[Retrospective study of 55 patients with circulating blood T gama/delta lymphocytosis]

Gamma/delta T lymphocytes constitute a singular population due to their particular antigenic recognition and their localization inside the epithelium. Their functions are complementary to those of the alpha/beta T-cells and they are involved in the defense and regulation of the immune system. Their role in human diseases is not very well understood and the aim of our study was to analyze a population of patients with a peripheral gamma/delta T-cell lymphocytosis.

The study included 55 patients, recruited from 1997 to 2000, with a peripheral gamma/delta T lymphocytosis (defined by a proportion of gamma/delta T-cells of over 10% of total peripheral T lymphocytes). Analysis of the lymphocyte population was obtained by cytometry after peripheral blood sampling.

Three main groups of diseases were observed: infectious diseases (viral infections and tuberculosis), inflammatory diseases (sarcoidosis and autoimmune diseases) and blood diseases (monoclonal gammopathies and hemopathies). Persistence of gamma/delta T lymphocytosis was dependent on the underlying disease (transitional when associated with an infectious disease and lasting when associated with sarcoidosis). The rest of the immunophenotyping analysis was usually normal.

Our results confirm the data published in the literature concerning the role of the gamma/delta T lymphocytes in infectious, inflammatory and autoimmune diseases and neoplasias. These data are in agreement with the cytotoxic and regular functions of these lymphocytes.