Neutrophils are the most common type of white blood cell, comprising about 50-70% of all white blood cells. They are phagocytic, meaning that they can ingest other cells, though they do not survive the act. Neutrophils are the first immune cells to arrive at a site of infection, through a process known as chemotaxis.
One of the basic theories stipulates that increasing interest rates raise consumers' and manufacturers' costs, which, in turn, reduces the amount of time and money people spend driving. Less people on the road translates to less demand for oil, which can cause oil prices to drop.
When crude oil prices go up or down, gas prices tend to follow. And right now, oil prices are on the decline. Oil prices have been falling for several reasons, including the increased U.S. crude production and an outlook for weaker growth in global oil demand. Meanwhile, the Organization of the Petroleum Exporting Countries, or OPEC, decided toward the end of 2014 not to manipulate prices by restricting oil production.