Interleukin-13 and human immunoglobulin E production in severe combined immunodeficiency mice transplanted with human peripheral blood lymphocytes

As normal mice do not respond to interleukin-13 (IL-13), we have used mice with severe combined immunodeficiency transplanted with human peripheral bl ood lymphocytes (hu-PBL-SCID mice) as an in vivo model for studying human I L-13. PBL from three donors (two allergic and one non-allergic) were presti mulated with IL-13 in vitro and thereafter transplanted into SCID mice. As evidenced by flow cytometry, IL-13 in the in vitro cell cultures was physio logically active and suppressed CD14 expression, while it enhanced the expr ession of CD23 on human monocytes. In the in vivo experiments, SCID mice tr ansplanted with cells from both allergic donors produced twice as high maxi mum levels of IgE when the cells were preincubated with IL-13 in vitro befo re transplantation, as compared with mice receiving cells that had not been preincubated with IL-13. Two succeeding intraperitoneal (i.p.) injections of IL-13 resulted in a further increase of maximum IgE levels. Using cells from the non-allergic donor, no enhancing effect of IL-13 was observed. Tra nsplanted human cells from one allergic donor examined were shown to migrat e to the spleen and lungs of the recipient mice, while cells from the non-a llergic donor were found only in the peritoneal cavity. Altogether, our res ults indicate that IL-13 enhances human IgE production in vivo and suggest that lymphocytes in allergic individuals are hyper-reactive to this cytokin e. Furthermore, the allergic status of the cell donor may affect migration and engraftment of cells transplanted into SCID mice.