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Immune Thrombocytopenia (ITP) Donor PBMCs: Anti-Platelet Autoimmunity, FcRn Biology, and Treg Research

Research Use Only (RUO). All OrganaBio disease-state donor material is intended for laboratory research, drug discovery, and non-clinical studies only. Not for therapeutic, diagnostic, or clinical manufacturing use.

Reviewed by Sarah Alter, Ph.D. — Scientific Affairs, OrganaBio. 15 years of immunology research spanning autoimmunity, cancer, and infectious disease. University of Miami Miller School of Medicine. Registered Patent Agent.

Immune thrombocytopenia (ITP) is an autoimmune bleeding disorder in which platelet destruction is driven by anti-platelet autoantibodies and, in a significant subset of patients, direct CD8+ T cell cytotoxicity against megakaryocytes. Unlike many autoimmune diseases where therapy options are limited, ITP now has an established therapeutic landscape — corticosteroids, IVIG, thrombopoietin receptor agonists (TPO-RA), rituximab, FcRn inhibitors, and BTK inhibitors — yet a substantial proportion of patients remain refractory or relapse. Understanding the cellular mechanisms that persist despite treatment, and developing the next generation of tolerance-restoring therapies, requires ITP patient peripheral blood material that captures the active autoimmune program.

The Two Mechanisms of Platelet Destruction: PBMC-Accessible Readouts

Platelet destruction in ITP operates through two mechanistically distinct pathways, both accessible through PBMC and whole blood immune profiling:

Mechanism 1 — Fc-mediated phagocytosis: Anti-platelet IgG (predominantly anti-GPIIb/IIIa, secondarily anti-GPIb/IX) opsonizes platelets, which are then cleared by FcgammaRIII (CD16)- and FcgammaRII (CD32)-expressing macrophages in the spleen and liver. In peripheral blood, this mechanism is reflected in: monocyte FcgammaRIII expression levels, anti-platelet IgG serology, B cell and plasmablast frequencies producing GPIIb/IIIa-reactive antibodies, and the opsonized platelet phagocytosis capacity of CD14+ monocytes ex vivo.

Mechanism 2 — CD8+ T cell cytotoxicity: Cytotoxic CD8+ T cells in a subset of ITP patients directly lyse megakaryocytes in the bone marrow, impairing platelet production independent of antibody-mediated clearance. This CD8+-mediated component explains why some patients fail B cell-targeting therapies and may contribute to thrombopoiesis suppression measurable as inappropriately low megakaryocyte counts despite high TPO.

B Cell and Plasmablast Compartment in ITP PBMCs

The autoantibody-producing B cell compartment in ITP peripheral blood shows several disease-specific features relevant to B cell-targeting drug development:

  • Plasmablasts: Anti-platelet-specific plasmablasts are present in ITP peripheral blood and are the proximal source of circulating anti-platelet IgG. Plasmablast frequency correlates with autoantibody titer in some cohorts and is measurable by flow cytometry (CD19+CD38hiCD27+).
  • BAFF hypersensitivity: ITP B cells show elevated BAFF-R expression and enhanced survival responses to BAFF stimulation, contributing to pathological autoantibody-producing B cell persistence. Ex vivo BAFF-stimulated B cell survival assays using ITP donor PBMCs demonstrate this BAFF hypersensitivity compared to healthy controls.
  • Memory B cell anti-platelet reactivity: Switched memory B cells in ITP peripheral blood are enriched for GPIIb/IIIa-reactive specificity. This can be measured using GPIIb/IIIa protein-coated detection reagents in B cell ELISPOT or flow-based assays from ITP PBMC preparations.

Monocyte FcgammaR Expression: The FcRn and BTK Target Platform

CD14+ monocytes are the primary FcRn-expressing peripheral blood cell type and the mechanistic target of FcRn inhibitor therapy in ITP. The three approved or late-stage FcRn inhibitors in ITP — efgartigimod, rozanolixizumab, and nipocalimab — work by competing with IgG for FcRn binding, accelerating IgG (including anti-platelet IgG) degradation.

