Immune dysfunction in Atlantic bottlenose dolphins (Tursiops truncatus) with lobomycosis

Lobomycosis (Lacaziosis) occurs only in humans and dolphins under natural
conditions. We evaluated the immune status of eight dolphins with lobomycosis
and 40 healthy dolphins from the Indian River Lagoon (IRL), Florida.
Lobomycosis cases had multiple abnormalities in their immunologic parameters
when compared to healthy dolphins, The absolute number of circulating
lymphocytes and serum albumin concentration were reduced (P<0.05) while the
segmented neutrophils, alpha I, total beta, total gamma and total globulins were
increased (P<0.05). Although innate immunity was relatively intact and phagocytosis
and natural killer cell activity were not affected, the plasma lysozyme
concentrations were elevated in dolphins with lobomycosis (P<0.05). Adaptive
immunity was depressed with statistically significant decreases found in the
absolute numbers of CD4+ helper T cells and CDI9+ and C021 + B cells.
The ratios of CD2 + T cells to CD4 + cells and CD2 + to CD21 + cells were
increased (P =0.05 and P<0.05, respectively) and the numbers of lymphocytes
expressing MHC class II molecules was decreased in dolphins with lobomycosis
(P<0.05). Lymphocyte proliferation was reduced in response to stimulation with
lipopolysaccharide and concanavalin A (P<0.05). Antibody titers to Erysipelas
rhusiopathiae, a common marine micro-organism, were decreased (P<0.05). In
summary, dolphins with lobomycosis exhibit significant impairment in adaptive immunity.