Subsets of epidermal Langerhans cells as defined by lectin binding profiles

In this study we characterize the cell surface glycoconjugate moieties of strain 2 guinea pig epidermal Langerhans cells (LC) in single cell suspension by using a battery of 17 fluorescent lectins. All LC displayed binding sites for concanavalin A, succinylated concanavalin A, Lens culinaris agglutinin, Pisum sativum agglutinin, wheat germ agglutinin, succinylated wheat germ agglutinin, Griffonia simplicifolia agglutinin I, Ricinus communis agglutinin I, Phaseolus vulgaris E agglutinin, and Phaseolus vulgaris L agglutinin, but failed to bind Sophora japonica agglutinin (SJA), Dolichos biflorus agglutinin (DBA), and Ulex europaeus agglutinin I (UEA I). Neuraminidase pretreatment rendered LC reactive for SJA, but not for DBA and UEA I. The binding profiles of certain lectins point to the existence of LC subpopulations in that Griffonia simplicifolia I-B4 isolectin, peanut agglutinin (PNA), Helix pomatia agglutinin, and soybean agglutinin bound to only 80% (range 70-90%) of Ia-positive epidermal cells; binding sites for these lectins on primarily unreactive Ia-positive cells were unmasked when epidermal cells were treated with neuraminidase prior to lectin labeling. Ultrastructural PNA labeling studies revealed that the vast majority of Birbeck granule-containing LC displayed PNA binding sites, whereas indeterminate cells were consistently PNA-negative. Identification of carbohydrate configurations expressed on LC surfaces by lectin binding may provide a clue for the elucidation of the mechanisms of established LC functions and possibly the discovery of as yet unknown properties of this cell type.