DIFFERENTIAL INDUCTION OF MACROPHAGE RECOGNITION OF CARRIER ERYTHROCYTES BY TREATMENT WITH BAND-3 CROSS-LINKERS

Mouse native and hypotonically loaded erythrocytes were treated with t wo cross-linking reagents: bis(sulphosuccinimidyl)suberate (BS3)- and 3,3'-dithiobis(sulphosuccinimidyl propionate) (DTSP), excluding cluste ring agents. Microscopic analyses revealed that band 3 cross-linked na tive and hypotonically loaded erythrocytes are more strongly recognize d by peritoneal macrophages than native and loaded erythrocytes as a r esult of the cross-linking of band 3 protein in accordance with studie s in vivo. Macrophage-recognition analyses of Cr-51-labelled erythrocy tes also demonstrated increased recognition of cross-linked and cross- linked loaded erythrocytes, This shows that the only action of these t wo 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 erythrocyt es by macrophages is dependent on the presence or absence of homologou s serum or immunoglobulins. In contrast, the presence of serum factors or IgG in the incubation medium did not seem to influence the recogni tion 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 in duction of macrophage recognition by these band 3 crosslinkers could r eveal differential actions on erythrocytes or the involvement of diffe rent factors in the recognition process.