PBMC-based pharmacodynamic assays for FcRn inhibitors in ITP include:

  • FcRn (FCGRT) mRNA and surface expression quantification on ITP monocytes versus healthy donor monocytes
  • IgG recycling assays in monocyte cultures measuring the proportion of IgG rescued from lysosomal degradation
  • Dose-response inhibition of FcRn-mediated IgG recycling by candidate FcRn blockers in ITP monocyte preparations

BTK inhibitors (rilzabrutinib, ixabtinib) reduce both autoantibody production (B cell BTK pathway) and macrophage FcgammaR-mediated platelet phagocytosis. ITP donor monocytes show elevated FcgammaRIII (CD16) expression during active disease, providing an elevated-baseline assay platform for measuring BTK inhibitor effects on Fc receptor-mediated phagocytosis.

Treg Deficiency in ITP: Quantitative and Functional Aspects

ITP is associated with both quantitative Treg reduction and functional Treg impairment — a combination that is mechanistically important for understanding the autoimmune escape that drives persistent thrombocytopenia:

FoxP3+CD25highCD4+ Treg frequency is reduced in active ITP versus healthy controls, with severity-dependent correlation — the lower the platelet count, the lower the Treg percentage in some cohorts. This deficiency is partly attributed to IL-2 deprivation: activated effector T cells in ITP consume available IL-2, starving Tregs that depend on exogenous IL-2 for proliferation and survival.

Functional implications for researchers:

  • Low-dose IL-2 therapy studies: ITP donor PBMCs provide the IL-2-deprived Treg background needed to measure Treg expansion responses to IL-2 dosing — a key pharmacodynamic readout for low-dose IL-2 clinical programs
  • Treg suppression assays: ITP patient Tregs show reduced capacity to suppress autologous effector T cell proliferation; measuring Treg restoration by experimental compounds requires the disease-state Treg baseline
  • FoxP3 stability studies: IL-6, TNF-alpha, and IL-1beta in the ITP inflammatory environment convert Tregs into pathogenic effector-like cells; studying FoxP3 stability and Treg plasticity requires ITP donor cytokine context

Th1/Th17 T Cell Profiles and CD8+ Cytotoxicity

In addition to Treg deficiency, ITP CD4+ T cells show a skew toward Th1 (IFN-gamma-producing) and Th17 (IL-17A-producing) phenotypes. This Th1/Th17 elevation contributes to both autoantibody class switching and the inflammatory microenvironment that impairs Treg function.

CD8+ T cell-mediated megakaryocyte cytotoxicity is detectable in a subset of ITP patients through: elevated CD8+CD38+ activated CD8 T cell frequencies, perforin and granzyme B expression, and in ex vivo co-culture systems using ITP patient CD8+ T cells with iPSC-derived megakaryocytes or megakaryocyte cell lines as targets.

Research Applications

  • FcRn inhibitor target engagement and pharmacodynamics: FcRn expression quantification on ITP monocytes, IgG recycling inhibition assays, total IgG reduction measurement in ITP PBMC culture systems
  • BTK inhibitor mechanism of action: B cell plasmablast generation suppression, monocyte FcgammaRIII-mediated phagocytosis inhibition using ITP-specific activated monocyte baseline
  • B cell-targeting (rituximab, anti-CD19, anti-CD38): Anti-platelet-specific B cell depletion, plasmablast suppression, memory B cell GPIIb/IIIa-reactive pool characterization
  • Treg restoration strategies: Low-dose IL-2 Treg expansion, tolerogenic DC programs, FoxP3-stabilizing compounds — measured against the ITP Treg-deficient baseline
  • Biomarker validation: Platelet count-correlated immune markers, treatment response prediction from PBMC phenotyping, relapse biomarker identification in chronic ITP
  • CD8+ cytotoxicity studies: Megakaryocyte-directed CD8 T cell assays, granzyme/perforin pathway characterization in anti-platelet CD8+ T cell populations

