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 OPEC wants to raise the price of crude oil, it simply reduces production. This causes gasoline prices to jump because of the short supply, but also because of the possibility of future reductions. When oil production dips, gas companies get nervous. The mere threat of oil reductions can raise gas prices.