CONCENTRATIONS OF ALPHA-1-PROTEINASE INHIBITOR AND ALPHA-2-MACROGLOBULIN IN SERUM AND LUNG SECRETIONS OF INTUBATED INFANTS

  • 1 January 1984
    • journal article
    • research article
    • Vol. 18  (1) , 35-40
Abstract
To determine the relative importance of the 2 proteinase inhibitors, .alpha.1-proteinase inhibitor (.alpha.1PI) and .alpha.2-macroglobulin (.alpha.2M), in defending the infant [human] lung against proteolytic attack, concentrations of .alpha.1PI and .alpha.2M were measured in both serum and lung secretions of infants intubated for respiratory insufficiency. The concentration of each of the proteinase inhibitors in lung secretions was also compared with the serum concentrations of the proteinase inhibitor on the same day. Serum and secretions of all infants contained quantifiable levels of .alpha.1PI. All serum samples had measurable amounts of .alpha.2M. Ninety-two percent of the infants and 78% of all secretion samples tested contained .alpha.2M. Molar ratios of .alpha.1PI/albumin did not change as a function of gestational age in serum or secretions. Serum .alpha.2M/albumin also remained unchanged but in lung secretions .alpha.2M/albumin increased significantly with gestational age. With increasing postnatal age up to 44 days, mean levels of serum .alpha.1PI, .alpha.1PI/albumin, .alpha.2M and .alpha.2M/albumin increased. There was a greater increase in serum .alpha.2M than in .alpha.1PI as evidenced by a decreasing molar ratio of .alpha.1PI/.alpha.2M with increasing postnatal age. In lung secretions, only .alpha.1PI/albumin increased with postnatal age. Mean values for the molar ratio of .alpha.1PI/.alpha.2M in lung secretions ranged from 17 at 1-5 d [day] to 22 at 11-44 d compared with the ratio of 200 reported for healthy adults.