Glycoprotein profiles of macrophages at different stages of activation as revealed by lectin binding after electrophoretic separation

Glycoprotein profiles of rat macrophages (MΦ) at different stages of activation were studied by examining the reactivity of varous lectins to the glycoproteins separated by polyacrylamide gel electrophoresis. Ricinus communis agglutinin 1 (RCA1) revealed several components including glycoproteins of Mr 160 kDa and 65 kDa prominent in resident MΦ. A pokeweed mitogen (PWM) isolectin, Pa‐4, recognizes branched poly(N‐acetyllactosamine)‐type carbohydrate chains, and revealed a significant increase in glycoproteins of Mr ranging from 70 kDa to 150 kDa on thioglycolateelicited MΦ. Increased reactivity of PWM tothioglycolate‐elicited MΦ was observed by direct binding of 125I‐labeled Pa‐4 to intact or glutaraldehyde‐fixed MΦ. Histochemical staining of formaldehyde‐fixed MΦ in vitro with biotinylated Pa‐4 wasa consistent with the gel analysis, that is, resident MΦ had no reactivity while thioglycolate‐elicited MΦ showed slight reactivity. Alveolar and intratumoral MΦ bound more Pa‐4 than resident or thioglycolate‐elicited MΦ. The PWM isolectin may therefore serve as a marker for an early stage of MΦ activation.