A large range of immunological investigations in patients with extrinsic or intrinsic asthma showed higher leucocyte counts in intrinsic asthma. Blood sputum eosinophilia were almost equally frequent.
Immediate skin responses to inhalant antigens are seldom present in intrinsic asthma, but delayed responses to bacterial antigens, endotoxins, Candida albicans and aspiryl–PPL are frequently positive. This correlates with the frequent presence of precipitins and in vitro stimulation of lymphocytes, and the production of macrophage migration inhibition factor by most of these substances. These results suggest that bacterial factors may play a prominent role as aetiological agents in at least some cases of intrinsic asthma. In intrinsic asthma there was a high incidence of tissue autoantibodies, whereas the incidence was negligible in patients with atopic asthma.
The level of serum immunoglobulins was not statistically different between the two groups of patients except for IgE.
The patients with intrinsic asthma showed a favorable response to sodium cromoglycate.