SUBARACHNOID MACROPHAGES SHARE A COMMON EPITOPE WITH RESIDENT NON-CEREBRAL MACROPHAGES AND SHOW RECEPTOR-MEDIATED ENDOCYTOSIS OF ALBUMIN-GOLD AND IGG-GOLD COMPLEXES

Cerebral macrophages are supposed to exploit a pivotal role in scavenger functions of the central nervous system. We have examined the in vivo uptake of serum albumin and IgG conjugated with colloidal gold by subarachnoidal macrophages. These serum-borne proteins are endocytosed by receptor-mediated endocytosis by varying kinetics. Albumin-gold conjugates were found to be associated to a significant amount with coated pits and coated vesicles 1 min after superfusion of the cerebral surface. Within 25 min the major fraction of albumin-gold was transferred to the lysosomal compartment. IgG-conjugates revealed a less pronounced uptake. The uptake of albumin-gold could be competed by saturating of the 'receptor sites' with free albumin. It is suggested that the described receptor-mediated uptake of serum-borne proteins by subarachnoidal macrophages serves a cleansing function following blood-brain barrier disruption during acute or subacute inflammatory reactions.