OrganaBio ITP Donor Collection Specifications

  • Diagnosis confirmed by hematologist; platelet count at time of collection documented
  • Disease severity classification: severe (<30,000/uL), moderate (30,000-100,000/uL) cohorts available
  • ITP phase documented: newly diagnosed (<3 months), persistent (3-12 months), chronic (>12 months)
  • Prior treatment history documented; treatment-naive cohort available
  • Anti-platelet antibody specificity (anti-GPIIb/IIIa, anti-GPIb/IX) documented where serology available
  • Same-day processing from apheresis collection; 30-minute processing standard
  • Cryopreserved lots: >80% post-thaw viability; monocyte and B cell populations preserved
  • Available as isolated PBMCs, leukopaks, or fresh whole blood

Related resources: Disease-state vs. healthy donor PBMC selection framework | Sjögren’s Syndrome Donor PBMCs: B cell hyperactivation and BAFF biology

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Andrew Larson

Managing Director, CPC Services

Andrew joins OrganaBio as a project manager with varied experience in project management, client relations, and process improvement.

Prior to OrganaBio, Andrew was a client relations manager for the cGMP nucleic acids business unit at Aldevron, coordinating and managing contracts at each stage of the contract lifecycle in support of cell and gene therapy program development. Andrew supported small- and large-scale biotechnology and pharmaceutical clients anywhere from pre-IND work through commercial supply chain establishment. Before Aldevron, Andrew was a project manager for the commercialization and business development department for Sanford Health, a worldwide hospital institution. At Sanford Health, Andrew helped manage medical device patent and prototype development efforts for employee innovations primarily in the cardiovascular, neurovascular, and software spaces. Andrew was also an engineer for Atirix Medical Systems and supported the buildout of automated analysis worksheets to streamline radiology department quality control procedures.

Andrew received his Bachelor of Science in Physics from Minnesota State University Moorhead and his Master of Science in Biomedical Engineering from the University of Minnesota. At the University of Minnesota, Andrew was part of the Center for Magnetic Resonance Research, assisting efforts to automate MRI dataset registration and workflow improvement.

Michael Dee

Associate Director, QC and Analytical Development

Michael Dee has spent the last 17 years researching the immune system. Initially studying the recombinant cytokine IL-2 and its role in T cell subset differentiation and function at the University of Miami. He also helped elucidate the lower level of TCR diversity of T regs required to prevent autoimmunity in mice. Michael also supported construction, cloning, production, purification, and testing both in vitro and in vivo a novel IL-2/IL2Rα complex currently under clinical development with BMS. Michael also was a member of the department of immunology’s program project delineating the effect of a novel Eg7GP96 heat shock protein vaccine on tumor immunity.

While at Immunity Bio (formerly Altor Biosciences), he helped to characterize over 20 novel drugs for immune modulation and treatment of cancer.  After Immunity Bio, Michael was a founding team member of HCW Biologics, where he continued his role in design and initial production and characterization of several novel biologics. He has experience with proof of principle experiments with the generation CAR-NK and CAR T cells. His research at HCW was highlighted by his discovery of a process using novel biologics to activate and expand CIML NK cells. The process and rights were sold to Wugen and is currently in Phase I clinical trials. He also is listed as an Inventor on patent number: US20210268022A1 on method of activating regulatory T cells.

Meram Alamoudi

Senior Cell Processing Specialist

Meram received her master’s degree in biomedical sciences from Barry University and bachelor’s in Biology from Palm Beach Atlantic University.

Before her position at OrganaBio, Meram conducted research at Larkin University where she worked on assessing the impact of Hurricane Maria on respiratory diseases in Puerto Rico, which provided her with insight into research investigation and analysis along with generation of grant documentation.

Valeria Beckhoff-Ferrero

Senior Bioprocess Scientist

Valeria Beckhoff Ferrero has over 8 years of experience in the fields of stem cell research and tissue engineering. Valeria received her Bachelor of Science in Biomedical Engineering, specializing in Biomaterials and Tissue Engineering, from Drexel University in Philadelphia. Valeria has expertise in problem solving and finding manufacturing solutions for isolating various types stem cells and other cell derived products from different tissues.

Before joining OrganaBio, Valeria was a lead manufacturing engineer at the Amnion Foundation. She aided in instituting a GMP infrastructure, including documentation, to manufacture clinical grade placental derived stem cells. In her role, she worked in perfecting isolation, culture, selection and cell maintenance processes for perinatal derived stem cells.

