Leukocytes (white blood cells)
Leukocytes are nucleated, colourless cells that can change shape; a cubic millimetre of blood has about 6–8 thousand. They are made in red marrow, lymph nodes and other organs. I.I. Mechnikov discovered phagocytosis – leukocytes swallowing and digesting microbes. Redness, swelling and pus around a splinter show leukocytes fighting. Immunity is the body’s resistance to disease agents; lymphocytes make antibodies. Immunity is innate (inherited protection present from birth) or acquired: after illness or after vaccination; a baby also receives antibodies from the mother, but this protection is temporary. In vaccination a weakened, killed or harmless part of the disease agent is introduced so the body forms immune memory without getting the disease; vaccination schedules are set by doctors and are free in Uzbekistan. Ready antibodies (serum) are given by a doctor during illness. HIV is a virus that infects immune cells; it spreads through blood and other fluids (non-sterile instruments, mother to child), not through touch, shared food or handshakes. Modern treatment can keep the virus under control and allow a long, healthy life; testing and medical supervision are important.
“True/false” game on vaccination: write 6 statements (e.g. vaccination gives the body immune memory – true) and let a classmate answer. Reliable source: the clinic doctor.