Effects of stallion seminal plasma on hydrogen peroxide release by leukocytes exposed to spermatozoa and bacteria.

The article discusses how stallion seminal plasma affects a type of white blood cell’s response to the presence of sperm and bacteria. The study suggests stallion seminal plasma could serve a role in the reproductive system’s immune defence by assisting in the removal of excess sperm and bacteria.

Examining the Effects of Stallion Seminal Plasma on Phagocytosis

• The study experiments with the ability of stallion seminal plasma to alter the process of phagocytosis – where cells ingest harmful foreign particles like bacteria and dead or dying cells – especially in regards to the ingestion of spermatozoa (male reproductive cells) and specific bacteria, Streptococcus zooepidemicus.
• Phagocytosis is observed indirectly through the measurement of hydrogen peroxide (H2O2) produced by peripheral blood leukocytes, a type of white blood cell, after spermatozoa or bacteria are added. Hydrogen peroxide is a signal that phagocytosis is occurring as it is a byproduct of the process.

Seminal Plasma, Spermatozoa, and Leukocytes

• The research discovered that after adding ejaculated spermatozoa, hydrogen peroxide production was notably higher than after adding epididymal sperm (sperm from the epididymis, a part of the male reproductive system).
• Though when the epididymal sperm were pre-incubated with 6.25-50% seminal plasma, there was a dose-dependent increase in the subsequent hydrogen peroxide production by leukocytes. This suggests the presence of seminal plasma enhances the leukocyte’s response to the sperm cells.

Seminal Plasma and the Opsonization of Spermatozoa

• Apart from this, equine (horse) serum was found capable of opsonizing, or marking for ingestion by a leukocyte, both epididymal and ejaculated sperm. The process of opsonization aids in effective phagocytosis by binding to the surface of a particle and signaling to phagocytes that it should be ingested.
• Additionally, the seminal plasma directly stimulated the function of phagocytes: leukocytes that were pre-incubated with 12.5% or 25% seminal plasma released more hydrogen peroxide after the addition of S. zooepidemicus bacteria than the control leukocytes.

The Role of Seminal Plasma in Spermatozoa and Bacteria Clearance

• The study suggests that the opsonization of spermatozoa and the direct stimulation of phagocytes by the seminal plasma may represent mechanisms where the reproductive tract clears spermatozoa and bacteria.
• Effectively, stallion seminal plasma could play a role in maintaining cleanliness and preventing infection in the reproductive system by promoting the efficient removal of bacteria and excess sperm.