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 blood lymphocytes (hu-PBL-SCID mice) as an in vivo model for studying human IL-13. PBL from three donors (two allergic and one non-allergic) were prestimulated 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 physiologically active and suppressed CD14 expression, while it enhanced the expression of CD23 on human monocytes. In the in vivo experiments, SCID mice transplanted with cells from both allergic donors produced twice as high maximum levels of IgE when the cells were preincubated with IL-13 in vitro before 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. Transplanted human cells from one allergic donor examined were shown to migrate to the spleen and lungs of the recipient mice, while cells from the non-allergic donor were found only in the peritoneal cavity. Altogether, our results indicate that IL-13 enhances human IgE production in vivo and suggest that lymphocytes in allergic individuals are hyper-reactive to this cytokine. Furthermore, the allergic status of the cell donor may affect migration and engraftment of cells transplanted into SCID mice.

Human IgE production in hu-PBL-SCID mice injected with birch pollen and diesel exhaust particles.

Mice with severe combined immunodeficiency were transplanted with human peripheral blood lymphocytes (hu-PBL-SCID mice). The response to immunisation with birch pollen was used to study possible effects of diesel exhaust particles (DEP) and aluminium hydroxide (Al(OH)3) on human IgE production in this human in vivo model. The adjuvants were well tolerated, as determined by the number of human cells in the peritoneal cavity at the end of the experiments. Total and birch pollen-specific IgE was detected in 76 and 41% of the mice, respectively. In the present experiments where the mice were stimulated early with birch pollen, a doubling in percentage of hu-PBL-SCID mice with production of specific IgE was observed, as compared to later stimulation used in previous experiments. Although a tendency to higher total IgE levels was observed after treatment with DEP, no statistically significant adjuvant effect of DEP or Al(OH)3 could be demonstrated. Electron microscopy analysis after immunogold labelling showed that the major birch pollen allergen Bet v I was released from the pollen grains and adsorbed to the surface of the DEP. Early stimulation with allergen appears to be important for optimal production of specific IgE in the hu-PBL-SCID model. However, our results show that further improvements are needed in order to demonstrate the expected effects from adjuvants and environmental pollutants.

Total and birch pollen-specific human IgE in mice with severe combined immunodeficiency transplanted with human peripheral blood lymphocytes: donor dependence, seasonal variation and in vivo half-life.

BACKGROUND: There is a need for animal in vivo models in the study of human allergy. The aim of the present experiments was to study production and catabolism of human IgE in mice with severe combined immunodeficiency transplanted with human peripheral blood lymphocytes (hu-PBL-SCID mice). METHODS: Groups of SCID mice were transplanted intraperitoneally with hu-PBL from the same three donors in five experiments. Subgroups of transplanted mice were immunized with birch pollen. Production of human total and birch pollen-specific IgE in the hu-PBL-SCID mice was analyzed over a 7-week period. RESULTS: Human IgE was detected in 93% of the hu-PBL-SCID mice, and the production showed reproducible donor-dependent kinetics. Production of birch pollen-specific human IgE, however, was seen only in mice transplanted with cells from birch pollen-allergic donors. A greater proportion of the mice produced specific IgE when the experiment was started in, or some months after a birch pollen season with high pollen counts. The half-lives of passively transferred human IgE were determined to be 24.0 and 23.4 h for total and birch pollen-specific IgE, respectively. CONCLUSIONS: This study demonstrates that human IgE production in hu-PBL-SCID mice is very reproducible when the same donor is used several times. Specific IgE production in recipient mice seems to require the use of cell donors with the actual specific allergy, and is most readily obtained during or after a period of donor allergen exposure. The short half-lives found indicate that hu-PBL-SCID mice have a high ongoing production of human IgE.

Human antibody response to a pneumococcal vaccine in SCID-PBL-hu mice and simultaneously vaccinated human cell donors.