Valeria’s experience includes working as an Automation Engineer at the New York Stem Cell Foundation, where she aided in the creation and coding procedures for liquid handlers to manufacture induced pluripotent stem cells. At NYSF, Valeria researched new methods of sorting, reprogramming and differentiating iPSCs.

During her studies, Valeria worked at Thomas Jefferson University Hospital’s Radiation Oncology department, where she engineered various devices to aid in hyperthermia treatments. Additionally, Valeria co-authored multiple publications on magnetic resonance guided focused ultrasound and radiation antennas for hyperthermia treatments.

Marisa Reinoso

Director, Regional Scientific Sales

Marisa has experience leading marketing and sales life sciences programs for over a decade. Originally a lab researcher, she made the jump to marketing & sales in life sciences and never looked back.

At OrganaBio, she connects cell therapy developers on the West coast and in Asia with the healthy donor starting materials they need to develop their therapies. Prior to OrganaBio, she was the cell therapy marketing lead at Invetech, heading the launch of the company’s first cell therapy product. Marisa has led marketing programs at clinical supply companies Sherpa Clinical Packaging and PCI Pharma Services. In her spare time, Marisa enjoys traveling, eating, and pretending she’s a tennis player. She has a Bachelor of Arts in Biology from Reed College and an MBA from Portland State University.

Thelma Cela

Senior Director, Tissue Procurement

Thelma Cela is a top performing professional with over 25 years’ experience in management, leadership, business development and marketing fields with business acumen and skills in driving revenue and profit growth in multiple corporate cultures. Prior to joining OrganaBio, Thelma served as Senior Director for Health and Human Services for the Seminole Tribe of Florida. Her role had oversight for health clinics, health plan administration, the behavioral health department, and elder services. In this governmental administrative capacity, Thelma had primarily responsibility for the HHS’ divisions’ budget, capital projects, utilization management, efficiency, and efficacy.

Thelma’s prior work experiences include Vice President of Clinical Operations for OrthoNOW. In this role, she provided guidance on all clinical matters, set direction on clinical policies and procedures and monitoring healthcare policy changes. As the national Vice President of Clinical Operations, Thelma also designed, developed, and implemented guidelines and protocols and ensured compliance regarding overall patient experience.

Before joining OrthoNOW, Thelma had been recruited by Leon Medical Centers, a private healthcare company operating comprehensive medical centers to launch a new business line addressing the health and wellness of an aging population. As Director, Thelma researched, created, and launched the company’s Health Living Centers which provided first of its kind facilities in the South Florida market to offer services to the community of health aging.

Thelma has a proven track record in multiple corporate healthcare cultures having worked for Mercy Hospital where she was Senior Program Director of their Diabetes Treatment Center and Director of their Surgical Weight Loss Program. She enhanced these service lines awareness in the community, improved both lines’ clinical outcomes, and built volume growth while maintaining ongoing physician support. She served in a similar capacity for American Healthways.

Thelma earned her MBA from Miami Regional University where she graduated Cum Laude and her undergraduate degree in Psychology is from the University of Miami.

She serves on the advisory panel for Florida International University’s Women in Business Leadership Program helping future women become future business leaders through thought leadership, barrier destruction, and the power of influence.

Dominic Mancini

Vice President, Operations

Dominic Mancini brings 12 years of experience working the interfaces between Analytical Development, Process Development, Quality, and Manufacturing Science to OrganaBio. A lifelong learner, Dominic enjoys solving the many scientific and operational challenges presented in the field of cell and gene therapy.

Prior to OrganaBio, Dominic spent 8 years at Bluebird Bio as the company grew from 45 to 1200+ employees and from 1 clinical asset to a robust commercial pipeline. At Bluebird, Dominic initially supported the development and technology transfer of lentiviral vector manufacturing processes. As demand grew for lentiviral process and product characterization, Dominic led the development, qualification, transfer, and validation two commercial release methods. Dominic transitioned back to the Process Development organization to lead the vector manufacturing core team, increasing operational efficiency through a 5S implementation, process schedule intensification, and reverse technology transfer initiative. More recently, Dominic supported the build-out of bluebird’s Manufacturing Science & Technology team followed by the Data Systems & Analytics team, handling late-stage commercial asset support.

