Ontogeny of lymphocyte function in the equine fetus.

This research examines how the immune system develops in pony fetuses, revealing that T lymphocytes are functional by the 100th day of gestation, B lymphocytes become functional by the 200th day, and that foals are capable of an immune response before birth.

Overview of Research

• The study investigates the development and functionality of different cells in the immune system within pony fetuses, especially focusing on T and B lymphocyte cells. The cells were obtained from thymus, liver, spleen, mesenteric lymph nodes, peripheral blood, and bone marrow during various stages of the fetuses’ gestation period up to 200 days old.

Methodology and Findings

• The research utilized in vitro phytolectin and allogeneic lymphocyte stimulation to analyze the functionality of these cells.
• The researchers found that phytolectin-responsive cells could be observed in the fetus’s thymus by day 80 of gestation, in peripheral blood by day 120, in lymph nodes by day 160, and in the spleen by day 200.
• In a similar way, cells that responded to mixed lymphocyte cultures could be found in the thymus by the 100th day of gestation and in the spleen by day 200.

Immunoglobulin Levels

• The researchers also measured levels of Immunoglobulin M and Immunoglobulin G (types of antibodies) in the fetus using a method called radioimmunoassay. These were detectable in fetuses prior to the 200th day of gestation.
• All 50 of the normal newborn foals had detectable levels of IgM. While quantities of IgG were generally lower and displayed greater variation, they were still present in the serum.

Conclusion

• The research concluded that T lymphocyte cells in the fetus become functional by the 100th day of gestation, and B lymphocyte cells become functional by the 200th day.
• This implies that foals are capable of mounting an immune response before they are born, showing their immune system development starts well in utero.