As recently reported, extracts from macrocysts of Sarcocystis gigantea obtained by sonication show mitogenic activity towards lymphocytes. By affinity chromatography using a galactose gel, a lectin fraction which contained the entire mitogenic activity was obtained from these extracts.

The mitogenicity of extracts from Sarcocystis gigantea macrocysts is due to lectin(s).

Sarcocystis gigantea extract (SGE) was separated by affinity chromatography into one lectin-containing fraction (SGL) that was mitogenic to mononuclear cells (MNC) and another that lacked this lectin activity. The SGL-depleted Sarcocystis extract (SGTF) contained the so-called Sarcotoxin, inducing only a slight increase in MNC proliferation. Furthermore, preincubation of MNC with SGTF for 60 min suppressed the mitogenic capacity of SGL by 60%-90%. The results presented indicate that SGTF interacts with human MNC differently than SGL, particularly by interfering with the mitogenic lectin. These findings suggest that SGL and SGTF may be involved in different immunomechanisms induced by the parasite.

Interactions between Sarcocystis gigantea lectin and toxin-containing fractions in human lymphocyte cultures.

The present study further examined the in vitro response of human mononuclear cells (MNC) to theSarcocystis gigantea lectin (SGL). The results confirm our previous report that SGL is mitogenic for human MNC. We now report that SGL is not only a potent mitogen but also a polyclonal activator for human peripheral B cells. As was true for pokeweed mitogen (PWM, 2 μg/ml), the addition of SGL (25 μg protein/ml) to cultures of MNC caused lymphocyte proliferation and B-cell maturation, indicated by a marked increase in IgG and IgM production. As measured by the [3H]-thymidine incorporation assay, SGL induced significantly higher proliferative responses than PWM (P<0.01,n=24). The values obtained by SGL and PWM for IgG and IgM synthesis were essentially identical. As opposed to SGL, the sarcotoxin-containing fraction (SGTF) did not induce antibody formation or proliferative responses in human MNC.

Sarcocystis gigantea lectin--mitogen and polyclonal B-cell activator.

The invention provides vaccines and methods for preventing or treating intestinal protozoal infections in an animal. In particular, vaccines and methods for prevention or treatment of giardiasis are provided. The invention also encompasses methods of preparing and methods of use of novel toxins, antibodies, vaccine strains and compositions that result from or are used in these methods.

Giardia treatment and antibody

Basic fibroblast growth factor (bFGF) is a mitogenic polypeptide highly conserved between species, implicated in regenerative processes and present in all tissues examined. In the heart, bFGF is localized in association with nuclei, extracellular matrix and intercalated discs of cardiomyocytes. In this article is reported bFGF association with the intramuscular parasitic protozoan Sarcocystis in situ, in bovine hearts, detected by indirect immunofluorescence. Parasitic cysts appear connected directly to specialized host cell junctions: bFGF provides structural continuity between parasitic cyst wall and myocyte intercalated discs. Other proteins associated with intercalated discs such as desmin or desmoplakin are not detected in the cysts. Association with Sarcocystis suggests a new role for bFGF in the context of parasitic invasion and establishment.

A potential new role for bFGF in host-parasite interactions.

Extracts were prepared from macrocysts of Sarcocystis gigantea, an animal parasite, by sonication and high speed centrifugation. Mononuclear cells were obtained from the blood of 14 adults and 5 newborns and used for transformation assays. Addition of Sarcocystis extracts (equivalent to 400 micrograms protein/ml) to these cells increased the lymphocyte proliferation approximately 71 fold over the background. The control with Pokeweed mitogen (5 micrograms/ml) gave a stimulation index of 58. There was no difference in the response to the Sarcocystis extract between the lymphocytes of adults and those of newborns. This findings show that the effect of the extract is mitogenic and not due an anamnestic reaction.

Tietz Hj

Papers

Extracts from Sarcocystis gigantea macrocysts are mitogenic for human blood lymphocytes.

Interactions between Sarcocystis gigantea lectin and toxin-containing fractions in human lymphocyte cultures.