T-, B- and Fc-gamma-receptor-bearing lymphocytes were detected using six different membrane markers in patients suffering from asthma having either normal or low serum IgA levels. E rosettes, aE rosettes and a human anti-T lymphocyte antiserum (HTLA) were used for T cell determination. In patients with low serum IgA levels E rosettes were significantly decreased. B lymphocytes were identified by EAC rosette formation and visualization of surface membrane immunoglobulins (SmIg). No significant difference was seen. Fc-gamma-receptor-bearing lymphocytes were assessed by the EA rosette assay and were significantly decreased in asthmatics with normal IgA levels. This result might be explained by the presence of immune complexes.