Effects of neutrophils in rat luteal cells

Ovarian function may be modulated by cells of the immune system. We have investigated the role of neutrophils (polymorphonuclear leukocytes) on rat luteal cell function. Activated neutrophils inhibited LH-sensitive cAMP accumulation, which was dependent on neutrophil cell number. At a concentration of 10(6) neutrophils/ml and 10(5) luteal cells/ml, LH-stimulated cAMP accumulation was inhibited by 50%. The inhibitory effect of activated neutrophils was reversed by superoxide dismutase (SOD) and catalase. LH-stimulated progesterone production was also inhibited by activated neutrophils. Progesterone production by 10(5) luteal cells was inhibited approximately 20% in the presence of 10(6) activated neutrophils, and this inhibition was blocked by SOD and catalase. Conditioned medium from activated neutrophils also produced inhibitory effects on LH-stimulated cAMP accumulation and progesterone production, which could be reversed by SOD and catalase. The phosphodiesterase inhibitor isobutylmethylxanthine had no significant effect on the inhibition of cAMP accumulation by conditioned medium from activated neutrophils. Luteal cells loaded with a fluorescent indicator for determining intracellular reactive oxygen species (dichlorofluorescein diacetate) showed increased fluorescence in the presence of activated neutrophils. No increase in fluorescence occurred in the absence of neutrophils or in the presence of SOD and catalase. These studies demonstrate that reactive oxygen species produced by activated neutrophils can enter the luteal cell and cause antigonadotropic effects. Although the experimental model used in the present studies may not be truly physiological, the data demonstrate that neutrophils may play a role in functional and structural regression of the corpus luteum in the rat.