Unification of foetal and neonatal immunology

Canine fetus immune system at late development

The immune system is mainly responsible for protecting the organism against agents that may interfere in its homeostasis. Thus, understand how this system develops and operates is very important, for create new therapies to assist this system in its operation, such as its failure. In domestic dogs, few studies show how actually occurs the development, maturation and functioning of the immune system. Therefore, this study demonstrates the development and possible activation of it on dog fetus from late gestational period by in situ and microscopic analyzes.

Functional development of immune response in rabbits

The aim of our study was to extend knowledge concerning postnatal development of the immune system in rabbits from two aspects. Firstly, capability of lymphocytes from peripheral blood, spleen, mesenteric, and popliteal lymph nodes to respond to Concanavalin A stimulation was investigated. Secondly, changes in the ability to produce antibodies against tetanus toxoid by rabbits during maturation were studied. Proliferation of lymphocytes was reduced in mesenteric lymph nodes in newborns, in PB up to the age of two weeks, and in popliteal lymph nodes up to the age of four weeks when compared to adults. High spontaneous lymphocyte proliferation that lasted up to the age of two weeks was recorded in spleen. The study of antibody response showed that even one-day-old rabbits were able to form specific antibodies of isotype IgM and IgG. Nevertheless, significantly lower formation of both isotypes was noted in one-day and two-week-old rabbits, and commencement of IgG isotype formation was delayed in one-day, two-week, and four-week-old rabbits when compared to adults.

Serum immunoglobulin G levels are positively related to reproductive performance in a long-lived seabird, the common tern (Sterna hirundo)

The evolution of longevity requires a low risk of mortality from extrinsic factors, relative to intrinsic factors, so that individuals that differentially invest in physiological self-maintenance and minimize their annual reproductive costs will maximize lifetime fitness through a prolonged reproductive lifespan. The trade-off between reproductive effort and self-maintenance, as measured by immune function, has been well documented in short-lived birds, but is difficult to demonstrate in long-lived birds. To assess self-maintenance in a long-lived seabird, we measured serum protein levels, including immunoglobulin G (IgG = IgY), in 30 breeding pairs of common terns (Sterna hirundo) and their first-hatched (A) chicks. Most parents were of known age from banding as hatchlings; our sample was selected to contrast young breeders (6-9 years) with very old birds (17-23 years). Body-mass of the parents declined by 5% during the chick-rearing period, while serum protein levels were stable. Serum IgG levels were higher in parents of offspring with faster growth rates, while IgG levels were lower in parents whose broods were reduced by starvation. A-chicks in broods of two had higher IgG levels than singleton chicks. Albumin levels were not related to reproductive performance. Thus, despite adequate statistical power, we could find no evidence for a trade-off between reproduction and self-maintenance in common terns, even in old age. The results are consistent with life-history predictions for long-lived vertebrates, in which selection favors sustained self-maintenance across the reproductive lifespan. The positive relationships between IgG levels and reproductive performance indicate that IgG can be used as an index of parental "quality."

In utero hematopoietic stem cell transplantation with haploidentical donor adult bone marrow in a canine model

OBJECTIVE

Chimerism can be achieved in a canine model of in utero bone marrow transplantation with > or =1 x 10(8) CD34(+) haploidentical donor cells per kilogram without graft-versus-host disease.

STUDY DESIGN

In utero bone marrow transplantation was performed by ultrasound-guided intraperitoneal infusion in 30- to 41-day-old canines with CD34(+) selected cells from paternal bone marrow at doses of 1.3 x 10(8) to 2.5 x 10(10) CD34(+) cells/kg. A method for marking control littermates was developed with intraperitoneal ethiodol. Postnatal studies included histologic, fluorescent in situ hybridization canine Y probe, and polymerase chain reaction-based chimerism analyses.

RESULTS

Term survival was 86% to 100% for transplantations > or =34 days versus 14% and 43% at 30 and 31 days. Microchimerism (<1%) was demonstrated in tissues from 4 informative litters that included thymus, liver, skin, spleen, and intestine. Neither gestational age nor donor CD34 cell dosage altered the level of engraftment in these experiments. There was no evidence of graft-versus-host disease.

CONCLUSION

In utero bone marrow transplantation in a canine model achieves microchimerism with high CD34(+) cell doses.

Lack of evidence for complement-dependent cytotoxic antibodies to fetal paternally derived antigens in the marsupial Macropus eugenii (tammar wallaby)

A total of 241 serum samples from 145 parous tammar wallabies (Macropus eugenii) were screened for presence of antibodies to paternally derived antigens of the fetus. These samples were taken at different stages in late pregnancy after placental contact was intimate and after birth. Complement-dependent cytotoxicity tests were unable to detect any specific antibodies. It is concluded that the yolk sac placenta of M. eugenii does not allow intimate enough contact between fetal tissues and the maternal circulation to induce formation of cytotoxic antibodies by its mother. This is in contrast to eutherian mammals, in which such production of cytotoxic antibodies occurs frequently as a result of pregnancy. Together with other data it is suggested that the short implantation period in M. eugenii, which is common to all marsupials, has probably not evolved to prevent maternal immune attack upon the conceptus.