SPECIFIC IMMUNOTHERAPY DOWN-REGULATES PERIPHERAL-BLOOD CD4 AND CD8 T-LYMPHOCYTE ACTIVATION IN GRASS POLLEN-SENSITIVE ASTHMA

Several lines of evidence indicate that specific immunotherapy may act by modifying the immune responses of T-lymphocytes to the antigen. To evaluate the effect of specific immunotherapy on the activation of T- lymphocytes by cluster of differentiation cells (CD4+ and CD8+) in per ipheral blood, the expression of two surface activation markers, the p 55 interleukin-2 receptor (CD25) and human leucocyte antigen (HLA)-DR, was studied prospectively on circulating CD4+ and CD8+ T-cell subsets in subjects with grass-pollen sensitive asthma before and after 1 yr of treatment with specific immunotherapy, Twenty five asthmatic patien ts with pollen sensitivity other than grass, studied out of their poll en season, served as the control group. Specific immunotherapy improve d clinical indices of disease activity including symptom scores and me dication use during the pollen season of the treatment year. It had a marked effect in reducing the expression of the two activation markers , CD25 and HLA-DR, in both CD4+ (p=0.002 and p=0.005, respectively) an d CD8+ (p=0.01 and p=0,01, respectively) T-cell subsets, in parallel w ith a significant decrease in CD23 expression on B-cells (p=0.008) and in grass-specific immunoglobulin E levels (p=0,01) in the peripheral blood of subjects with grass pollen-sensitive asthma, The decreased T- lymphocyte activation observed in immunotherapy-treated subjects after the treatment year was significant (p=0.05) in comparison with the co ntrol group, These data add to the view that the efficacy of specific immunotherapy may be attributed to the downregulation of T-cell respon ses.