Effect of anti-thymocyte serum on the eosinophil and lysophospholipase responses in mice infected with Trichinella spiralis

In vitro and in vivo effects of rabbit anti-thymocyte serum on circulating leucocytes and production of complement fixing antibodies in thymectomized Oncorhynchus mykiss (Walbaum) infected with Cryptobia salmositica Katz 1951

Rabbit anti-thymocyte serum (RATS) against thymocytes of rainbow trout was toxic to leucocytes from intact and thymectomized rainbow trout at 10 °C under in vitro conditions. The total number of leucocytes decreased significantly in 24 h after RATS was injected intraperitoneally into intact rainbow trout, but the number returned to pre-injection level within 1 week. RATS destroyed a lower percentage of leucocytes in thymectomized fish than in intact fish under both in vitro and in vivo conditions and the recovery in the number of leucocytes was slower in thymectomized fish. The parasitaemia, packed cell volume and production of complement fixing antibody in thymectomized and intact fish (injected with RATS before Cryptobia salmositica infection) were not significantly different from control fish (not injected with RATS), and they both acquired protective immunity against cryptobiosis on recovery. This indicates that RATS is not cytotoxic to B-like cells in the lymphoid tissue which produce complement fixing antibody against C. salmositica and that the protective antigen in C. salmositica seems to be thymus-independent.

Crystal structure of human Charcot-Leyden crystal protein, an eosinophil lysophospholipase, identifies it as a new member of the carbohydrate-binding family of galectins

BACKGROUND

The Charcot-Leyden crystal (CLC) protein is a major autocrystallizing constituent of human eosinophils and basophils, comprising approximately 10% of the total cellular protein in these granulocytes. Identification of the distinctive hexagonal bipyramidal crystals of CLC protein in body fluids and secretions has long been considered a hallmark of eosinophil-associated allergic inflammation. Although CLC protein possesses lysophospholipase activity, its role(s) in eosinophil or basophil function or associated inflammatory responses has remained speculative.

RESULTS

The crystal structure of the CLC protein has been determined at 1.8 A resolution using X-ray crystallography. The overall structural fold of CLC protein is highly similar to that of galectins -1 and -2, members of an animal lectin family formerly classified as S-type or S-Lac (soluble lactose-binding) lectins. This is the first structure of an eosinophil protein to be determined and the highest resolution structure so far determined for any member of the galectin family.

CONCLUSIONS

The CLC protein structure possesses a carbohydrate-recognition domain comprising most, but not all, of the carbohydrate-binding residues that are conserved among the galectins. The protein exhibits specific (albeit weak) carbohydrate-binding activity for simple saccharides including N-acetyl-D-glucosamine and lactose. Despite CLC protein having no significant sequence or structural similarities to other lysophospholipase catalytic triad has also been identified within the CLC structure, making it a unique dual-function polypeptide. These structural findings suggest a potential intracellular and/or extracellular role(s) for the galectin-associated activities of CLC protein in eosinophil and basophil function in allergic diseases and inflammation.

Genetic influences upon eosinophilia and resistance in mice infected with Trichinella spiralis

Genetic influences upon host variation in eosinophilia and resistance to helminth infection, and the relationship between these parameters, were investigated in 7 inbred and 1 hybrid strains of mice infected with Trichinella spiralis. Clear strain-dependent variations were observed in the maximum peripheral blood, bone marrow and spleen eosinophilia attained in infected animals. SWR, NIH and SJL strains of mice all gave high responses to infection; four congenic strains sharing the B10 background (C57BL10 [B10], B10.S, B10.G and B10.BR) were low responders. Some of the genes for high responsiveness appeared to be dominant, as F1 hybrids from high- and low-response phenotype parental strains showed intermediate to high responses to infection. Intestinal eosinophilia showed no correlation with either peripheral blood or bone marrow responses (NIH and B10 strains having similar levels of eosinophil response in gut tissue) and was unrelated to the level of resistance to infection. Whereas NIH were highly resistant, with adult worm burdens at 13 days post-infection and muscle larval burdens at 35 days post-infection significantly lower than all other strains, B10 were quite susceptible, retaining substantial worm burdens at day 13 and harbouring large numbers of muscle larvae. Measurements of the level of the eosinophilopoietic cytokine IL-5 in sera during infection showed that the two strains differed in the kinetics of release but not in their absolute capacity to produce this cytokine. NIH mice released high levels during a primary infection, B10 released high levels during a secondary infection.(ABSTRACT TRUNCATED AT 250 WORDS)

Lysophospholipase activity of Ascaris suum-induced mouse peritoneal neutrophils and eosinophils

Lysophospholipase activity of mouse peritoneal neutrophils and eosinophils was studied to determine if neutrophils and eosinophils have lysophospholipase activity when treated with Ascaris suum whole worm extract, if zymosan activated complement can induce increased lysophospholipase activity, or if the immune status of the host has an effect on lysophospholipase activity. Neutrophils from noninfected or infected (immunized) mice were found to have increased lysophospholipase activity when treated with A. suum whole worm extract or zymosan activated complement demonstrating neutrophils as a source of lysophospholipase activity in the presence or absence of an immune response. Eosinophils from immunized mice had increased lysophospholipase activity when treated with either A. suum whole worm extract or zymosan activated complement.