Optimisation of the CT h4S bioassay for detection of human interleukin-4 secreted by mononuclear cells stimulated by phytohaemaglutinin or by human leukocyte antigen mismatched mixed lymphocyte culture

n-3 Fatty Acids Modulate T-Cell Calcium Signaling in Obese Macrosomic Rats

OBJECTIVE

We investigated the effects of a diet containing EPAX-7010, rich in PUFAs such as eicosapentaenoic acid [20:5(n-3)] and docosahexaenoic acid [22:6(n-3)], i.e., a PUFA/EPAX regimen, on T-cell activation in diabetic pregnant rats and their obese pups.

RESEARCH METHODS AND PROCEDURES

Mild hyperglycemia in pregnant rats was induced by intraperitoneal injection of streptozotocin on Day 5 of gestation. T-cell blastogenesis was assayed by using (3)H-thymidine, whereas intracellular free calcium concentrations ([Ca(2+)]i) were measured by using Fura-2 in diabetic pregnant rats and their obese offspring.

RESULTS

Concavalin-A-stimulated T-cell proliferation was decreased in both pregnant diabetic rats and their obese pups as compared with control animals. Feeding the PUFA/EPAX diet restored T-cell proliferation in both groups of animals. We also employed ionomycin, which at 50 nM opens calcium channels, and thapsigargin (TG), which recruits [Ca(2+)]i from endoplasmic reticulum pool. We observed that ionomycin-induced increases in [Ca(2+)]i in T-cells of diabetic mothers and obese offspring were greater than in those of control rats. Furthermore, feeding PUFA/EPAX diet diminished significantly the ionomycin-evoked rise in [Ca(2+)]i in diabetic and obese animals. TG-induced increases in [Ca(2+)]i in T-cells of diabetic pregnant rats and their obese offspring were greater than in those of control rats. The feeding of the experimental diet significantly curtailed the TG-evoked increases in [Ca(2+)]i in both diabetic and obese rats.

DISCUSSION

Together, these observations provide evidence that T-cell activation and T-cell calcium signaling are altered during gestational diabetes and macrosomia. Hence, dietary fish oils, particularly eicosapentaenoic acid and docosahexaenoic acid, may restore these T-cell abnormalities.

Cytokine Gene Expression in Peripheral Blood Mononuclear Cells and Alloreactivity in Hematopoietic Cell Transplantation with Nonmyeloablative Conditioning

Cytokines are thought to play an important role in the pathophysiology of graft-versus-host disease (GVHD). To study the relationship between cytokines and GVHD, we obtained peripheral blood mononuclear cells (MNCs) from 21 patients with hematologic malignancies and their HLA-identical sibling donors before and sequentially after hematopoietic cell transplantation (HCT) with nonmyeloablative conditioning. The MNCs were cultured for 72 hours either alone or in mixed lymphocyte cultures with irradiated MNCs of recipient, donor, or HLA-mismatched third-party origin. The gene expression of interleukin (IL)-2, IL-4, IL-10, IL-18, tumor necrosis factor alpha, and transforming growth factor beta in each culture was then measured by real-time quantitative reverse transcriptase-polymerase chain reaction. The composition of the responder MNCs differed between patients and donors and changed after HCT, with a possible influence on the results. Early after transplantation (day +14), the IL-10 messenger RNA (mRNA) level in response to recipient or donor antigens was higher in patients who did not develop clinically significant acute GVHD when compared with the level in patients who subsequently developed acute GVHD grades II to IV (P = .005 and P = .004, respectively). The IL-10 mRNA level on day +14 was highly correlated with the pretransplantation mRNA level of the recipient MNCs but not with the level of the donor MNCs; this suggests that the IL-10 mRNA detected on day +14 originated from responder cells of recipient origin. A higher IL-10 mRNA level was found in MNCs obtained before transplantation from recipients whose disease progressed or relapsed after the transplantation when compared with the level in patients whose disease did not progress or relapse (P = .03). In conclusion, a high IL-10 gene expression in the recipient MNCs may be related to a reduced incidence of acute GVHD grades II to IV and a reduced graft-versus-tumor effect after HCT with nonmyeloablative conditioning.

Limiting Dilution Analysis of Interleukin-2 Producing Helper T-cell Frequencies as a Tool in Allogeneic Hematopoietic Cell Transplantation

BACKGROUND

A reliable in vitro test that estimates the level of ongoing alloreactivity would be valuable in allogeneic hematopoietic cell transplantation (HCT) as a help to guide clinical interventions such as donor lymphocyte infusions and changes in the immunosuppression. In the present study, the use of limiting dilution analysis of interleukin-2 (IL-2) producing helper T lymphocyte frequencies (HTL assay) as a way to quantify alloreactivity following HCT was investigated.

METHODS

Serial HTL assays were performed following allogeneic HCT with myeloablative or nonmyeloablative conditioning in 26 patients with hematologic malignancies.

RESULTS

Deviations from single-hit kinetics were frequently observed in the HTL assays and a nonlinear model was therefore used for analysis. The results of this analysis suggested the presence of an inhibitory cell population. Inhibition was observed in the majority of patients and was not restricted to a specific transplant regimen. Inhibition occurred more often with high frequencies of IL-2 producing cells, indicating a physiological role of the putative inhibitory cell population in the regulation of an immune response. Higher frequencies of IL-2 producing cells were observed in patients with acute graft-versus-host disease grades II-IV than in patients with grades 0-I (P = 0.046), indicating that the degree of ongoing alloreactivity is indeed quantified by the HTL assay.

CONCLUSIONS

We find that the HTL assay may yield interesting insight into regulation of immune responses following allogeneic HCT, but because of the complexity of the results obtained, its use as a routine procedure to guide immunosuppression cannot be recommended.