EFFECT OF AN ASTHMATIC ATTACK ON CD23 AND CD21 EXPRESSION ON LYMPHOCYTES FROM ALLERGIC CHILDREN DURING THE ALLERGEN SEASON

Background The overproduction of IgE antibodies by atopic individuals in response to inhaled aeroallergen, forms the basis of an allergic disease. Furthermore, the exposure to allergen might trigger the symptom exacerbation. Objective In children with bronchial asthma, the possible effects of seasonal, natural exposure to allergen on the expression of CD21 and CD23 antigens on B lymphocytes, and on the expression of HLA-DR, CD45RA and CD45RO on CD4(+) T cells were investigated. Methods Heparinized blood samples were obtained from 15 children with bronchial asthma allergic to Dermatophagoides pteronyssinus (Der p) at the time of an acute asthmatic attack and 2-4 weeks after the attack when the peak expiratory flow (PEF) was stabilized. The samples were analysed on a flow cytometer after the three-colour immunofluorescence staining had been performed. Results The increased proportion of B cells expressing CD23 antigen was found at the time of attack rather than after stabilization. Serum levels of total and Der p-specific IgE increased 2-4 weeks after the asthmatic attack. This increase was accompanied by a further increase in the expression of CD23 antigen on CD21(-) B lymphocytes. In 10 out of 15 tested children, we found CD23 expressed on CD4(+)HLA-DR(+) T cells during the asthmatic attack. No significant difference was found in the expression of CD45RA and CD45RO antigens. Conclusion Since we have previously demonstrated the increased percentage of CD23 on CD21(-) B cells in allergic children as compared with controls, we speculate that natural exposure to the allergen which caused the increase in total and specific IgE levels might be related to the increased expression of CD23 on CD21(-) B cells.