Recognition of carbohyrates by T lymphocytes in lymphocyte activation

The purpose of this investigation was to elucidate the role of the oligosaccharides of Class II MHC glycoproteins in allostimulation. Plasma membranes (PM) from the Daudi cell line were chemically deglycosylated using anhydrous hydrogen fluoride (HF). Subsequently, native and deglycosylated (dgl) Class II MHC molecules were affinity purified from their respective PM and inserted into the PM of peripheral blood leukocytes (PBL) which were used as stimulators in the mixed leukocyte reaction (MLR). Stimulator and responder cells were from the same donor. Both forms of the antigen were found to elicit a proliferative and cytolytic (CML) response but the dgl antigen did so to a lesser extent. Thus, it seemed as though the oligosaccharide side chains of Class II MHC molecules may not be required for allostimulation. A similar reduction in the cytolytic response was obtained when effector cells generated by the native antigen were used against targets that were stripped of N-linked oligosaccharides by tunicamycin (TM) pretreatment. Twenty-four clones were raised against the native antigen. Three clones gave proliferative responses only to the native antigen while two clones responded equally to both native and dgl antigen. In CML studies the three clones lysed normal targets but failed to lyse TM-treated target cells while the two clones did not discriminate between the two targets. Accordingly, the three clones were termed anti-MHC oligosaccharide clones while the two clones were termed anti-MHC polypeptide clones. In inhibition of CML experiments using the dgl supernatant which contained Daudi PM oligosaccharide or using a anti-MHC class II monoclonal antibody; CML reactivity of the anti-MHC oligosaccharide clones was blocked by the dgl supernatant but not by the anti-MHC MoAb. On the other hand the anti-MHC polypeptide clones were only inhibited by the anti-MHC MoAb whether against intact or TM-treated targets. These studies strongly indicate that glycoconjugates o