugal characteristics that are not firmly established as antibodies. Both groups have been discussed by Kunkel, Fudenberg and Ovary (2, 3). Although numerous immunoglobulins in human serum are found either in the 7S or 19S class of y-globulins, certain antibody activities are found in both classes. Among these are the isoagglu-tinins (3), Wassermann antibodies (4), and lupus factors (5). In addition, antibodies to typhoid H antigen have recently been found in both the 7S and the 19S fractions in the sera of neonatal infants and adults (6, 7). In the course of an investigation of the immune response to typhoid and paratyphoid antigens (8) in patients with a variety of diseases, it was ob-served that the individuals tested could be placed in one of three categories with respect to the size of the antibodies produced. One group produced only the 7S type; a second, only the 19S type; and a third, a mixture of the two. This distribu-tion is similar to that found for saline anti-A isoagglutinins in different individuals (3). This studv was undertaken to elucidate the factors governing the formation of one or the other type of antibody and the interrelationship, if any, of the two types.