Expression of CD23 antigen and its ligands in children with intrinsic and extrinsic asthma

The role of the low-affinity IgE receptor CD23 in immune reactions has been further emphasized by recent discoveries of novel surface ligands for CD23: CD21, CD11b, and CD11c. We previously observed the difference between the expression of CD23 and CD21 antigens in children suffering from extrinsic asthma when compared to healthy controls. In the present study, we investigated the expression of CD23 and its ligand CD21 on CD20⁺B cells in 44 asthmatic children (23 allergic and 21 nonallergic) using three-color immunofluorescence analysis. In addition, the expression of two other ligands for CD23, CD11b, and CD11c, on T cells (CD3⁺), a subpopulation of T cells (CD4⁺ and CD8⁺), natural killer cells (CD56⁺), and monocytes (CD14⁺) was tested by two-color immunofluorescence analysis in 12 allergic and 14 nonallergic children. We found that children with extrinsic asthma had higher levels of CD23⁺ B cells than those with intrinsic asthma. No difference was observed in the percentage of either CD23⁺CD21⁺ or CD23^- CD21⁺ B cells. The CD11b antigen was expressed on each tested population, but only on CD4⁺ T cells was CD11b significantly increased in children with extrinsic asthma. CD11c was expressed mainly on monocytes, and no difference was observed between tested groups. The increased percentage of CD11b antigen on CD4⁺ T cells and the increased percentage of CD23 antigen on B cells in children with extrinsic asthma provide further evidence of the immunologic differences between intrinsic and extrinsic asthma.