Carbohydrates mediate tissue type-specific membrane activity for Thy-1 alloantibody response

Thymocyte membrane fragments (TMF) but not brain cell membrane fragments (BMF) show a unique activity for inducing Thy-1 alloantibody response. Treatment of TMF with α-mannosidase or endoglycosidase-H greatly diminished this activity but not the serological Thy-1 antigenicity. This suggested that the TMF activity is supported by high mannose type N-linked oligosaccharides on the TMF. On the other hand, treatment with neuraminidase made otherwise silent BMF definitely active for the antibody response and this activity was abolished by further treatment with endoglycosidase-D. This demonstrated that BMF have a latent activity which is mediated by complex type N-linked oligosaccharides normally masked with slalic acids, It was concluded that two types of N-linked oligosaccharides as well as slalic acids mediate at least in part the tissue type-specific membrane activity for Thy-1 alloantibody response.