Effects of development and aging on the concentration of a human brain antigen.

The concentration of a glycoprotein reactive with monoclonal antibody 44D10 was studied during development and aging in 19 normal brains. Little change in the concentration of the antigen was found in white matter of brains ranging from the age of 1 to 54 years. However, a linear increase in the concentration of antigen was observed between the ages of 54 and 80 years. By the age of 80 years, the concentration of the glycoprotein had increased 2-3-fold. In contrast to white matter, gray matter did not contain detectable levels of antigen at ages from 1 to 54 years. Low levels of antigen were detected in brains of all older individuals examined. However, the relative concentration of this glycoprotein in gray matter was less than 5% of that in white matter. An examination of white matter homogenates from guinea pig and bovine brain showed that monoclonal antibody 44D10 was not reactive in these species.