Post-traumatic pleural effusion: demonstration of local complement consumption.

The present case report describes a 27-year-old patient who presented with post-traumatic pleural effusion. Analysis of the pleural fluid showed hypereosinophilia (990 mm-3), a decreased level of total complement, and decreased levels of C3 and C4 fractions (less than 50% of normal serum levels), indicating a local consumption mechanism for complement. Complement serum levels (CH50, C3, C4) were normal. All other aetiologic possibilities were eliminated. This case suggests that the immunopathological mechanism of post-traumatic pleural effusion may involve activation of the classical pathway of complement and a recruitment of inflammatory cells such as eosinophils.