Antigenic changes in the developing brain of the hamster

Abstract The appearance and subsequent disappearance of certain brain antigens were followed through several stages of early mammalian development. Antiserum against 5-day postnatal, premyelinated hamster brain was reacted in micro gel-diffusion plates with homogenates of whole brain from 11- and 14-day fetal, newborn, 3-, 5-, 7-, and 15-day postnatal and adult hamsters. Precipitin line specificity was tested by the method of Bjorklund (3). Three distinctive precipitin lines were selected for study. One, containing antigen specific to brain, was present in reactions involving all the ages studied. Another, also containing brain-specific antigen, was present in reactions involving fetal and all postnatal ages except that of the adult. The third line, containing non-brain-specific antigen, was present in reactions involving 14-day fetal and all postnatal ages except that of the adult. The antigenic components identified with this third line were located increasingly nearer the antigen wells in reaction with progressively older brain. These components also varied in position depending on their source, as observed when different subdivisions of 5-day postnatal brain were reacted against the antiserum. Limited tests with repetitively frozen and thawed brain suggest that some antigenic determinants, otherwise thought to disappear with age, may be residually retained in adult brain. These observations, along with those of others, indicate a significant time relationship between the period of myelination and changes involving a number of antigens in developing vertebrate brain.