Opsonins of Streptococcus in uterine flushings of mares susceptible and resistant to endometritis: control of secretion and partial characterization.

The research investigates the release of opsonins, which help the immune system identify and attack harmful bacteria, in the uterus of mares that are either susceptible or resistant to endometritis, an inflammation of the uterus’s lining. The researchers found that all mares had increased opsonins following the introduction of a bacteria culture. However, the levels were higher in mares susceptible to endometritis during their estrus cycle, while those resistant had higher levels during the diestrus cycle.

Study Methods and Process

• The researchers explored the release of opsonins in the uterine lumen of mares that were either prone to endometritis or not, following an inoculation of a filtrate of Streptococcus culture fluid.
• They collected uterine flushing samples before and at several intervals up to 24 hours after inoculation, specifically on the 2nd or 3rd day of estrus and on the 7th or 8th day following ovulation.
• The amounts of opsonins in these flushing samples were then measured by comparing the production of H2O2 (Hydrogen Peroxide) by leukocytes in the presence of opsonized and non-opsonized bacteria.

Findings of the Study

• In all mares studied, there was an increase in opsonin levels after inoculating with the Streptococcus culture fluid.
• There were notable differences relating to the estrus cycle. For mares with resistance to endometritis, opsonin levels were higher during the diestrus stage than estrus. The opposite was found in mares susceptible to endometritis.
• There was a higher overall level of opsonins in the uterine flushings of mares susceptible to endometritis compared to those resistant to the condition, but this contrast was only observable during the estrus phase.

Initial Characterization of Opsonins

• A preliminary characterization of the opsonins found in uterine secretions was carried out, utilizing ammonium sulfate fractionation and gel filtration methods.
• This indicated that the opsonins were primarily associated with fractions of high molecular weight that were soluble in ammonium sulfate, and an ammonium sulfate-precipitable fraction linked to immunoglobulin G.