Marginal zone

The marginal zone is the region at the interface between the non-lymphoid red pulp and the lymphoid white-pulp of the spleen. (Some sources consider it to be the part of red pulp which borders on the white pulp, while other sources consider it to be neither red pulp nor white pulp.)

A marginal zone also exists in lymph nodes.

Composition and markers
It is composed of cells derived primarily from the myeloid compartment of bone marrow differentiation. At least three distinct cellular markers can be used to identify cells of the marginal zone, MOMA-1, ERTR-9 and MARCO.

Function
The major role of marginal zone is to trap particulate antigen from the circulation and present the antigen to the lymphocytes of the spleen.

Experiments have shown that inert latex beads as well as live bacteria such as Escherichia coli and Listeria monocytogenes are trapped by the marginal zone. However, only immunogenic substances, i.e. bacteria, are trafficked to the T and B cell zones of the white-pulp and are efficiently presented to elicit an immune response.

Lymphocytes
Marginal zone lymphocytes are a type of B cell (Marginal-zone B cell, abbreviated "MZ B cell") created there, capable of binding IgM-antigen complexes. They are notable for their ability to serve several different roles in the immune system.