Lamina Propria and GALT: Their Relationship with Different Gastrointestinal Diseases, Including Cancer

The structural integrity of the gastrointestinal tract is important because it dictates the functionality of this system. Regarding this, gut-associated lymphoid tissue (GALT) has a significant role in immunity. Most cancer research focuses on organized lymphoid structures and less on diffuse structures such as the lamina propria (LP). Therefore, this paper aims to investigate the link between the LP and cancer in humans. The interstitial matrix and loose connective tissue layer located directly under the epithelium is known as the LP. In this area, there are a lot of IgA+ plasma cells (PCs), T and B lymphocytes, macrophages, dendritic cells (DCs), and stromal cells (SCs). Antigens from the lumen are picked up by LP DCs and presented directly to B cells, which may cause IgA class switching and differentiation in the presence of T cells. In humans, the GALT of the mucosa has been proposed as the source of a unique malignancy known as “GALT carcinoma”, which is thought to represent the “third pathway of colorectal carcinogenesis”. However, present colorectal cancer classifications do not define GALT carcinoma as a separate histologic category.