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Distribution and functional characteristics of antigen-specific helper T cells arising after Peyer's patch immunization.

Antigen-specific T-helper cells for IgA responses arise in Peyer's patches (PP) following their immunization by subserosal injection of keyhole limpet haemocyanin (KLH). These are of the W3/25 phenotype and the W3/25 receptor is shown here to be involved in their helper function. These cells originate in PP and migrate via mesenteric lymph nodes (MLN) to thoracic duct lymph, although the MLN appear to be unnecessary for the induction or maturation of antigen-specific helper cells collected in thoracic duct lymph after intra-Peyer's patch (i.p.p.) immunization. KLH-specific helper cells can be detected subsequently in the intraepithelial lymphocyte population and also among lamina propria lymphocytes. The helper cells also relocate to PP distant to their site of origin where they are retained only when antigen is present. While i.p.p. immunization is an efficient route for the induction of IgA helper cells in gut-associated lymphoid tissue, it differs from oral immunization in that concomitant induction of antigen-specific splenic suppressor cells does not occur, indicating a role for epithelial antigen processing in this phenomenon.