Feline immunodeficiency virus (FIV)
infection is characterized by chronic overactivation of immune and inflammatory system, resulting in anergic state and dysfunction of immune cells.
Lactoferrin (LF), a
glycoprotein present in exocrine secretions and neutrophils, plays an important role in host defense system. Our previous study showed that
oral administration of bovine LF (bLF) suppressed oral
inflammation, improved the clinical symptoms and decreased serum
gamma-globulin as a marker of
inflammation in FIV-infected cats with intractable
stomatitis. The anti-inflammatory effect was partly involved in regulation of neutrophil function by bLF. In this study, to clarify the relationship between anti-inflammatory effects of bLF and peripheral blood mononuclear cells (PBMC), we examined the effect of bLF on proliferation, cell cycle progression and
cytokine expression in
mitogen-activated PBMC. MTT [3-(4,5-dimethylthiazol-2-yl)- 2,5-diphenyl tetrazolium
bromide] assay showed that bLF inhibited the
concanavalin A (ConA)-induced cell proliferation in FIV-infected cats with the asymptomatic carrier and
AIDS-related complex (
ARC) phase. Bovine LF restored ConA-induced cell cycle progression and resulted in suppression of the induced apoptosis in feline PBMC. Real-time RT-PCR showed that bLF suppressed ConA-induced expression of
interferon-gamma and
interleukin-2 in cells of the
ARC group regardless of the time of its addition to the medium. These results suggest the hypothesis that
therapy with bLF may have the potential to improve and protect functions of overactivated lymphocytes by modulating the cell proliferation, cell cycle and
cytokines expression in cats in terminal stage of FIV
infection.