Immunochemical characterization of mature and immature glomerular basement membrane

20 kidneys from premature infants (27th to 38th weeks of gestation), 5 kidneys of mature newborns and 5 kidneys of children between 5 and 15 years of age were obtained at necropsy and glomerular basement membranes (GBM) isolated. The isolated GBMs were degraded by papain and the degradation products were characterized by immunoelectrophoresis applying an antihuman GBM antiserum from the rabbit. GBMs of children between 5 and 15 years showed in each case 3 precipitation lines distributed from the alpha-gamma-zone. The examined newborns and 17 premature infants presented two precipitation lines only, moving with alpha 1-mobility and beta-gamma-inter-region. 3 premature infants showed a pattern with 2--4 different precipitation lines of different mobility, maybe interpretable as a result of bacterial digestion. On the grounds of these findings we postulate that the GBM is, from an immunochemical point of view, immature at birth and in the late fetal life becoming mature in the child with about 5.