Answer:
The second-line defense associated with Crohn's disease and ulcerative colitis, both inflammatory bowel diseases (IBD), is immunosuppressive therapy. In cases where first-line treatments such as aminosalicylates or corticosteroids are insufficient, immunosuppressive medications are often prescribed. These medications, which may include azathioprine, mercaptopurine, methotrexate, or biologic agents like anti-TNF (tumor necrosis factor) drugs, help suppress the abnormal immune response in the gut, reducing inflammation and managing symptoms. The specific choice of immunosuppressive therapy depends on individual patient factors and disease severity.