Soluble interleukin-2 receptor (sIL-2R), eosinophil cationic protein (ECP), the lymphoproliferative response to house-dust mite (HDM), adhesion to human umbilical vein endothelial cells (HUVEC), and lymphocyte membrane markers were studied in three groups of children: healthy children, asthmatic children without hyposensitization (HS), and asthmatic children with HS. HS was associated with significantly lower numbers of peripheral blood eosinophils (PBE) and lower sIL-2R serum levels and with a tendency to lower ECP serum levels and lymphoproliferative response to HDM. There were no changes in the T-lymphocyte phenotypic markers CD4 and CD8 among the three groups. The interleukin-2 receptor (IL-2R, CD25) on HDM-stimulated T lymphocytes increased over unstimulated T lymphocytes in the three groups. The CD25 expression was higher on HDM-stimulated lymphocytes in both asthmatic groups than in healthy children. Adhesion of lymphocytes on HUVEC increased significantly after HDM stimulation in asthmatic children without HS, whereas no change was observed in the two other groups. However, there was no change in the expression of adhesion molecules CD29 and CD11a on lymphocytes in either of the groups. This study provides further evidence that HS can modify lymphocyte and eosinophil functions.