Bactericidal activity of peripheral blood neutrophils during the oestrous cycle and early pregnancy in the mare.

This research investigates the bactericidal activity of a type of white blood cell, neutrophils, during cycles of oestrus and early pregnancy in mares. This activity did not significantly differ across the oestrous cycle phases or during early pregnancy.

Oestrus Cycle Synchronization and Neutrophil Collection

• The study included 20 mixed-breed mares whose oestrous cycles were synchronized using daily injections of oestradiol-17 beta and progesterone for ten days. The hormones used are crucial in regulating the menstrual and oestrous cycles in mammals.
• On the tenth day, the mares were administered prostaglandin F-2 alpha to induce oestrus. Prostaglandin F-2 alpha is commonly used in veterinary medicine to control the timing of oestrus and ovulation.
• The researchers collected neutrophils, which are a type of white blood cell essential to the immune system’s first line of defense against pathogens. These cells were isolated from the mares’ jugular blood on the second or third day of oestrus, Days 5 and 7 post-ovulation, and during early pregnancy (Days 18-34 of pregnancy).

Examination of the Bactericidal Activity of Neutrophils

• The isolated neutrophils were challenged with Staphylococcus aureus, a common bacterial pathogen, to determine their bactericidal activity. The bactericidal activity refers to the ability of the neutrophils to kill bacteria, which is a crucial aspect of the body’s immune response.
• The researchers evaluated the bactericidal activity of the neutrophils after 30 and 120 minutes of incubation by measuring the reduction of colony forming units. These units are used to estimate the number of viable bacteria in a sample, allowing a quantitative evaluation of the neutrophils’ bactericidal activity.

Findings of the Study

• The bactericidal activity of the neutrophils increased with the time of incubation, indicating that the longer the neutrophils were allowed to interact with the bacteria, the more effective they were at killing them.
• The study found no significant difference in the bactericidal activity of the neutrophils during different phases of the oestrous cycle and early pregnancy. This suggests that the reproductive state of the mare does not impact the efficacy of these white blood cells in fighting off bacterial infections.