Endocrine Abstracts

(Aims) Regulation of humoral immunity is important to develop vaccines for infectious disease and cancer. However, human and mouse humoral immune systems contain different molecular mechanisms, and the evaluation of efficacy is difficult in the pre-clinical investigation. Humanized mice with reconstructed human immune system are useful for drug discovery of molecular-targeted drugs related to the immune system, and evaluation of antibody production by vaccines. The development of a good model for evaluating the antibody-producing ability has been awaited. However, it was difficult to develop antigen-specific IgGs in the mice, because the maintenance of fully developed T cells and B cells was not successful. We focused on the fact that the mother during pregnancy accepts the other, the foetation, while maintaining the production of specific antibodies, and attempted to produce humanized mice based on the expression of pregnancy-related protein interleukin-4 (IL-4). As we found that the mice can secrete antigen-specific antibodies, futher experiments were performed. (Materials and Methods) We immunized the 20mer HER2 peptide CH401MAP, which we developed as a breast cancer vaccine model, into NOG-hIL-4-Tg mice transplanted with healthy donor’s peripheral blood mononuclear cells (PBMCs). Then, the subsets and activation level of T cells was confirmed by flow cytometry. Glucocorticoid receptor (GR) was quantified by realtime-RT-PCR. Moreover, the antibody production performance was confirmed by ELISA/LC-MS. (Results and Discussion) As a result, in the presence of high concentration of IL-4, antigen-specific IgG antibody production was detected in the plasma of PBMC-transplanted NOG-hIL-4 mice. Because glucocorticoid suppresses not only humoral immunity but also innate and cellular immunity, we analyzed the relationship among GR expression levels, the profile of human lymphocyte subsets and the humoral immunity status of PBMC-transplanted NOG-hIL-4 mice. The results showed that NOG-hIL-4-Tg splenocytes had significantly lower human GR mRNA levels than conventional NOG splenocytes after immunization. Moreover, B-cell proportion and antigen-specific IgG concentration in plasma showed strong negative correlations with the GR mRNA level. It was considered that IL-4 decreased GR expression to increase the viability of B cells and to induce the proliferation and class switching of clones producing specific antibodies. This system may help mother’s immunity to protect their body from the infectious diseases and cancer. Moreover, it may help producing and sending pathogen-specific IgGs to their fetus.