Impaired lymphocyte transformation in intestinal lymphangiectasia: evidence for at least two functionally distinct lymphocyte populations in man

Intestinal lymphangiectasia is a disease characterized by hypoproteinemia and edema resulting from protein-losing gastroenteropathy secondary to abnormal intestinal lymphatics. Immunologic abnormalities associated with this disease include hypogammaglobulinemia, lymphocytopenia, skin anergy, and impaired allograft rejection. In the present study, the in vitro blastogenic transformation of lymphocytes from 12 patients with intestinal lymphangiectasia was assessed in order to gain insight into the mechanism of the cellular immune defect in this disease. Peripheral blood lymphocytes from patients with intestinal lymphagiectasia showed impaired in vitro transformation to nonspecific mitogens, specific antigens, and allogeneic cells when compared to equal numbers of cells from normal individuals. Patients with the most deficient in vitro reactivity tended to have the lowest serum albumin concentration and the lowest absolute lymphocyte count. Lymphocytes obtained from chylous effusions in each of the four patients studied transformed more vigorously than peripheral blood cells from the same patients. These results may be explained by the loss of recirculating, long-lived lymphocytes into the gastrointestinal tract, resulting in a relative depletion of the population of lymphocytes necessary for in vitro blast transformation. This disease thus represents a clinical analogue of animals with experimental thoracic duct drainage, and provides evidence for the existence, in man, of two functionally distinct lymphocyte populations. In addition, these findings establish a new mechanism of impaired delayed hypersensitivity and defective in vitro lymphocyte transformation, i.e. the gastrointestinal loss and consequent depletion of the long-lived, recirculating population of lymphocytes from the peripheral lymphocyte pool.