Evaluation of Immunotherapy in House Dust Mite Asthma.

¹SA Shoeb, ¹HM Safouh, ²ZM Radwan and ³WA Mostafa.

Departments of ¹Microbiology and Immunology, ²Pediatrics, Faculty of Medicine, Cairo University and ³Military Hospital for Civil Workers.

The study was conducted on 53 asthmatic children (5-13 years old) all of whom were found to have positive skin tests (ST) to House Dust Mite extract (HDM). They were allocated randomly to 2 groups. Group A (32 patients) received specific immunotherapy (SIT) with locally prepared HDM extracts for 18 months, while group B received placebo. Both groups were repeatedly assessed for clinical score, ST positivity, serum total and mite-specific IgE levels, serum IgG4 levels and peripheral blood CD4/CD8 T cell ratios. The clinical and humoral parameters were assessed at 0, 3, 6, 12 & 18 months, while ST and CD4/CD8 ratios were analyzed only at 0 & 18 months after therapy. Statistical analysis of clinical scores showed that the scores of group A had decreased significantly by time (p < 0.001). ST positivity also showed significant reduction by the end of treatment in group A (p < 0.001) but not in group B (p>0.05). In addition the mean total and mite-specific IgE levels showed significant reduction after therapy (p < 0.001), with concomitant increase in mean serum IgG4 level of group A. In contrast, there was no significant change in CD4/CD8 ratios of either group. These findings confirm the value of SIT with locally prepared mite extracts in HDM-induced asthma. The study also sheds a light on the possible mechanisms by which immuno therapy may reduce unresponsiveness and suggests that one of these mechanisms might involve a decrease in IgE and an increase in IgG blocking antibodies.