Lactoferrin, a potent tryptase inhibitor, abolishes late-phase airway responses in allergic sheep

Kyle C. Elrod, William R. Moore, William M. Abraham, Richard D. Tanaka

Research output: Contribution to journalArticlepeer-review

87 Scopus citations


Tryptase, a serine protease released exclusively from activated mast cells, has been implicated as a potential causative agent in asthma. Enzymatically active tryptase is comprised of four subunits, and heparin stabilizes the associated tetramer. Lactoferrin, a cationic protein released from activated neutrophils, binds tightly to heparin, therefore we investigated lactoferrin as an inhibitor of tryptase and found that it is both a potent (K1 is 24 nM) and selective inhibitor. Size exclusion chromatography studies revealed that lactoferrin disrupted the quaternary structure of active tryptase. Lactoferrin was tested in an allergic sheep model of asthma; aerosolized lactoferrin (10 mg in 3 ml phosphatebuffered saline, 0.5 h before as well as 4 and 24 h after inhalation challenge by Ascaris suum) abolished both late-phase bronchoconstriction (no significant increase in specific lung resistance 4 to 8 h following provocation, p < 0.05 versus vehicle treatment) and airway hyperresponsiveness (no detectable increase in airway sensitivity to carbachol challenge 24 h after antigen challenge, p < 0.05 versus vehicle). These data suggest tryptase involvement in both late-phase bronchoconstriction and airway hyperreactivity and furthermore suggest that a physiological function of neutrophil lactoferrin is the inhibition of tryptase released from mast cells.

Original languageEnglish (US)
Pages (from-to)375-381
Number of pages7
JournalAmerican journal of respiratory and critical care medicine
Issue number2 I
StatePublished - Jan 1 1997

ASJC Scopus subject areas

  • Pulmonary and Respiratory Medicine
  • Critical Care and Intensive Care Medicine


Dive into the research topics of 'Lactoferrin, a potent tryptase inhibitor, abolishes late-phase airway responses in allergic sheep'. Together they form a unique fingerprint.

Cite this