to the bone

Laboratory flasks containing thousands of white blood cells from a patient who developed "immune tolerance" to the donor after a bone marrow transplant. The cells show no signs of rejection of the donor cells (three columns on the left), but secrete chemicals that indicate rejection (indicated in red) when exposed to the cells of a third person (three columns on the right). Source: Weizmann Institute magazine.

Education for tolerance

emphysema (emphysema). Illustration: shutterstock

Deep breath