Reduction of increased serum neutrophil chemotactic activity following effective hyposensitization in house dust mite allergy


Dr P. W. Ewan, Molecular Immunopathology Unit, MRC Centre, Hills Road, Cambridge CB2 2QH.


Changes in the level of serum neutrophil chemotactic activity (S-NCA) were investigated in 20 subjects with allergic rhinitis, with or without asthma, undergoing clinically effective hyposensitization to house dust mite with Pharmalgen®Dermatophagoides pteronyssinus. Two control groups were studied: 28 subjects with allergic rhinitis, with or without asthma, receiving placebo injections for 1 yr in a double-blind controlled trial with Pharmalgen®D. pteronyssinus (from whom the actively, treated group in this study were recruited), and eight non-atopic asymptomatic controls. S-NCA and serum IgE specific to D. pteronyssinus were measured in the subjects before, during (3–6 months) and 12 months after treatment, and once in the non-atopic controls. The mean S-NCA was significantly higher (0.01 > P > 0.001) in subjects before treatment (mean±s.e. = 63.8 ± 3.6 arbitrary units of migration (AUM)) compared with the non-atopic controls (48.5 ± 3.7 AUM), but had fallen to normal levels after 6 months (46.8 ± 4.0 AUM) and 12 months treatment (45.2 ± 3.8 AUM). The levels of S-NCA in the placebo treated group were significantly higher than normal at the start of treatment (69.2 ± 4.1) and remained raised throughout the 12 months treatment. In the actively treated group, the level of S-NCA had fallen in 18 out of 19 subjects after 12 months immunotherapy, and was unaltered in one. Mean levels of D. pteronyssinus IgE rose during the first 6 months and declined to initial levels by the end of the treatment. We suggest that the elevated S-NCA may play a role in the maintenance of the allergic state through the induction of the late-phase reaction; that the abnormal S-NCA production is reduced by effective hyposensitization, and that measurement of S-NCA may be useful to monitor hyposensitization therapy. Complete characterization of S-NCA and the mechanisms of its control remain to be investigated.