Pathogens. Microscopic organisms that cause disease:virusesbacteriafungiparasitesEach attacks in a specific way . The Lymphatic System Protects us against disease . Lymphocytes:Lymphatic system cells respond to:environmental pathogenstoxinsabnormal body cells, such as cancers . What is the difference between nonspecific and specific defense, and the role of lymphocytes in the immune response?.