Increase in peripheral blood 'null' cells in extrinsic bronchial asthma.

Lymphocyte subpopulations were measured in the peripheral blood of fifteen patients with extrinsic bronchial asthma and twenty-seven normal control subjects. No significant differences in the absolute numbers of relative proportions of T, B or K lymphocytes were found. Antibody-dependent lymphocyte-mediated cytotoxicity (K-cell activity) was also found to be normal. The proportion and absolute number of 'null' cells were significantly increased in the asthmatic group: this population did not correlate with serum IgE levels, the eosinophil count or the duration of disease. The significance of these results in relation to suppressor T-cell control of IgE formation is discussed.