Leucocyte proliferation in the bovine corpus luteum

Abstract

Leucocytes vary in type and number during the lifespan of a corpus luteum. The aim of this study was to determine whether there is an increase in the number of lymphocytes and macrophages as a result of local proliferation. Bovine corpora lutea were classified into stages of development, secretion and regression. A new double immunolabelling method was established for nuclear Ki-67 antigen (a marker for cell proliferation) and for leucocyte surface antigens (detection of CD2-, CD3-, CD4-, CD8-positive lymphocytes and CD14-positive monocytes). Differential cell counting was performed. Between the stages of development and regression there was an increase in the number of T-lymphocytes and macrophages. The percentage of proliferating leucocytes in relation to the total number of proliferating cells was approximately 20% at the stage of advanced secretion and 70% at late regression. The increase in the number of proliferating leucocytes at late regression was due to CD14-positive macrophages. These macrophages migrated from small blood vessels into the septa of corpora lutea at the early stage of regression. Macrophages showed local proliferation in the late stage of regression when capillaries were no longer present. It is concluded that the physiological involution of the corpus luteum is an inflammatory-like condition, which includes local proliferation of monocytes.

Rapid Accumulation of Polymorphonuclear Neutrophils in the Corpus luteum during Prostaglandin F2α-Induced Luteolysis in the Cow

“…Additionally, the CL regresses primarily through the loss of cells by apoptosis [14], [15]. These findings suggest that the luteolytic phenomenon is an inflammatory-like immune response [3], [4], [5].…”

“…During luteolysis, leukocytes, especially eosinophils, macrophages and T lymphocytes, are significantly increased in number, and 70% of all proliferating cells in the bovine CL are CD14-positive macrophages [5], [6]. Moreover, inflammatory cytokines such as tumor necrosis factor α (TNFα), interleukin 1β (IL-1β), and interferon γ (IFNγ), and chemokines such as monocyte chemoattractant protein-1 (MCP-1; recruitment of macrophages) are involved in luteal regression in cows [7], [8], [9], [10].…”

“…Various types of immune cells such as neutrophils, eosinophils, macrophages, and CD4-positive and CD8-positive T lymphocytes exist in the bovine CL and have essential roles in ovarian function [3], [4], [5]. During luteolysis, leukocytes, especially eosinophils, macrophages and T lymphocytes, are significantly increased in number, and 70% of all proliferating cells in the bovine CL are CD14-positive macrophages [5], [6].…”

Downregulation of Lymphatic Vessel Formation Factors in PGF_2α-induced Luteolysis in the Cow

“…During luteolysis, leukocytes, especially neutrophils, macrophages and T lymphocytes, significantly increase in number in the CL [10, 14, 21, 22, 50]. Pro-inflammatory cytokines such as TNFα, IL-1β and IFNγ and chemokines such as MCP1 and IL-8 are associated with luteal regression [3, 13, 14, 51, 52].…”

“…Leukocytes such as T lymphocytes, macrophages and neutrophils infiltrate the CL and produce different cytokines including tumor necrosis factor (TNF)-α, interleukin (IL)-1β, interferon (IFN)-γ and monocyte chemoattractant protein 1 (MCP1) during CL regression [10, 12,13,14,15,16,17,18,19,20,21, 22]. TNFα is secreted by activated macrophages and has been implicated in neutrophil and monocyte recruitment to inflammatory sites [23,24,25,26,27].…”