[5] Owing to the absence of a histologically defined marginal sinus, the blood flowing in penicillar arterioles directly drains into capillaries of the red pulp and perifollicular zone.

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.

In addition, a large number of dendritic cells are thought to reside temporarily in the marginal zone before migrating into the white pulp following stimulation and antigen uptake, as well as a large number of lymphocytes remaining in the marginal zone for a period of time during the process of transmigration into the white pulp.

For example, the C-type lectin SIGN-R1 receptor (present on the marginal zone macrophages), mediates the recognition of pneumococcal saccharides and is necessary for Streptococcus pneumoniae clearance.

Evidence has shown that the clearance of lymphocytic choriomeningitis virus by marginal zone macrophages is crucial to prevent the spreading of viral infections to peripheral organs.