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PubMed1976

In vitro effect of the lethal antibody on schistosomula in sera of rhesus monkeys immunized with highly x-irradiated cercariae.

The in vitro effect of the lethal antibody on schistosomula in sera of rhesus monkeys immunized with highly X-irradiated cercariae of Schistosoma mansoni or S. japonicum was studied. In all 6 experimental monkeys, 4 unchallenged and 2 challenged, the effects of lethal antibody on schistosomula were demonstrated. The sera of the challenged monkeys had no stronger lethal effect than those of the unchallenged monkeys. This shows that the lethal antibody can be produced by the antigenic stimulation of schistosomula alone. The mortality rates of schistosomula in immune sera were already high at day 1, increased to a certain extent from day 1 to day 4, but showed no significant further increase in days 5 and 6. Two kinds of immunological reactions were observed: perischistosomular precipitate (PSP) and perischistosomular envelope (PSE). Schistosomula surrounded with PSP were usually dying or dead and those enclosed in PSE were usually alive and motile. Thus PSP may be related with the lethal antibody and PSE with a kind of enhancing antibody. Schistosomula with PSP showed a positive fluorescent reaction when stained with fluorescein-labeled rabbit anti-rhesus IgG. Scanning electron micrographs of schistosomula with PSP showed a highly degenerated tegument. These facts indicate that the antibody in PSP contains a fraction of IgG which acts on the tegument of schistosomula.

Animals↗
PubMed1993

Pulmonary T helper lymphocytes are CD44hi, CD45RB- effector/memory cells in mice vaccinated with attenuated cercariae of Schistosoma mansoni.

Percutaneous exposure of C57Bl/6 strain mice to radiation-attenuated schistosome cercariae stimulates proliferation of Ag-specific T lymphocytes in the draining lymph nodes (LN), followed by an intense leukocytic infiltration into the pulmonary parenchyma and airways. The airway T cells persist at elevated levels at least up to 10 wk and will secrete IFN-gamma and IL-3 upon antigenic stimulation in vitro. We report here that more CD4+ T cells from the airways responded rapidly to mitogen by up-regulating the p55 subunit of the IL-2R than did splenocytes from the same animal, suggesting that the bulk of the pulmonary Th infiltrate comprised previously activated cells. A four-fold higher response to Ag indicated the greater abundance of schistosome-specific cells in the lungs than the spleen. Virtually all of the pulmonary CD4+ T cells expressed high levels of the memory marker CD44 (Pgp-1), in contrast with the situation in the draining LN and circulation where only a minority were in that category. Very few Th cells from the inflamed lung bound antibody to an epitope coded for by the B exon of CD45, unlike those from the LN and circulation; the antibody normally binds strongly to naive and weakly to memory CD4+ T cells. Overall, the airway CD4+ T lymphocytes in the schistosome-vaccinated mouse display the functional and phenotypic characteristics of short-term effector/memory cells. We believe that their presence endows the lung with the ability to respond rapidly to recall Ag in the form of challenge parasites.

Animals↗
PubMed1977

Stereoscan studies of cercariae, metacercariae, and adults of Cryptocotyle lingua (Creplin 1825) Fischoeder 1903 (Trematoda: Heterophyidae).

The cercaria of Cryptocotyle lingua has simple pointed spines all over the body. Four pointed modified spines occur dorsally in the mouth, and similar spines surround the openings of the penetration glands. The modified spines are shed shortly after penetration and encystment in the fish host. Less than a week after encystment, cytoplasmic folds develop all over the tegument. After about 4 weeks the cytoplasmic folds have disappeared and the spines are now flattened and serrated. The external surface of adults from herring gulls is very similar to that of mature metacercariae. It is provided with scalelike serrated spines which are especially well developed ventrally on the anterior end.

Animals↗