Further studies on the heterogeneity of antigens recognised by CD-1 monoclonal antibodies: distribution of epitopes and analysis of serological binding patterns

The binding patterns of 28 monoclonal antibodies (MAB) recognizing antigens belonging to Cluster of Differentiation One (CD-1) were analyzed in order to investigate heterogeneity within this cluster. Competitive binding assays using radiolabelled MAB provided detailed information on CD-1 antigenic heterogeneity, and demonstrated that at lease six epitopic regions are recognised as CD-1 MAB. Further studies, based on single cell suspension immunofluorescence assays (using thymocytes and subclones on the cell line Molt-4), suggested that the majority of MAB studied could be serologically separated into three groups. In view of the most recent information that CD-1 MAB recognize at least three different early T-cell differentiation molecules, our results indicate that there are three or more distinct epitopes on the 'gp49'(HTA-1/CD-1a) molecule, two on the 'gp45'(HTA-3/CD-1b) molecule and one on 'gp43'(HTA-2/CD-1c).