Novel clinical and serological aspects in non-allergic asthma

We have recently observed that skin reactivity to autologous serum injection is common in patients with non-allergic asthma. However, clinical significance of skin reactivity to autologous serum remains to be defined.

To evaluate the possible relation between skin reactivity to autologous serum and clinical and laboratory characteristics in a series of patients with non-allergic asthma.

Fifty-five patients with non-allergic asthma underwent in vivo autologous serum skin test (ASST) and in vitro basophil histamine release assay using basophils from a normal donor. Clinical and laboratory characteristics including peripheral blood eosinophilia, antinuclear antibodies and total IgE concentration were evaluated. As control, ASST was performed in 10 allergic asthmatic patients, 10 patients with allergic rhinitis and 10 normal subjects.

ASST was positive in 29/55 non-allergic asthmatics (53%), whereas it was negative in all 30 control subjects (P<0.001). The sera of 6 out of 51 patients induced in vitro histamine release from autologous basophils. The sera from two patients induced histamine release from membrane IgE-stripped basophils. A significant predominance of female sex (83%) and a high incidence of antinuclear antibodies (ANA) positivity (55%) were found among ASST-positive patients.

These findings indicate that ASST is positive in about half patients with non-allergic asthma and that a proportion of patients (16%) has functional evidence of circulating histamine-releasing factors. In addition, predominance of female sex and frequent ANA positivity are in line with an autoimmune basis of non-allergic asthma.