title: Induction of antigen-reactive and IL-2 receptor bearing cells following oral immunization in humans.
abstract: A human model of oral immunization using two forms of HI antigen preparation was studied. Oral immunization with killed HI (monobacterial) or HI in a polybacterial mix (polybacterial) induced an enhanced antigen-driven proliferative response in circulating PBL of normal subjects as well as an increase in the precursor frequency of HI antigen-specific cells using limiting dilution analysis. However, the proliferative response was better maintained at a high level in subjects after completion of immunization with the polybacterial vaccine, whereas the response was small and transient following oral immunization with the monobacterial vaccine. Clonal analysis of the proliferative response demonstrated that the precursor frequency of HI antigen-specific cells in the circulating pool was not expanded to account for the differences, despite repeated ingestion of the vaccine. An analysis of PBL following oral immunization using anti-TAC monoclonal antibody revealed an increase in the number of IL-2 receptor-bearing cells in subjects orally immunized with the polybacterial vaccine, with maximal numbers occurring at day 62 when the number of precursors fell but the proliferative response remained high. This suggests that the enhanced and sustained proliferation in bulk cultures is due in part to a contribution to the overall proliferation by in vivo polyclonally-activated IL-2 receptor positive cells which proliferate in the presence of IL-2. Taken together, the results obtained are consistent with the concept that 'restricted' cell activation may be important in the mechanism of selective protection found following oral immunization with monobacterial HI vaccine.
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000942:Antigens, Bacterial / Q000008:administration & dosage / Q000276:immunology*; D001428:Bacterial Vaccines / Q000008:administration & dosage; D006192:Haemophilus Infections / Q000517:prevention & control; D006193:Haemophilus influenzae / Q000276:immunology*; D006801:Humans; D007114:Immunization; D008213:Lymphocyte Activation; D008214:Lymphocytes / Q000276:immunology; D011971:Receptors, Immunologic / Q000096:biosynthesis*; D015375:Receptors, Interleukin-2
chemical_list: D000942:Antigens, Bacterial; D001428:Bacterial Vaccines; D011971:Receptors, Immunologic; D015375:Receptors, Interleukin-2