Title: Mucosa-associated lymphoid tissue
Content:  The mucosa-associated lymphoid tissue (MALT), also called mucosa-associated lymphatic tissue, is a diffuse system of small concentrations of lymphoid tissue found in various submucosal membrane sites of the body, such as the gastrointestinal tract, nasopharynx, thyroid, breast, lung, salivary glands, eye, and skin. MALT is populated by lymphocytes such as T cells and B cells, as well as plasma cells and macrophages, each of which is well situated to encounter antigens passing through the mucosal epithelium. In the case of intestinal MALT, M cells are also present, which sample antigen from the lumen and deliver it to the lymphoid tissue. MALT constitute about 50% of the lymphoid tissue in human body. Immune responses that occur at mucous membranes are studied by mucosal immunology.
Title: Mucosa-associated lymphoid tissue
Content:  MALT plays a role in regulating mucosal immunity. It may be the site of lymphomas, usually a non-Hodgkin lymphoma. A specific entity is the marginal zone B-cell lymphoma (a subtype of which is termed MALT lymphoma). Certain subtypes of marginal zone B cell lymphomas such as those occurring in the stomach are commonly caused by Helicobacter pylori infection. Peyer's Patches, groupings of lymphoid follicles in the mucus membrane, monitor the GALT closely to regulate pathogens that traverse through the area. Due to function of M cells in Peyer's Patches, adherence and transport of antigens across a single layer of epithelial cells, it's likely that dysfunction in these structures allow and entry point to pathogens.
Title: Mucosal immunology
Content:  without a large and unnecessary systemic immune response. Since the mucosal membranes are the primary contact point between a host and its environment, a large amount of secondary lymphoid tissue is found here. The mucosa-associated lymphoid tissue, or MALT, provides the organism with an important first line of defense. Along with the spleen and lymph nodes, the tonsils and MALT are also considered to be secondary lymphoid tissue. The mucosal immune system provides three main functions:  At birth, the neonate's mucosal immune system is relatively undeveloped, but the colonization of intestinal flora promotes its development. Because of its front-line status within the immune system, the mucosal immune system is being investigated for use in vaccines for various afflictions, including AIDS   and allergies.
Title: Mucosa-associated lymphoid tissue
Content: GALT (gut-associated lymphoid tissue. Peyer's patches are a component of GALT found in the lining of the small intestines.) ; BALT (bronchus-associated lymphoid tissue) ; NALT (nasal-associated lymphoid tissue) ; CALT (conjunctival-associated lymphoid tissue) ; LALT (larynx-associated lymphoid tissue) ; SALT (skin-associated lymphoid tissue) ; VALT (vulvo-vaginal-associated lymphoid tissue) ; TALT (testis-associated lymphoid tissue) O-MALT (organized mucosa-associated lymphatic tissue); specifically, the tonsils of Waldeyer's tonsillar ring are O-MALT. ; D-MALT (diffuse mucosa-associated lymphatic tissue); MALT that is not organized as a separately macroscopically anatomically identifiable mass, tissue or organ (such as the aforementioned O-MALT) is diffuse MALT. The components of MALT are sometimes subdivided into the following: It can be also distinguished by level of organization of the tissue:
Title: Gut-associated lymphoid tissue
Content:  Gut-associated lymphoid tissue (GALT) is a component of the mucosa-associated lymphoid tissue (MALT) which works in the immune system to protect the body from invasion in the gut. Owing to its physiological function in food absorption, the mucosal surface is thin and acts as a permeable barrier to the interior of the body. Equally, its fragility and permeability creates vulnerability to infection and, in fact, the vast majority of the infectious agents invading the human body use this route. The functional importance of GALT in body's defense relies on its large population of plasma cells, which are antibody producers, whose number exceeds the number of plasma cells in spleen, lymph nodes and bone marrow combined. GALT makes up about 70% of the immune system by weight; compromised GALT may significantly affect the strength of the immune system as a whole.
Title: Waldeyer's tonsillar ring
Content:  There also normally is a good amount of mucosa-associated lymphoid tissue (MALT) present between all these tonsils (intertonsillar) around the ring, and more of this lymphoid tissue can variably be found more or less throughout at least the naso- and oropharynx.
Title: MALT lymphoma
Content:  MALT lymphoma (MALToma) is a form of lymphoma involving the mucosa-associated lymphoid tissue (MALT), frequently of the stomach, but virtually any mucosal site can be afflicted. It is a cancer originating from B cells in the marginal zone of the MALT, and is also called extranodal marginal zone B cell lymphoma.
Title: Mucosal associated invariant T cell
Content:  human MAIT cell populations. In healthy humans, MAIT cells are found in the lungs, liver, joints, blood, and mucosal tissues, such as the intestinal mucosa. In total, MAIT cells make up roughly 5% of the peripheral T cell population. MAIT cells are most common in the liver, where they usually comprise 20-40% of the T lymphocyte population. The total murine MAIT cell population is roughly ten times smaller than the human MAIT cell population. While MAIT cells display effector characteristics immediately out of the thymus, they may also undergo clonal expansion in the periphery and establish antigen memory. In this way, MAIT cells display both innate and adaptive characteristics.
Title: Marginal zone B-cell lymphoma
Content:  Marginal zone B-cell lymphomas, also known as marginal zone lymphomas (MZLs), are a heterogeneous group of lymphomas that derive from the malignant transformation of marginal zone B-cells. Marginal zone B cells are innate lymphoid cells that normally function by rapidly mounting IgM antibody immune responses to antigens such as those presented by infectious agents and damaged tissues. They are lymphocytes of the B-cell line that originate and mature in secondary lymphoid follicles and then move to the marginal zones of mucosa-associated lymphoid tissue (i.e. MALT), the spleen, or lymph nodes. Mucosa-associated lymphoid tissue is a diffuse system of small concentrations of lymphoid tissue found in various submucosal membrane sites of the body such as the gastrointestinal tract, mouth, nasal cavity, pharynx, thyroid gland, breast, lung, salivary glands, 
Title: Gut-associated lymphoid tissue
Content: Waldeyer's tonsillar ring ; Small lymphoid aggregates in the esophagus ; Lymphoid tissue accumulating with age in the stomach ; Peyer's patches in the small intestine ; Diffusely distributed lymphoid cells and plasma cells in the lamina propria of the gut ; Intraepithelial lymphocytes (IELs) interspersed into epithelial layer of mucosal surfaces ; Lymphoid aggregates in the appendix and large intestine ; Mesenteric lymph nodes draining lymph coming from the gut tissue The gut-associated lymphoid tissue lies throughout the intestine, covering an area of approximately 260–300 m2. In order to increase the surface area for absorption, the intestinal mucosa is made up of 

Question: where are mucosal associated lymphoid tissues present in the human body and why?
Answer: oral passage.
salivary glands.
gastrointestinal tract.
breast.
skin.
thyroid.
lung.
nasopharyngeal tract.
eye.