Final answer:
The statement is true; HIV targets and destroys specific white blood cells, which leads to a weakened immune system and increased risk of illness in affected individuals.
Step-by-step explanation:
The statement that a decrease in leukocytes can occur because some pathogens, such as HIV, destroy white blood cells (WBCs) is true. When HIV infects the body, it specifically targets certain white blood cells called CD4+ T cells, which are a critical part of the immune system. As HIV destroys these cells, the body's ability to fight off other pathogens like bacteria and viruses is compromised, leading to a condition known as leukopenia. If leukopenia is pronounced, individuals may become unable to ward off disease effectively. Conversely, a condition called leukocytosis occurs when there is excessive leukocyte proliferation; however, these cells can often be nonfunctional and may not effectively protect the body against disease either.