Current models suggest that inductive immune responses to enteric Ag are initiated in Peyer's patches (PP) and mesenteric lymph nodes (MLN) followed by migration of activated, memory-like CD4+ T cells to extralymphoid sites in the intestinal lamina propria (LP). The resultant immune system contains both naive and activated T cells. To examine the differential responses of naive and memory-like T cells to oral Ag, bone marrow chimeras (BMC) were generated. Irradiated BALB/c hosts were reconstituted with a mix of DO11.10 x RAG-1-/- and BALB/c bone marrow. In unprimed DO11.10 and BMC models, LP and PP DO11.10 T cells responded to oral Ag with similar kinetics. Responses of activated, memory-like T cells to oral Ag were examined in thymectomized BMC 60 days after i.p. immunization with OVA peptide in Freund's adjuvant (OVA323-339/CFA). Results indicate that i.p. OVA323-339/CFA generated a high proportion of memory-like CD45RBlow DO11.10 T cells in peripheral lymphoid (40%) and intestinal LP (70%) tissue. Previously activated DO11.10 T cells in the LP responded to oral Ag earlier and at 50% higher levels compared with memory CD4+ T cells localized to PP tissue. These data indicate that responses to oral Ag in antigenically naive animals are initiated in PP whereas in Ag-experienced animals LP T cells respond earlier and more vigorously than cells in PP. Taken together, these data suggest that previous activation alters the hierarchy of T cell responses to oral Ag by enhancing the efficiency of LP T cell activation.
|Number of pages||6|
|Journal||Journal of Immunology|
|State||Published - Apr 15 2002|
ASJC Scopus subject areas
- Immunology and Allergy