Suppression of the Immune Response by Syngeneic Splenocytes Adoptively Transferred to Sublethally Irradiated Mice

The peripheral T-cell pool consists of several, functionally distinct populations of CD8+ T cells. CD44 and CD62L are among the major surface markers that allow us to define T-cell populations. The expression of these molecules depends on the functional status of a T lymphocyte. Under lymphopenic conditions, peripheral T cells undergo homeostatic proliferation and acquire the memory-like surface phenotype CD44hiCD62Lhi. However, the data on the functional activity of these cells remains controversial. In this paper, we analyzed the effects of the adoptive transfer of syngeneic splenocytes on the recovery of CD8+ T cells in sublethally irradiated mice. Our data demonstrate that under lymphopenia, donor lymphocytes form a population of memory-like CD8+ T cells with the phenotype CD122+CD5+CD49dhiCXCR3+ that shares the phenotypic characteristics of true memory cells and suppressive CD8+ T cells. Ex vivo experiments showed that after adoptive transfer in irradiated mice, T cells lacked the functions of true effector or memory cells; the allogeneic immune response and immune response to pathogens were greatly suppressed in these mice.

Formation of a Unique Population of CD8+ T Lymphocytes after Adoptive Transfer of Syngeneic Splenocytes to Mice with Lymphopenia

Under conditions of lymphopenia, T lymphocytes proliferate and acquire a surface activation phenotype, which in many respects is similar to the phenotype of true memory T cells. We investigated the phenotypic features of the CD8+ T-cell population formed from donor lymphocytes after adoptive transfer of syngeneic splenocytes to sublethally irradiated mice. This population expresses markers CD44, CD122, CD5, CD49d and the chemokine receptor CXCR3. Thus, for the first time, the phenomenon of the formation of a population of T cells with signs of suppressive CD8+ T lymphocytes and true memory cells was demonstrated.

Features of blocking HLA-DR and HLA-G BY the human IgG fraction from the plasma of multiparous women

Aim. To obtain a purified IgG preparation from the plasma of multiparous women and to evaluate its functional activity towards HLA-DR and HLA-G molecules.Materials and Methods. IgG preparation was prepared by means of affinity chromatography using the DEAE Affi-Gel Blue system. The purity of the isolated preparation was assessed by immunoelectrophoresis. Functional activity of the IgG preparation against HLA-DR and HLA-G molecules was assessed in peripheral blood lymphocytes isolated from 14 apparently healthy men of reproductive age by flow cytometry.Results. A 30 mL IgG fraction was obtained with a protein concentration of 4.3 g/l and a residual albumin less than 0.1 g/l. The protein concentration in the obtained fraction corresponded to the lower limit of IgG concentration in human serum. Immunoelectrophoresis showed that the IgG was the only antibody fraction in the chromatographic washout. Purified IgG fraction suppressed the expression of HLA-DR and HLA-G in donor lymphocytes.Conclusion. The purified IgG fraction from multiparous women can have a significant preventive and therapeutic effect against immune disorders in the mother-embryo system and therefore might halt the development of congenital heart defects by blocking HLA-DR and HLA-G in the lymphocytes.

Targeting non-engrafting IL-2 activated intentionally mismatched donor lymphocytes with monoclonal or bispecific antibodies for treatment of otherwise incurable cancer.

e15033 Background: Cure of certain resistant cancers by donor lymphocyte infusion (DLI) following allogeneic stem cell transplantation (SCT) suggests that alloreactive lymphocytes can eliminate otherwise resistant cancer. First patient with resistant relapse following supra-lethal chemoradiotherapy treated with DLI is alive & well > 34 years; > 400 patients with hematological malignancies confirmed DLI efficacy for prevention & treatment of relapse. Using murine leukemia (BCL1) & metastatic breast cancer (4T1), IL-2 activated mismatched lymphocytes with no prior SCT eliminated otherwise lethal minimal residual disease (MRD). Using anti-EpCAM x anti-CD3 bispecific antibody (BSA) lethal melanoma was eliminated, also resulted in long-lasting immunity against lethal tumor challenge. Graft-vs-host disease (GVHD) was prevented by consistent rejection of mismatched lymphocytes. Accordingly, our goal was to develop effective immunotherapy of cancer using non-engrafting intentionally mismatched Allogeneic Targeted Activated Cancer Killer cells (ATACK) using relevant monoclonal antibodies (MoAb) or BSA. Methods: Patients with multiple myeloma & lymphoma and advanced solid tumors were treated with haploidentical or unrelated donor lymphocytes pre-activated 5 days with IL-2, following non-myeloablative conditioning with endoxan or fludarabine and IL-2 injection x5 days for in vivo lymphocyte activation. ATACK with no MoAb was investigated in 40 patients with different cancers. Safety of ATACK with MoAb was investigated in 16 patients with resistant NHL, metastatic breast, lung & colorectal cancer, using commercial MoAbs against CD20, Her-2, EGFR or VEGF, respectively, or using anti-EpCAM BSA. Results: Protocols were well-tolerated with mild transient toxicity following ATACK and BSA. No patient developed GVHD. Disease-free survival > 15 years was documented in 2/2 patient with multiple myeloma and 2/2 patients with lymphoma. Longterm progression-free survival was observed in 5/31 evaluable patients with advanced metastatic solid tumors treated with no MoAbs. Minor toxicity in targeted ATACK recipients was manageable in outpatient clinic. Conclusions: Intentionally mismatched IL-2 activated killer cells guided by MoAbs or BSA represents a promissing approach for treatment, possibly even cure, of cancer patients with MRD while avoiding GVHD.

Prophylactic donor lymphocyte infusion for relapse prevention: a meta-analysis

Objective Primary disease relapse (PDR) of malignant hematologic conditions after standard hematopoietic stem cell transplant (HSCT) is one of the most challenging diseases; therefore ongoing researches are aiming at relapse prevention and minimizing the transplant-related side effects. Prophylactic donor lymphocytes (pDLI) had been proposed as a valuable strategy for PDR prevention, but early studies had been discouraging due to the limited benefit and possible association with acute graft-versus-host disease (aGVHD). Therefore, we conducted a meta-analysis to evaluate the association between pDLI use, PDR, aGVHD and OS. Method We performed a comprehensive literature search in MEDLINE, Cochrane library and Embase database from inception to May 2019 for studies that evaluated the association between pDLI and PDR. We conducted a random effect meta-analysis of 9 studies involving a total of 748 participants (pDLI = 398, non-pDLI = 350) and reported the pooled odd ratio (OR) for association of pDLI use, PDR, aGVHD and OS. Result We found a significant decreased odd of PDR in the pDLI group (pooled OR = 0.42, 95% CI 0.30–0.58, I2 = 0%), but there was no significant increased odd of aGVHD (pooled OR of 0.98, 95% CI 0.56–1.72, I2 = 0.8%). We also found that there was an increased odd of overall survival (OS) (pooled OR 3.17, 95% CI 1.85–5.45, I2 = 50.2%). Conclusion There are significantly decreased odd of PDR and increased odd of OS in the pDLI group compared to the control group, but there is no statistically significant increased odd of aGVHD as suggested by previous studies. We concluded that pDLI is a potentially valuable method for post-transplant PDR prevention.