In contrast, when eosinophils were incubated in wells coated with IgG (100 g/ml) in the presence of the ESP, eosinophil degranulation was reduced about 50% from that of cells incubated in wells coated with IgG alone (Fig
In contrast, when eosinophils were incubated in wells coated with IgG (100 g/ml) in the presence of the ESP, eosinophil degranulation was reduced about 50% from that of cells incubated in wells coated with IgG alone (Fig. by PwNEM attenuate both activation and degranulation of eosinophils stimulated with IgG. Therefore, the cysteine proteases produced by tissue-invasive helminth larvae play important functions in evasion of IgG-dependent eosinophil helminthotoxicity and in reduction of eosinophil-associated cells inflammation during the migratory period. Eosinophils are known to be important effector cells in the sponsor defense against helminth parasites (15). They can damage or destroy helminth worms by antibody-dependent cellular cytotoxicity mechanisms in in vitro ethnicities (5, 12, 28). Although the exact mechanisms by which eosinophils destroy helminth parasites in vivo are not completely recognized, degranulation of adhering eosinophils has been suggested to play a major part (13, 25). For example, eosinophil granule proteins, such as major basic protein, eosinophil peroxidase, and eosinophil cationic protein, directly damage a variety of helminth parasites (6, 16, 22, 37). Once the eosinophil offers migrated into inflamed cells in vivo, it becomes activated and releases various mediators, such as reactive oxygen intermediates, lipid mediators, and cytotoxic granular proteins (14). Recently the activators and regulators of eosinophil functions have been shown. Several in vitro studies suggest that immobilized immunoglobulin G (IgG) 4-Aminobutyric acid (21, 27), secretory IgA (1), platelet-activating element (24), and cytokines, such as interleukin 5 (IL-5), IL-3, granulocyte-macrophage colony-stimulating element, and RANTES (19), are effective stimuli for activation of human being eosinophils. Even though triggered eosinophils are clearly involved in the killing of the worms in vitro, it is interesting to note that tissue-dwelling helminth parasites adapted for the human being sponsor can reinfect and/or survive 4-Aminobutyric acid for many years actually in the activation of the sponsor immune reactions. Therefore, tissue-invading helminthic worms may have an immune escape mechanism of down-regulation of eosinophil effector functions, therefore enabling the worm 4-Aminobutyric acid to pass through sponsor immune defenses unmolested. Excretory-secretory products (ESP) produced by tissue-invasive helminth larvae contain a large quantity of proteolytic enzymes, which are essential for worm maturation (35), migration in sponsor cells (29), and modulation of the immune response (3, 7, 8, 23). In vitro cleavage of IgG by cysteine proteases in the ESP secreted by tissue-invasive helminth larvae has been correlated with immune escape from antibody-dependent cellular toxicity. For example, cysteine proteases produced by newly excysted metacercariae (PwNEM) are capable of degrading sponsor IgG in vitro (8). Cysteine proteases of invasive larvae of additional helminths, such as (3) or (23), have also been known to cleave IgG molecules. Moreover, cysteine proteases secreted Mouse monoclonal to CD15.DW3 reacts with CD15 (3-FAL ), a 220 kDa carbohydrate structure, also called X-hapten. CD15 is expressed on greater than 95% of granulocytes including neutrophils and eosinophils and to a varying degree on monodytes, but not on lymphocytes or basophils. CD15 antigen is important for direct carbohydrate-carbohydrate interaction and plays a role in mediating phagocytosis, bactericidal activity and chemotaxis by in vitro prevent parasite-specific antibody-mediated eosinophil attachment to newly excysted juvenile 4-Aminobutyric acid worms (7). Consequently, these findings led us to speculate that cysteine protease secreted from the tissue-invasive helminth parasites may improve the effector functions of eosinophils in the presence of parasite-specific IgG. Freshly isolated eosinophils communicate only FcRII (18), and eosinophil activation induced by immobilized IgG is definitely mediated through FcRII (20). IgG bound to Sepharose beads (1) or IgG applied to cells tradition plates (21) causes degranulation and superoxide production of human being eosinophils. In contrast to these reactions of eosinophils to solid-phase IgG, little is known concerning the functions of parasite-secreted cysteine proteases that might alter the effector functions of eosinophils stimulated with IgG. The understanding of mechanisms used by cysteine proteases secreted from the PwNEM 4-Aminobutyric acid to moderate IgG-induced effector functions of eosinophils provides a important idea that eosinophils may not serve as strong effector cells in cells helminth infections. To show this hypothesis, we investigated whether cysteine proteases released from the PwNEM, which cause pulmonary or extrapulmonary paragonimiasis in human beings, could attenuate degranulation and superoxide production of eosinophils stimulated with IgG. MATERIALS AND METHODS Preparation of ESP produced by PwNEM. Metacercariae of were collected from naturally infected freshwater crayfish, metacercariae was prepared by transferring 5,000 newly excysted metacercariae into 5 ml of physiological saline and incubating at 37C inside a 5% CO2.