Abnormalities of circulating T cell subsets in atopy: influence of specific immunotherapy.

Blood samples of patients with severe respiratory allergic diseases contain increased numbers of T cells bearing surface HLA-DR antigens, indicating the presence of activated T cells. In the same group of patients, MLR3 and MLR4, two monoclonal antibodies (Mab) directed to subsets of activated peripheral T cells, recognize T cell percentages within the normal range. Thus, it seems possible that specialized subsets of activated T cells (HLA-DR+/MLR3-MLR-) are represented in the peripheral blood of atopic patients. Such cells are lacking in patients after specific immunotherapy. Similar results--an increased percentage of 5/9+ T cells in untreated patients and normal counts of 5/9+ T cells in treated ones--were obtained in the two groups of patients by using another Mab, 5/9, which serves as a reliable marker of helper T cells in resting peripheral T lymphocytes. These data further support the concept of a T cell imbalance in allergic patients and suggest a possible role of specific immunotherapy in correcting the modification of peripheral T cell abnormalities.