What condition is characterized by a defective immune response due to insufficient white blood cells, particularly lymphocytes?

The condition characterized by a defective immune response due to insufficient white blood cells, especially lymphocytes, is immunodeficiency. This term encompasses a variety of disorders where the immune system's ability to fight infections and disease is compromised. A key aspect of immunodeficiency is that it can be either primary, resulting from genetic factors affecting lymphocyte production, or secondary, due to infections, medications, or other underlying health conditions.

In the context of medical conditions, immunodeficiency may occur when there are abnormally low levels of immune cells, which can lead to increased susceptibility to infections and certain cancers. The mention of lymphocytes is particularly important, as these cells play a critical role in the adaptive immune response, including the body's ability to remember and respond to pathogens.

The other options refer to different medical conditions: Gas gangrene is a type of tissue death caused by bacterial infection, Hodgkin's disease is a type of cancer that affects the lymphatic system, and hemorrhagic fever is a viral infection characterized by severe bleeding and other systemic symptoms. While these conditions can influence the immune system, they do not specifically denote the overarching issue of insufficient white blood cells leading to a compromised immune response, making immunodeficiency the most appropriate choice for the question regarding