Unique characteristics of the intestinal immune system as an inductive site after antigen reencounter.

Background: Immunization prepares the body for a reencounter with the microbe. Information on the targeting of immune effector cells during secondary immune response--that is, lymphocyte homing--is scarce. In the present study, the homing potentials of lymphocytes are examined after antigen reencounter at mucosal versus nonmucosal sites.

Cutaneous lymphocyte antigen expression on human effector B cells depends on the site and on the nature of antigen encounter.

In contrast to T cells, information on skin-homing B cells expressing the cutaneous lymphocyte antigen (CLA) is sparse. CLA expression on human B cells was investigated among circulating immunoglobulin-secreting cells (ISC) and among antigen-specific antibody-secreting cells (ASC) elicited by parenteral, oral or rectal primary immunization, or by parenteral or oral secondary immunization with Salmonella typhi Ty21a. CLA expression was examined by combining cell sorting with an enzyme-linked immunospot assay.