HETEROLOGOUS REACTIONS OF MAMMALIAN SERA WITH MONOSPECIFIC ANTI-HUMAN-SERA A CONTRIBUTION TO EVOLUTION OF SERUM PROTEINS .2. INVESTIGATIONS ON PREALBUMIN BETA2-GLYCOPROTEIN ACID ALPHA1-GLYCOPROTEIN ALPHA1-TRYPSIN INHIBITOR

In continuation of earlier investigations the reactions of monospecific antisera against human prealbumin, β2-glycoprotein, acid α1-glycoprotein and α1-trypsin inhibitor were tested with a series of animal sera to investigate the evolution of these serum proteins. We found the sera of the following species reacting, when using the micro-modification of the Ouchterlony-technique: For prealbumin: rhesus and mangabe monkeys and cattle; for β2-glycoprotein: cattle, sheep, pig, guinea pig, and rat (monkey sera were not tested); for acid α1-glycoprotein: rhesus and mangabe monkeys; for α1-trypsin inhibitor: no reaction (monkey sera were not tested). From the cross-reactions the minimum number of antigenic determinants of human prealbumin was determined as 2, the one of human β2-glycoprotein as 4. Monkey sera are not included in these results. The 20 plasma proteins investigated by us so far can be classified into three groups: Group I shows 3- with the exception of the chimpanzee 3- no cross-reactions at all, group II only with primate sera. For group III immunological relationship can further be found with other mammalia. Sera from fowl and eel, representing birds and fishes, did not react. Factors responsible for these differences in cross-reaction are discussed in greater detail: a) Molecular weight, carbon hydrate content, IEP resp. electrophoretical mobility are not related to the persistence of phylogenetically old determinants. b) An influence of the concentration of the proteins could not be excluded. c) In some cases a parallelism between the persistence of phylogenetically old determinants and ontogenetically early synthesis for a given protein may be possible, when one takes account of the data compiled in the literature on the ontogenetically different beginning of synthesis of the different plasma proteins. The quotient of the number of plasma proteins, demonstrable in fetal blood (without IgG, which is known to be transported through the placenta) to their total number rises from 0.00 for group I to 0.33 for group II and to 0.64 for group III. This finding is in accordance with a hypothesis put forward by Goodman, that the formation of the hemochorial placenta may lead to an immunization of a mother against mutated proteins of a fetus if these are synthesized early in fetal life. Such an immunization being dangerous for the fetus might well be responsible at least in part for the ontogenetical-phylogenetical parallelism mentioned. The finding is also a special case of our concept introduced earlier, that mutations of serum proteins leading to a change of the older immunological structure of a protein are limited by the disadvantages for selection they lead to. © 1969 Springer-Verlag.