Abstract
Purpose: :
Mice, rats and rabbits are frequently used for studies of lacrimal gland (LG) function. Our goal was to determine whether histoarchitectural and immunological features distinguish each animal model.
Methods: :
LGs were collected from young adult female Lewis rats, C57 and BALB/C mice, and New Zealand White rabbits. Rabbits did not exceed ages of 8 months; rats and mice did not exceed 4 months. Cytokine mRNA abundances relative to GAPDH mRNA abundance were determined by real time RT-PCR with species-specific primers and probes.
Results: :
Whereas LGs are uniformly comprised of acini drained by ducts, acinar lumens are ovoid in rabbits, but often are very small and complexly folded, with lumenal evaginations extending nearly to the basal lamina in mice. Acini in rabbits are enveloped by a much richer connective tissue bed than in mice and rats. Plasma cells dominate the interstitium of rabbits, whereas mast cells are rare or absent. In contrast, mast cells are numerous in the interstitium of mice and rats, while plasma cells are not prominent. Segments of interlobular ducts are often enveloped by foci of lymphocytes in rabbits, but not in mice or rats. Relative abundances of TGF-β1 were more than 3-fold greater in rats than in rabbits. Values for IL-10 were 3-fold greater in rats than in rabbits.
Conclusions: :
LG histoarchitecture and immunoarchitecture differ fundamentally between rodents and lagomorphs. While TGF-β1 may be the predominant immunoregulatory cytokine in both orders, the role IL-10 plays in local immune regulation may be considerably more prominent in the lagomorphs. Whereas LGs regulate and maintain the health of the ocular surface in all animal models, both the mechanisms they use to avoid autoimmune inflammation and the pathologies that result when these mechanisms fail may differ significantly. Support: EY005801, EY010550, EY01773. Commercial relationships: none
Keywords: lacrimal gland • immunomodulation/immunoregulation • microscopy: electron microscopy