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The mucosal and cellular responses of mice were studied, following mucosal-route administration of recombinant Lactococcus lactis expressing tetanus toxin fragment C (TTFC), which is a known immunogen protective against tetanus. A TTFC-specific T-cell response with a mixed profile of T-helper (Th) subset-associated cytokines was elicited in the intestine, with a Th2 bias characteristic of a mucosal response. These results correlated with the humoral response, where equivalent titers of anti-TTFC immunoglobulin G1 (IgG1) and IgG2a in serum were accompanied by an elevated IgA-specific response at more than one mucosal site. The route of vaccination had an important role in determining the immune response phenotype, as evidenced by the fact that an IgG1-biased subclass profile was obtained when lactococci were administered parenterally. Stimulation of splenic or mesenteric lymph node cells with lactococci resulted in their proliferation and the secretion of gamma interferon via antigen-specific and innate immune mechanisms. The data therefore provide further evidence of the potential of recombinant lactococcal vaccines for inducing systemic and mucosal immune responses.

Background and Objectives: Neonates are more susceptible to infections than adults, due to a less mature immune system. The objective of this study was to compare the immunophenotypes of cord blood (CB) and adult peripheral blood (APB) and to establish whether or not there are immunophenotypical differences.Methods: CB and APB were collected into CPD anticoagulant. Whole blood was stained with fluorochrome conjugated antibodies, cells were fixed, red cells were lysed, and samples were run in a FACSCanto flow cytometer.Results: Plots of SSC vs. CD45 showed two lymphocyte-like populations in CB with the same low SSC characteristics while there was only one low SSC lymphoid population in APB. The CD45 dim population included the majority of CD34 1 cells, but it also included T, B, NKT, and NK cells. The percentages of CD3 1 , CD3 1 CD4 1 , CD3 1 CD8 1 , CD19 1 , CD3 1 CD56 1 , and CD3 2 CD56 1 in the CD45 high gate of CB were similar to the percentages obtained for APB. Meanwhile, in the CD45 dim gate, the percentages were either lower (CD3 1 , CD3 1 CD4 1 , CD3 1 CD8 1 ) or higher (CD19 1 , CD3 1 CD56 1 , CD3 2 CD56 1 ) than in the CD45 high gate.Conclusions: CB presents two lymphoid populations defined by different levels of expression of the phosphatase CD45; the CD45 dim subsets likely represent cells with elevated proliferative activity possibly due to the differential expression of CD45 but still not yet immunologically mature with regard to immunophenotype and function. q

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