Comparison of the immunomodulatory effect of single MSC batches versus pooled MSC products.

Severe corticosteroid-refractory graft-versus-host-disease (GVHD) is a major non-relapse cause of mortality and morbidity after an allogeneic hematopoietic stem cell transplantation (allo-HSCT). One of the most promising treatment options is using advanced therapy medicinal products based on mesenchymal stem cells (MSCs) immunomodulation ability. The protocols of MSC application differ in many parameters including a source of MSC, a dose, a number of doses or way of preparation of the medicinal product. The process is limited by the need for laborious and expensive manufacturing processes fraught with batch-to-batch variability. In our study, we compared the immunomodulatory effects of different MSC batches versus pooled MSC, specifically the influence on lymphocyte proliferation, the metabolic activity, and the expression of activation markers on T cells. Our goal was to determine whether the effect depends on donor-to-donor heterogeneity and if pooling of MSCs could increase their immunomodulatory ability. All tested batches showed an immunomodulatory effect, with no significant differences between the groups. Our study suggests that immunosuppressive potential is comparable in single batches and pooled products, and the use of products got from individual donors is suitable to treat corticosteroid-refractory GVHD.

The Quality Control of Mesenchymal Stromal Cells by in Vitro Testing of Their Immunomodulatory Effect on Allogeneic Lymphocytes.

Mesenchymal stromal cells (MSC) represent a promising treatment of graft-versus-host disease (GVHD) in patients after allogeneic haematopoietic stem cell transplantation. We performed co-cultivation experiments with non-specifically stimulated lymphocytes to characterize the immunosuppressive activity of MSC. MSC influenced expression of some activation antigens. CD25 expression was lower with MSC and reached 55.2 % vs. 84.9 % (CD4+, P = 0.0006) and 38.8 % vs. 86.6 % (CD8+, P = 0.0003) on day +4. Conversely, CD69 antigen expression remained higher with MSC (73.3 % vs. 56.8 %, P = 0.0009; 59.5 % vs. 49.7 %, ns) and its down-regulation along with the culture time was less pronounced. MSC reduced proliferation of the stimulated lymphocytes. The cell percentages detected in daughter generations were decreased (32.82 % vs. 10.68 % in generation 4, P = 0.0004 and 29.85 % vs. 10.09 % in generation 5, P = 0.0008), resulting in a lower proliferation index with MSC (1.84 vs. 3.65, P < 0.0001). The addition of MSC affected expression of some cytokines. Production of pro-inflammatory cytokines was decreased: IL-6 (19.5 vs. 16.3 MFI; P < 0.0001 in CD3+/CD4+ and 14.5 vs. 13.2 MFI; P = 0.0128 in CD3+/CD8+), IFN-γ (13.5 vs. 12.0 MFI; P = 0.0096 in CD3+/CD4+). Expression of anti-inflammatory IL-10 was only slightly increased after the addition of MSC (ns). The analysis confirmed the immunomodulatory activity of MSC. The functional tests have proved to be an important part of the quality control of the advanced therapy cellular product intended for GVHD treatment. Future research should focus on the interaction between MSC and the patient immune environment more closely.

Histamine increases the level of IFNγ produced by HIV-1 specific CTLs and this production depends on total IgE level.

BACKGROUND: The HIV (human immunodeficiency virus) population remains a global concern whose treatment is effective, though not yet optimal. Immune based therapies have thus far been disappointing and still need to be explored further. Based on published data suggesting that the functions of cytotoxic CD8+ T lymphocytes (CTL) can be improved by histamine, we investigated the effect of histamine in vitro on HIV-1 specific CD8+ T lymphocytes in HIV+ subjects. RESULTS: 60 HIV+ subjects were included in the study. We evaluated CTL function by IFNγ (interferon gamma) production (using the enzyme-linked immunospot assay (Elispot), BD Bioscience). Changes in the production of IFNγ after incubation with histamine were compared with the levels of total IgE (immunoglobulin E, measured using a Dade Behring analyzer), because histamine is endogenously released through IgE. Activation of HIV-specific CTL by histamine occurs via H2R (histamine receptors). Thus we attempted to block this activation using cimetidine (antagonist H2R). CONCLUSIONS: We found an increase in IFNγ production after the activation of HIV-1 specific CD8+ T lymphocytes by histamine (this elevation was blocked by cimetidine), furthermore, we demonstrated a negative correlation between the production of IFNγ and levels of total IgE.