Recognition and elimination of senescent erythrocytes: implication of antibodies specific for malonic dialdehyde-protein adducts, as demonstrated by flow cytometry.

Many different hypotheses have been formulated about the mechanisms of specific recognition of senescent red blood cells (RBC). It is usually assumed that novel epitopes appear on RBC membranes during ageing and are responsible for recognition of aged RBC by antibodies, which is followed by binding to mononuclear phagocytes and then phagocytosis. But these age-related epitopes have not so far been identified. Lipoperoxidation is known to produce aldehydes, among which malonic dialdehyde (MDA). This dialdehyde reacts with primary amino groups of biological molecules, producing 1-amino-3-imino propene (AIP) bridges, and we had previously shown that sera of healthy mammals contain antibodies recognizing epitopes containing AIP bridges (AbAIP). Lipoperoxidation is responsible for many age-related damages in RBC membrane, and we tried in the present work to determine whether age-related epitopes responsible for recognition of aged RBC were not derived from lipoperoxidation. Using flow cytometry techniques, we demonstrated that some of the epitopes recognized by immunoglobulins which bind to aged RBC contain AIP bridges, and that some of these RBC-bound immunoglobulins are AbAIP. Consequently, AbAIP/AIP bridges interactions appear to play a role in recognition and elimination of senescent RBC.