Age-related alterations of the blood-brain-barrier (bbb) permeability to protein molecules of different size.

Transfer processes of differently sized protein molecules across the blood-brain-barrier (bbb) were studied in "normal" , respectively, diseased elderly humans. Lumbar CSF/serum ratio of albumin contents increased significantly with age in a control group, but it was diminished in patients suffering from inflammatory or non-inflammatory diseases. Ratio of alpha 2-macroglobulin contents increased with age, especially in the diseased elderly. Concentration ratios of lysozyme, orosomucoid, lactoferrin, IgG, IgA and IgM decreased with age in a control group and especially decreased in a patient group. The data are discussed with respect to two different transfer processes which appeared to be altered in age and/or disease processes.