Immunohistochemical detection of sialyl Le(x) antigen on mucosal Langerhans cells of human oral mucosa following neuraminidase pretreatment

Abstract

Histochemical assessment of selected carbohydrate sequences on Langerhans cells of human oral mucosa was made by combined use of enzyme digestion and immunostaining with monoclonal antibodies against specific carbohydrate structures. In both frozen sections and epithelial sheets without the enzyme pretreatment, mucosal Langerhans cells, identified by positive staining with anti-CD1a and HLA-DR antibodies, did not express any carbohydrate antigens on their surface. In contrast, following neuraminidase pretreatment of both types of material, the fucosylated type 2 chain (Le(x)) became detectable on Langerhans cells, indicating that sialic acid is the terminal residue of this sequence. Other enzymes were ineffective in this apparent unmasking, and the staining patterns of the other related carbohydrate sequences (Le(y)+, Le(a), Le(b)) remained unaffected by pretreatment with any of the enzymes used. These findings suggest that the mucosal Langerhans cells possess a unique carbohydrate chain, the sialyl fucosylated type 2 sequence (sialyl Le(x) antigen).