The measuring of "respiratory-membrane permeability" and local production of immunoglobulins and antibodies by means of an analysis of sputum

When measuring the exudation of serum proteins and the local production of immunoglobulins and antibodies within the lung by means of an analysis of sputum, the permeability properties of the respiratory membrane should be taken into account. In this paper, we describe the "loss of size selectivity" that usually accompanies an increased permeability on the part of the respiratory membrane. This phenomenon enables us to measure respiratory membrane permeability independently of the sputum water content. Consequences with regard to discrimination between leakage from the circulation and/or local production of immunoglobulins and antibodies are discussed. Sequential studies which take these factors into account may provide insights into the extent of local inflammatory reactions in individual patients.