Studies on immune responses in afferent and efferent lymph of lymph nodes draining the tissues have contributed to the concept that primary immune responses are generated in the lymph nodes with a delay before antigen-specific effector cells arrive at the affected tissue.
Lightning strikes the ground approximately 25 million times each year in the U.S. According to the NWS, the chance of an individual in the U.S. being killed or injured during a given year is one in 240,000. Assuming an average life-span of 80 years, a person's odds over their lifetime becomes one in 3000.
(I ask everyone who believes that the United States has God on its side to consider the theological implications of lightning striking the Mall on the 4th of July.) The NOAA website says that 400 people a year get struck by lightning, but doesn't make it clear whether that's worldwide or nationwide. Between 1997 and 2006, 437 people in the United States died from lightning strikes. Wyoming is the most dangerous state for lightning, and no one died of lightning strikes in Alaska, Delaware, D.C., Hawaii, New Hampshire or Washington state.