Low density lipoproteins and immunoglobulins in human pleural effusions.

Pleural effusions in patients with bacterial pleurisy contain low density lipoproteins (33 per cent of the blood serum LDL-concentration on average) but almost no very-low density lipoproteins (about 1 percent of the blood serum VLDL-concentration on average). Immunoglobulins are present in large amounts forming a series declining from the IgG (70 per cent of the blood serum concentration, found in effusions) to the IgM (50 per cent of the blood serum concentration). The observations are discussed in relation to morphological aspects of molecular transport through the capillary wall, and the consequences of the LDL- and IgL-accumulation in pleural fluids are briefly discussed.