Severe combined immunodeficient (SCID) mice were transplanted intraperitoneally with human peripheral blood lymphocytes (PBL) from nine healthy human donors (SCID-PBL-hu mice). None of the donors had ever received pneumococcal vaccine. Ten days after transplantation, 62 out of 111 transplanted mice and six of the nine donors were vaccinated with a 23-valent pneumococcal polysaccharide vaccine. For each donor, human IgG was detected in 91.7-100% of the SCID-PBL-hu mice, whereas specific human IgG antipneumococcal antibodies were demonstrated in 16.7-100% of the vaccinated SCID-PBL-hu mice. Most of the mice transplanted with cells from the same donor showed similar antibody response patterns in terms of kinetics and antibody levels. A significant antibody response was only obtained in mice that received cells from donors with relatively high antipneumococcal antibody levels at the time of transplantation, or donors that showed a substantial increase in antibody levels after vaccination. The immune response in the SCID-PBL-hu mice did not always reflect the ability of the respective donor to produce antipneumococcal antibodies. The donor dependency of the antipneumococcal antibody response has great practical importance for the use of the SCID-PBL-hu model. Donors should not be chosen randomly. By selecting donors whose cells have been found to result in successful engraftment, functional SCID-PBL-hu mice can be obtained for the study of human immune responses and function in an in vivo experimental model.

Engraftment and humoral immunity in SCID and RAG-2-deficient mice transplanted with human peripheral blood lymphocytes.

SCID and RAG-2 deficient mice were transplanted intraperitoneally with human peripheral blood lymphocytes (hu-PBL-SCID and hu-PBL-RAG mice). Seven days after transplantation the mice were immunized with a pneumococcal polysaccharide vaccine. Flow cytometry analysis of cells from the peritoneal cavity and the spleen after 8-10 weeks revealed that human cells had more limited engraftment in RAG than in SCID recipient mice, and that more human cells were found in the spleen than in the peritoneal cavity. Functionality of the human cells recovered from these two locations was explored by the counting of human immunoglobulin secreting cells (hu-ISC). A total of 83% of the hu-PBL-SCID mice and 29% of the hu-PBL-RAG mice had detectable hu-ISC in the peritoneal cavity and/or the spleen. The kinetic profiles of human immunoglobulins in the mouse sera during the experiment showed donor dependency. More than 90% of the hu-PBL-SCID mice had detectable levels of human IgG, IgM and IgA, while 78% had detectable levels of IgE, whereas detectable levels of IgG, IgM, IgA and IgE were measured in 37%, 64%, 68% and 23% of the hu-PBL-RAG mice, respectively. Forty-seven per cent of immunized hu-PBL-SCID mice showed a human antipneumococcal IgG level that was significantly above the background level in non-immunized mice, while none of the hu-PBL-RAG mice produced any detectable levels of human antipneumococcal IgG. In short, human PBL showed a better engraftment and a better antibody response when transplanted into SCID mice than into RAG mice.

Specific human IgE response after immunization with birch pollen in scid mice transplanted with human peripheral blood mononuclear cells-A model for human allergy?

C.B-17 scid mice were transplanted ip with human peripheral blood mononuclear cells. Some transplanted mice were immunized ip with birch pollen. Levels of total and birch pollen-specific human IgE were measured in serum. Low levels of total human IgE were detected after 9 days. 20 days after transplantation 12 out of 12 mice transplanted with cells from a birch pollen allergic donor showed higher but variable levels of total human IgE, and a low level of birch pollen specific IgE was detected in one mouse that had not been immunized. Immunization with birch pollen did not influence the level of total human IgE. In a different experiment, mice transplanted with cells from a donor with a high level of total IgE, but without birch pollen allergy, developed high levels of total IgE 49 days after transplantation, whereas no birch pollen specific IgE was found (two immunized, two non-immunized mice). In contrast, two of four mice given cells from two donors with birch pollen allergy, but with lower levels of total IgE, produced birch pollen-specific IgE after immunization. Thus, measurable levels of total human IgE were spontaneously produced in most scid mice transplanted with human peripheral blood mononuclear cells. Detectable levels of birch pollen specific human IgE appeared to be produced in occasional non-immunized scid mice transplanted with cells from allergic donors. In mice given cells from some allergic donors, half the mice produced human birch pollen specific IgE after immunization.