Differential induction of macrophage recognition of carrier erythrocytes by treatment with band 3 cross-linkers

Mouse native and hypotonically loaded erythrocytes were treated with two cross-linking reagents: bis(sulphosuccinimidyl)suberate (BS3)- and 3,3'-dithiobis-(sulphosuccinimidyl propionate) (DTSP), excluding clustering agents. Microscopic analyses revealed that band 3 cross-linked native and hypotonically loaded erythrocytes are more strongly recognized by peritoneal macrophages than native and loaded erythrocytes as a result of the cross-linking of band 3 protein in accordance with studies in vivo. Macrophage-recognition analyses of 51Cr-labelled erythrocytes also demonstrated increased recognition of cross-linked and cross-linked loaded erythrocytes. This shows that the only action of these two band 3 cross-linkers on mouse erythrocytes promotes recognition by macrophages without requiring the use of clustering agents. The extent of recognition of BS3 cross-linked and cross-linked loaded erythrocytes by macrophages is dependent on the presence or absence of homologous serum or immunoglobulins. In contrast, the presence of serum factors or IgG in the incubation medium did not seem to influence the recognition of DTSP-modified erythrocytes by macrophages. These results seem to indicate a different mechanism of recognition for the erythrocytes modified with either one or the other band 3 cross-linker. In summary, the unique use of both band 3 cross-linkers procedures can be used to target carrier erythrocytes conveying active compounds to macrophages, with possible therapeutical applications. Different mechanisms of induction of macrophage recognition by these band 3 cross-linkers could reveal differential actions on erythrocytes or the involvement of different factors in the recognition process.