Potent immunosuppression by secretory/excretory products of larvae from the sheep blowfly Lucilia cuprina

Abstract

Secretory/excretory products (sec/ex) of parasitic larvae of the sheep blowfly Lucilia cuprina potently inhibited proliferation of peripheral blood leucocytes stimulated by mitogens in vitro. Suppression of proliferation was not due to irreversible damage because cells cultured for 24 h in high concentrations of sec/ex appeared viable (assessed by Trypan blue exclusion) and did not show impaired proliferation after washing. Furthermore, suppression induced by sec/ex could be overcome by increasing concentrations of mitogen. The inhibitory activity could be demonstrated in cultures where sec/ex was added at different times during the culture period. Inhibitory activities in sec/ex were heat-labile and sensitive to treatment with trypsin. In addition to effects in vitro, sec/ex was strongly immunosuppressive in vivo. Sheep given combined injections of myoglobin and sec/ex had markedly lower anti-myoglobin antibody levels in sera than sheep that received injections of myoglobin alone. There was no significant antibody response to sec/ex itself. Immunosuppressive moieties in sec/ex produced by blowfly larvae may promote parasite survival by inhibiting the immune response of host sheep.

The role of sphingolipids in respiratory disease

“…The importance of ASMase for the development of ALI has been shown in many models such as pulmonary edema caused by PAF [Kerlin and East, 1992], lipopolysaccharide (LPS) [Claus et al 2005;Goggel et al 2004;Haimovitz-Friedman et al 1997], acid instillation [Goggel et al 2004] or repeated lung lavage [von Bismarck et al 2008]. Importantly, impairment of ASMase improved not only vascular barrier functions (as shown in all studies above), but also oxygenation [von Bismarck et al 2008;Goggel et al 2004].…”

Oestrus ovis (Diptera: Oestridae): effects of larval excretory/secretory products on nitric oxide production by murine RAW 264·7 macrophages

“…Pruett (3) showed that Hypodermin A cleaves bovine IgG. In the same manner, Lucilia cuprina (Calliphoridae) larvae contain digestive tryptic and chymotryptic proteases involved in larval nutrition (4) and avoidment of cellular (5,6) and humoral immune responses, with cleavage of IgG (7–9). Moreover, excretion of ammonia by L. cuprina larvae suppresses immunity in sheep (10).…”

The immunobiology of myiasis infections – whatever happened to vaccination?

“…With respect to the sheep blowfly, the ability of the larvae to degrade host immunoglobulin (62) is one clear example whereby the larvae are capable of avoiding the host humoral immune response. In addition, excretory/secretory (E/S) products produced by the larvae have been shown to be able to directly influence the immune response at both the cellular and humoral levels (66). The results from this study demonstrated that the proliferation of ovine lymphocytes could be suppressed in vitro following exposure to the larval products, but interestingly this suppression could be reversed.…”