https://repository.seku.ac.ke/handle/123456789/2 2026-07-27T05:22:52Z 2026-07-27T05:22:52Z Mangare, Caroline Tischer-Zimmermann, Sabine Bonifacius, Agnes Riese, Sebastian B. Dragon, Anna C. Blasczyk, Rainer Maecker-Kolhoff, Britta Eiz-Vesper, Britta https://repository.seku.ac.ke/handle/123456789/8408 2026-07-24T08:28:49Z 2022-02-01T00:00:00Z

Variances in antiviral memory T-cell repertoire of CD45RA- and CD62L-depleted lymphocyte products reflect the need of individual T-cell selection strategies to reduce the risk of GvHD while preserving antiviral immunity in adoptive T-cell therapy Mangare, Caroline; Tischer-Zimmermann, Sabine; Bonifacius, Agnes; Riese, Sebastian B.; Dragon, Anna C.; Blasczyk, Rainer; Maecker-Kolhoff, Britta; Eiz-Vesper, Britta Introduction: Viral infections and reactivations still remain a cause of morbidity and mortality after hematopoietic stem cell transplantation due to immunodeficiency and immunosuppression. Transfer of unmanipulated donor-derived lymphocytes (DLI) represents a promising strategy for improving cellular immunity but carries the risk of graft versus host disease (GvHD). Depleting alloreactive naïve T cells (TN) from DLIs was implemented to reduce the risk of GvHD induction while preserving antiviral memory T-cell activity. Here, we compared two TN depletion strategies via CD45RA and CD62L expression and investigated the presence of antiviral memory T cells against human adenovirus (AdV) and Epstein-Barr virus (EBV) in the depleted fractions in relation to their functional and immunophenotypic characteristics. Methods: T-cell responses against ppEBV_EBNA1, ppEBV_Consensus and ppAdV_Hexon within TN-depleted (CD45RA−/CD62L−) and TN-enriched (CD45RA+/CD62L+) fractions were quantified by interferon-gamma (IFN-γ) ELISpot assay after short- and long-term in vitro stimulation. T-cell frequencies and immunophenotypic composition were assessed in all fractions by flow cytometry. Moreover, alloimmune T-cell responses were evaluated by mixed lymphocyte reaction. Results: According to differences in the phenotype composition, antigen-specific T-cell responses in CD45RA− fraction were up to 2 times higher than those in the CD62L− fraction, with the highest increase (up to 4-fold) observed after 7 days for ppEBV_EBNA1-specific T cells. The CD4+ effector memory T cells (TEM) were mainly responsible for EBV_EBNA1- and AdV_Hexon-specific T-cell responses, whereas the main functionally active T cells against ppEBV_Consensus were CD8+ central memory T cells (TCM) and TEM. Moreover, comparison of both depletion strategies indicated that alloreactivity in CD45RA− was lower than that in CD62L− fraction. Conclusion: Taken together, our results indicate that CD45RA depletion is a more suitable strategy for generating TN-depleted products consisting of memory T cells against ppEBV_EBNA1 and ppAdV_Hexon than CD62L in terms of depletion effectiveness, T-cell functionality and alloreactivity. To maximally exploit the beneficial effects mediated by antiviral memory T cells in TN-depleted products, depletion methods should be selected individually according to phenotype composition and CD4/CD8 antigen restriction. TN-depleted DLIs may improve the clinical outcome in terms of infections, GvHD, and disease relapse if selection of pathogen-specific donor T cells is not available. https://doi.org/10.1159/000516284

2022-02-01T00:00:00Z Mangare, Caroline Tischer-Zimmermann, Sabine Riese, Sebastian B. Dragon, Anna C. Prinz, Immo Blasczyk, Rainer Maecker-Kolhoff, Britta Eiz-Vesper, Britta https://repository.seku.ac.ke/handle/123456789/8407 2026-07-24T08:00:54Z 2019-03-20T00:00:00Z

