[Markers of lymphocyte activation in interstitial pulmonary disease]

A lymphocytic alveolitis is a common stage in a number of types of interstitial pneumonia where the lymphocytes accumulate in the alveoli and play a major pathogenic role by the regulation or activation of the inflammatory reaction, controlling the outcome either to healing, chronicity or fibrosis. A study of lymphocytes obtained by broncho-alveolar lavage enables the study of different parameters whose functional value is discussed from information derived form in vitro models. These models show the need for activating signals acting in a sequential manner on cells whose function and mode of response are remarkably varied. Three successive phases may be defined during activation: first a "membrane" stage with changes in the lipid (in the metabolism of arachidonic acid) and kinetic framework, a second phase corresponds to the beginning of "blastic transformation" with the production of lymphocytes, an increase in the protein content and RNA (phase G1), then a third stage of DNA synthesis (phase S-G2) preceding cell division; it is necessary to have new markers of differentiation. The joint study of the phases of cell cycles and the antigenic expression of differentiation, identified by monoclonal antibodies within a heterogeneous population nowadays benefit from techniques of cytofluorimetry. The methods combined with a measure of mediators produced (interleukins) or the non-specific markers of activation by macrophages ought to lead to a definition of initial stages of the clinical immunology of alveolitis. Finally these methods permit the development of cellular immunopharmacology which to open the possibilities of new forms of treatment.