It is known that blood is a functionally very loaded element of the body. Therefore, it seems natural that the farther, the more different blood tests appear, allowing you to diagnose a disease. So, recently it was reported about the appearance of a blood test, which can be used to diagnose Alzheimer’s disease before the onset of symptoms. That analysis revealed a lack of certain metabolites in the blood, which was a signal of Alzheimer’s disease.
An article published in one of the leading scientific journals PNAS, we are talking about a blood test that allows you to diagnose asthma in humans.
Asthma is a disease characterized by chronic inflammation of the respiratory tract, in which a person has asthma, shortness of breath, cough. Currently, there are more than 300 million patients with this disease in the world.
There are a number of tests aimed at diagnosing the disease, such as spirography or peak fluometry. However, most of them are aimed at assessing the functional state of the lungs and bronchi – for example, they determine the volume and rate of inhaled air, its chemical composition. A significant disadvantage of these methods is their indirection. They do not allow to diagnose the disease “directly.” An additional disadvantage is that such tests work if the symptoms of asthma occur in a person at the time of the visit to the doctor.
Thus, the question of the invention of a quality test that can detect bronchial asthma is more than relevant.
This is where the blood multifunctionality comes to the fore. The process of any inflammation is associated with an increase in the number of immune cells of a certain type in the blood – neutrophils. These cells, circulating in the bloodstream, are able to leave the blood vessel and migrate to the site of infection in order to “swallow” and “digest” the bacteria or those cells that have become infected (this process is called phagocytosis).
How does a neutrophil find out where the inflammation is in the tissue? For this there is a special mechanism of chemotaxis. Neutrophil is able to sense special chemical signals – substances that are formed during inflammation. Thus, perceiving these signals, he, like a bloodhound dog, moves along the gradient of these substances, that is, where their concentration is as high as possible.
The method of diagnosing bronchial asthma, proposed by specialists from the University of Wisconsin (Madison, USA), is based on testing the function of neutrophil chemotaxis.
The method was named by the authors of KOALA (kit-on-a-lid-assay). At its core, it is quite simple and somewhat reminiscent of running sports. In a specially designed small chamber, only neutrophils are released from a drop of blood, which takes no more than 5 minutes. At the next stage, the neutrophils begin to migrate with the help of chemotaxis along the paths of a chemoattractant applied to the surface – a substance that serves as a “bait” for a neutrophil. Further, using special software on a computer, the neutrophil migration rates are analyzed.
Using the described method, the authors conducted a study of 34 patients in which they reliably managed to distinguish patients with asthma from patients with another inflammatory disease, allergic rhinitis (“hay fever”).
The study reliably showed a reduced neutrophil migration rate in patients with asthma. It is this characteristic that may in the future prove to be a marker in the diagnosis of this disease.
It is clear that for the introduction of such a test into the ubiquitous practice, it is still necessary to conduct a statistical study of a large number of patients, however, its great advantages are already visible: simplicity – only a small amount of blood is needed, the analysis itself is not very long; low cost – the camera is made of pieces of ordinary plastic; accuracy – analysis is performed at the cellular level.