Robust identification of suitable T-cell subsets for personalized CMV-specific T-cell immunotherapy using CD45RA and CD62L microbeads Mangare, Caroline; Tischer-Zimmermann, Sabine; Riese, Sebastian B.; Dragon, Anna C.; Prinz, Immo; Blasczyk, Rainer; Maecker-Kolhoff, Britta; Eiz-Vesper, Britta Viral infections and reactivations remain a serious obstacle to successful hematopoietic stem cell transplantation (HSCT). When antiviral drug treatment fails, adoptive virus-specific T-cell transfer provides an effective alternative. Assuming that naive T cells (TN) are mainly responsible for GvHD, methods were developed to generate naive T-cell-depleted products while preserving immune memory against viral infections. We compared two major strategies to deplete potentially alloreactive T cells: CD45RA and CD62L depletion and analyzed phenotype and functionality of the resulting CD45RA−/CD62L− naive T-cell-depleted as well as CD45RA+/CD62L+ naive T-cell-enriched fractions in the CMV pp65 and IE1 antigen model. CD45RA depletion resulted in loss of terminally differentiated effector memory T cells re-expressing CD45RA (TEMRA), and CD62L depletion in loss of central memory T cells (TCM). Based on these differences in target cell-dependent and target cell-independent assays, antigen-specific T-cell responses in CD62L-depleted fraction were consistently 3–5 fold higher than those in CD45RA-depleted fraction. Interestingly, we also observed high donor variability in the CD45RA-depleted fraction, resulting in a substantial loss of immune memory. Accordingly, we identified donors with expected response (DER) and unexpected response (DUR). Taken together, our results showed that a naive T-cell depletion method should be chosen individually, based on the immunophenotypic composition of the T-cell populations present. doi:10.3390/ijms20061415

2019-03-20T00:00:00Z Mangare, Caroline Mbugua, Amos Maturi, Peter Rajab, Jamila Blasczyk, Rainer Heuft, Hans-Gert https://repository.seku.ac.ke/handle/123456789/8406 2026-07-23T09:22:06Z 2015-09-25T00:00:00Z

Red cell allo- and autoimmunisation in transfused sickle cell and cancer patients in Kenyatta National Hospital, Nairobi, Kenya Mangare, Caroline; Mbugua, Amos; Maturi, Peter; Rajab, Jamila; Blasczyk, Rainer; Heuft, Hans-Gert Background: Currently, no data are available on the prevalence of red blood cell (RBC) antibody formation amongst Kenyan patients with multiple transfusion needs, such as patients with sickle cell disease (SCD) or haematological malignancies (HM) and solid (SM) malignancies. Objectives: We determined the prevalence and specificities of RBC alloantibodies and autoantibodies in two patient groups with recurrent transfusion demands at Kenyatta National Hospital, Nairobi, Kenya. Method: Between February and August 2014, 300 samples from SCD, HM and SM patients were collected and screened for alloantibodies. Samples from 51 healthy blood donors were screened for irregular antibodies and phenotyped. Results: Amongst the 228 patients with viable samples (SCD, n = 137; HM, n = 48; SM, n = 43), the median transfusion frequency was two to three events per group, 38 (16.7%) were RBC immunised and 32 (14.0%) had a positive direct antiglobulin test. We identified specific alloantibodies in six patients (2.6%). Four of these six were SCD patients (2.9%) who had specific RBC alloantibodies (anti-Cw, anti-M, anti-Cob, anti-S); amongst HM patients one had anti-K and one had anti-Lea. RBC autoantibody prevalence was 3.1% (7/228). Amongst the healthy blood donors, the Ror, ccD.ee and R2r, ccD.Ee phenotypes accounted for 82% of the Rhesus phenotypes and all were Kell negative. Conclusion: The numbers of transfusions and the rates of RBC alloantibodies are low and the most important RBC alloantibody-inducing blood group antigens are relatively homogeneously distributed in this population. A general change in the Kenyatta National Hospital pre-transfusion test regimen is thus not necessary. The current transfusion practice should be reconsidered if transfusion frequencies increase in the future. DOI: https://doi.org/10.4102/ajlm.v4i1.297

2015-09-25T00:00:00Z Ngumbi, Paul K. Mugo, Simon W. Ngaruiya, James M. https://repository.seku.ac.ke/handle/123456789/8404 2026-07-23T08:20:47Z 2018-07-01T00:00:00Z

Determination of gold nanoparticles sizes via surface plasmon resonance Ngumbi, Paul K.; Mugo, Simon W.; Ngaruiya, James M. Surface plasmon resonance technique has been highly employed in determination of the sizes of metallic nanoparticles (NPs). Generally, NP size has been viewed as a function of SPR wavelength value only, with every value of this wavelength being associated with one particular size. In this paper, gold NPs (AuNPs) prepared through the citrate reduction method with a variation in the amount of citrate used on gold (III) chloride precursor was studied. Using UV-Vis spectra analysis of the synthesized NPs in colloidal form, SPR absorption band with a wavelength ranging from 518 to 520 nm was detected. At 518 and 519 nm peaks, the recorded average NP size was 12 nm while 520 nm coincided with NPs of diameters 11 and 13 nm. This indicated that small and large AuNPs within the plasmonic size can present similar high resonance. We attribute this observation to the atomic interactions within the NPs solution hence the availability of the high density of the surface (resonance) electrons from the NPs surface atoms. DOI: 10.9790/5736-1107012529

2018-07-01T00:00:00Z