Interferon gamma (IFN-γ) is a dimerized soluble cytokine that is the only member of the type II class of interferons. The existence of this interferon, which early in its history was known as immune interferon, was described by E. F. Wheelock as a product of human leukocytes stimulated with phytohemagglutinin, and by others as a product of antigen-stimulated lymphocytes. It was also shown to be produced in human lymphocytes. or tuberculin-sensitized mouse peritoneal lymphocytes challenged with Mantoux test (PPD); the resulting supernatants were shown to inhibit growth of vesicular stomatitis virus. Those reports also contained the basic observation underlying the now widely employed IFN-γ release assay used to test for tuberculosis. In humans, the IFN-γ protein is encoded by the IFNG gene. Function
IFN-γ, or type II interferon, is a cytokine that is critical for innate and adaptive immunity against viral, some bacterial and protozoan infections. IFN-γ is an important activator of macrophages and inducer of major histocompatibility complex class II molecule expression. Aberrant IFN-γ expression is associated with a number of autoinflammatory and autoimmune diseases. The importance of IFN-γ in the immune system stems in part from its ability to inhibit viral replication directly, and most importantly from its immunostimulatory and immunomodulatory effects. IFN-γ is produced predominantly by natural killer cells (NK) and natural killer T cells (NKT) as part of the innate immune response, and by CD4 Th1 and CD8 cytotoxic T lymphocyte (CTL) effector T cells once antigen-specific immunity develops as part of the adaptive immune response.
Periodic breathing is clusters of breaths separated by intervals of apnea or near-apnea. As opposed to normal breathing which is usually regular, periodic breathing is defined as three or more episodes of central apnea lasting at least 4 seconds, separated by no more than 30 seconds of normal breathing.Periodic breathing was originally thought to arise from serious neurologic or cardiovascular disease and therefore to carry a poor outlook. It is now known that periodic breathing also tends to occur during sleep, it can occur in healthy persons, and the apnea in periodic breathing is usually central sleep apnea rather than obstructive sleep apnea. Periodic breathing during sleep occurs typically in adult patients with congestive heart failure. Periodic breathing is also a normal variation of breathing found in premature and full term infants. It occurs when the infant has pauses in breathing for no more than 10 seconds at a time followed by a series of rapid, shallow breaths. Then the breathing returns to normal without any stimulation or intervention. These pauses in breathing may be accompanied by minor oxygen desaturation and bradycardia. It usually occurs when the infant is sleeping deeply, but may occur with light sleep or even when awake. Studies have shown that 78% of healthy full-term infants experience episodes of periodic breathing in the first two weeks of life, which typically resolves in the first six months of life. == References ==