Deficient resistance by the body to disease. The defence system consists of two parts: white blood cells and proteins in the blood (antibodies). Immune deficiency can result from a shortage of either. White cell shortage or malfunction can occur in leukemia and Hodgkin’s disease. If only the antibodies are in short supply the condition is known as agammaglobulinae-mia. The general characteristic of immune deficiency is increased susceptibility to infection; a normally harmless virus or bacterium can cause dangerous illnesses such as severe pneumonia or meningitis. Treatment depends on the cause of the immune deficiency. Infection must be avoided as much as possible and, if it occurs, must be treated immediately with antibiotics.