Evidence for the involvement of a bone marrow-derived cell population in the immune expulsion of Trichinella spiralis

Resistance against Trichinella spiralis infection in pups delivered by T. spiralis-infected dam

Maternal antibody transmission via placenta and breastmilk are known to confer protection in infants. In this study, we investigated the maternal immunity transmission in pups delivered by rats infected with Trichinella spiralis and assessed the resulting resistance against subsequent parasitic infection. Our results revealed that parasite-specific IgG, IgG1 and IgG2a antibodies were present in pups prior to breastmilk ingestion (pre-milk), in which IgG and IgG1 antibodies persisted until week 8 after birth while parasite-specific IgG2a antibodies only lasted until week 4. After weaning on week 3, pups delivered by T. spiralis-infected dam and subsequently challenge-infected (immune-challenge) were found to possess higher mucosal IgG antibodies than control groups, whereas mucosal IgA levels were not significantly different across all groups. T. spiralis excretory-secretory antigen was discovered to react with pup sera until week 8, correlating with the resistance against parasitic infection which is represented by lessened worm burden. Upon T. spiralis infection at weeks 3 and 8, lower levels of eosinophil responses were detected in immune-challenge pups compared to naïve-challenge pups, indicating correlates of resistances in which ADCC may be involved. Findings from the present study demonstrate that resistances against T. spiralis infection in pups can be acquired by maternally-derived IgG, IgG1 and IgG2a antibody transmission through the placenta and breastmilk from T. spiralis-infected dam, which lasts until week 8.

Pathways of murine mast cell development and trafficking: tracking the roots and routes of the mast cell

The appreciation of the role of the mast cell (MC) in inflammatory processes has expanded dramatically during the last decade. Many of these processes, especially more prolonged responses, are accompanied by an increase in the number of MCs, and much of this increase is likely because of recruitment of immature progenitors with subsequent maturation under the control of the tissue microenvironment. We have begun to identify many of the cell-surface molecules that control this influx and have traced the development of these cells back to their hematopoietic roots. This development proceeds along the myelomonocytic pathway with distinct intermediates having been identified in both bone marrow and spleen. The expression of alpha4beta7 integrins has played a prominent role in this process, as it helped identify a bipotent basophil MC precursor in the spleens of C57BL/6 mice. This integrin also controls basal influx into the intestine and, along with alpha4beta1 integrins, plays a critical role in recruitment to inflamed lungs. Investigation of chemokines and chemokine receptors in these processes led to the identification of a dual role for the murine interleukin-8 receptor CXCR2. This alpha-chemokine receptor affects MC progenitor trafficking by its expression by MC progenitors and by its expression on stromal cells, likely endothelium, affecting trafficking to both intestine under basal conditions and lung during inflammatory recruitment.

Host-parasite interactions in rodent nematode infections

In rodents, Trichinella spiralis and Nippostrongylus brasiliensis infect the small intestine and Trichuris muris resides in the colon. The intestinal host response in these animals is characterized by changes in mucosal architecture and inflammation and is associated with worm expulsion. The requirement of T cell-mediated host response in worm expulsion has been demonstrated over many years. Subsequent studies have shown that Th2-type, but not Th1-type, responses mediate resistance to the nematodes. Investigations using neutralizing antibodies and genetically manipulated mice have characterized the contribution of individual Th2-type cytokines in not only worm expulsion, but also specific cellular changes that occur in the mucosa, such as alterations in epithelial phenotype and smooth muscle. There is also increasing appreciation of the contribution of non-bone marrow-derived cells in innate and adaptive host responses in these models.

Characterization of the thoracic duct T-helper cells that co-mediate, with antibody, the rapid expulsion of Trichinella spiralis in adult rats

Thoracic duct cells that act synergistically with immune serum or antibody to transfer rapid expulsion of a challenge infection with Trichinella spiralis muscle larvae were characterized as OX38+, OX8-, OX22- T helper cells. Protective capacity was confined to the dividing T helpers that appeared on days 3-5 in the thoracic duct of rats during a T. spiralis infection. To realize their intestinal priming potential in recipient rats. MHC-compatibility between donor and recipient rat was required. Fractionation of immune serum with 40% saturated ammonium sulphate left transferable protective activity in both the precipitate and supernatant fractions. Absorption of immune serum with muscle larvae antigen removed the capacity to transfer protection.

Studies on experimental ancylostomiasis: transfer of acquired immunity to Ancylostoma caninum in mice through sensitized thymus and bone marrow cells

An attempt has been made to transfer acquired immunity to Ancylostoma caninum infective larvae from infected Swiss albino female mice to nonimmune, isologous recipients of same sex, through immunized thymus and bone marrow cells. Immunized cells from donors infected with a single high dose of 1000 larvae were found to be more immunocompetent than cells from donors infected with a single, but low dose of 500 larvae.

Transplantation of adult Trichinella spiralis between hosts: worm survival and immunological characteristics of the host--parasite relationship

A technique for the transplantation of Trichinella spiralis worms directly into the host intestine is described. Infections established by the direct transfer of adult worms were essentially normal both in terms of their survival and reproduction and in their stimulation of, and susceptibility to, host immune responses. Worms transplanted from NIH mouse donors at intervals after infection had an equal ability to survive in the recipient, even when taken from the donor shortly before or during the process of worm expulsion, showing that expulsion does not require worms to be irreversibly damaged. It was noted, however, that after 7 days in the donor the ability of the worm to reproduce in the recipient was temporarily impaired.

Immunity to intestinal parasites

Intestinal parasites are common in man and animals and can cause severe disease. Knowledge of immunity to such infections is limited and comes largely from studies using laboratory host-parasite systems. Understanding how immunity can operate, and why it often does not, is not only of intrinsic interest but necessary for the development of immunological methods of control.

Transfer of immunity to Trichinella spiralis in the mouse with mesenteric lymph node cells: time of appearance of effective cells in donors and expression of immunity in recipients

Cells capable of transferring immunity to Trichinella spiralis, i.e. of accelerating adult worm expulsion, were present in the mesenteric lymph nodes of mice infected for 4, 6 or 8 days, but not in mice infected for only 2 days. The time-course of worm expulsion in mice infected on the day of transfer was similar in recipients of day 4 or day 8 cells, expulsion becoming marked only when the recipients had been infected for at least 6 days. Transfer of cells 4 or 6 days after infection did not result in an accelerated worm expulsion; transfer 1 or 2 weeks before infection did not enhance the level of immunity in recipient mice. In contrast to the results obtained with mesenteric lymph node cells (MLNC) on immunity was transferred when recipients were given spleen cells taken from donors infected for 8 days. It is suggested that MLNC do not cause worm expulsion directly, but cooperate with another component of the host's defence mechanism. Accelerated expulsion in recipients of cells was accompanied by a premature decline in fecundity of female worms. Evidence is presented to show that worm expulsion and impaired reproduction may represent independent aspects of the immune response to T. spiralis.