Study objectives: To investigate the roles of humanα
-defensin (HAD), human β-defensin (HBD)-1, and HBD-2, novel
antimicrobial peptides, in patients with Mycobacterium
avium-intracellulare infection (MAI).
Patients: The study included 25 patients (10 men) with MAI
who visited our hospital between June 1998 and August 1999.
Measurements and results: In patients with pulmonary MAI,
we measured HAD and HBD-1, and HBD-2 levels in plasma and in BAL fluid
(BALF) by radioimmunoassay. Plasma concentrations of HAD and HBD-2 in
those patients were higher than those in control subjects, whereas
HBD-1 levels were similar to those in the control subjects. High levels
of HAD and HBD-2, but not HBD-1, also were observed in the BALF of MAI
patients. There was a positive correlation between HAD and interleukin
(IL)-8 concentrations in the BALF of patients with MAI. BALF HBD-2
concentrations also correlated positively with those of plasma HBD-2
and BALF IL-1β in MAI patients. Patients with cavity formation on the
chest roentgenogram had higher HAD and HBD-2 levels in their BALF than
those of patients without cavity formation. Treatment with
clarithromycin combined with two or three other antibiotics, including
ethambutol, rifampicin, ofloxacin, or ciprofloxacin, for at least 6
months resulted in a significant fall in plasma HBD-2 concentrations in
responders, but not in nonresponders.
findings suggest that HAD and HBD-2 may participate in host defense and
local remodeling of the respiratory tract in patients with MAI and that
plasma HBD-2 levels may be a useful marker of disease activity in
patients with pulmonary MAI.