Alpha 2-macroglobulin and alpha 2-macroglobulin/proteinase complexes in human seminal fluid.

OBJECTIVE: To determine the broad-spectrum proteinase inhibitor alpha 2-macroglobulin (alpha 2M) and its functional subforms, i.e., free alpha 2M and alpha 2M/proteinase complexes, in human seminal fluid by using specific enzyme immunoassay systems. SETTING: The study has been performed in the Andrology Department of the Dermatology Clinics and the Laboratory of Immunopathology of the Institute of Immunology. PATIENTS, PARTICIPATES: Routine patients attending the Andrology Department. INTERVENTIONS: The data have been obtained without particular interventions before or after collection of seminal fluid. MAIN OUTCOME MEASURES: The aim of the study was to determine whether alpha 2M or alpha 2M/proteinase complexes are present in human seminal fluid. RESULTS: The concentration of total alpha 2M in human seminal fluid ranged from 1 to greater than 1,000 ng/mL, and between 56% and 85% of the inhibitor was complexed with proteinases. CONCLUSIONS: These findings show that alpha 2M and alpha 2M/proteinase complexes have to be considered as functionally relevant biomolecules in male genital tract secretions.