The immune system recognizes and destroys substances that contain antigens. Your body's cells have proteins that are antigens. These include a group of antigens called HLA antigens. Your immune system learns to see these antigens as normal and usually does not react against them.
Mother's Day 2016. Need to know the exact date of Mothers Day this year? Here's a chart that shows what day Mother's Day is celebrated from 2014 - 2021. In the US, Mother's Day is celebrated on the second Sunday in May. In the UK, mothers are honored the fourth Sunday of Lent. Check out our fun Mother's Day Games and Activities for teachers!
How Did Mother's Day Start? For more than 100 years, the second Sunday in May has traditionally been celebrated as Motherâs Day. Moms all over the world can look forward to hand-drawn cards, flowers, and perhaps even breakfast in bed. How did Motherâs Day start, anyway? Its history and controversies may surprise you.