Dominic received his Bachelor of Chemical Engineering with Distinction from the University of Delaware. Dominic’s undergraduate research culminated in his thesis on heterologous expression of G-protein coupled receptors in Saccharomyces cerevisiae. After graduation, Dominic was the premier hire of the Zhou Laboratory at Brigham and Women’s hospital in Boston, MA. In three years, Dominic established an animal model of COPD and co-authored several papers with his collaborators in the Pulmonary division.

Christopher B. Goodman

Vice President, Quality & Regulatory Affairs

Christopher B. Goodman is a biopharmaceutical consultant and executive making a global impact in the cellular therapy technology arena. The scope of Christopher’s expertise encompasses Cellular Therapeutic Operations, Quality and Regulatory Affairs, Global Corporate Operations, Scientific Strategic Planning, Scientific R&D Collaborations, and Marketing & Commercialization.

Christopher recently joined OrganaBio as their Vice President of Regulatory Affairs. In this role, Christopher will be helping the company, its clients and partners navigate the complexities of the domestic and international regulatory requirements governing advanced cellular therapy products and manufacturing.

Previously, Christopher held positions with the Association for the Advancement of Blood and Biotherapies (AABB), Virgin Health Bank, Ventana Medical Systems, and Celgene.

While with AABB, he held the positions of Senior Director of New Products and Lead Quality Assessor, auditing both domestic and international organizations to known standards in an effort to promote and ensure patient quality care and manufactured product consistency and standardization within Cellular Therapy, Blood Banking, Transfusion Services, Perioperative and Donor Center industries and operations. He contributed greatly to the work of AABB’s accreditation program providing his deep breadth of knowledge and technical acumen on many committees during his tenure. His pioneering work in the realm of virtual assessments during the COVID pandemic allowed AABB to flex into the planning and execution of this novel approach to the maintenance of accreditation activities during a global travel crisis. His agile thinking and approach to planning provided as minimal disruption as possible to AABB’s customer facilities.

While working with Virgin Health Bank in the State of Qatar and the United Kingdom, Christopher advanced through a series of executive roles. He joined Virgin Health Bank as the Director of Operations, during which time he managed the successful design, and build out of a new state-of-the-art cGMP facility, the first in the Middle East. As Director and Chief Executive Officer, he directed the launch of the first Arab-centric stem cell bank, and strategically guided the organization to enhanced shareholder value and expansion across the Middle East and UK. In these roles, he also oversaw global corporate operations, research collaborations, product portfolio expansion, and regulatory framework.

Christopher managed the Detection and Chemistry Assay Development Group for Ventana Medical Systems, a global leader and innovator of tissue-based diagnostic solutions. In this role, he directed overall program goals, optimized resources, and guided technical and product direction in global regulated environments.

Prior to Ventana Medical Systems, he held the position of Director of Operations for the high-growth Cellular Therapeutics Division of Celgene. As a senior-level scientist and member of the executive team, he directed divisional operations, medical affairs and executed business and scientific strategic planning.

Danielle Smyla

Senior Director, Quality Assurance

Danielle Smyla, M.S., brings 14 years of Quality Assurance and GMP experience in the Biotechnology and Medical Device industries. Ms. Smyla is an established Quality Leader with expertise in the implementation, management and continuous improvement of Quality Management Systems for GMP operations.

Prior to joining OrganaBio, Danielle was a key member of the Quality Management team at Canon BioMedical, where she led the cross-functional development and implementation of their Quality Management System. She also managed a team of Quality Specialists and Sr. Specialists, coaching them in the implementation, management and identification of improvements to quality processes.

Ms. Smyla’s Quality-focused career is complimented by valuable hands-on experience in GMP product manufacturing, as well as R&D laboratory experimentation and formulation work in support of product development.

Danielle has earned a Master’s in Biotechnology from the Johns Hopkins University and a Bachelor of Science in Chemistry from the George Washington University.

Sarah Alter, Ph.D.

Lab Director

Sarah Alter, Ph.D., is Laboratory Director at OrganaBio, LLC, where she provides technical leadership across laboratory operations, process development, product manufacturing, and clinical sample processing services supporting cell and gene therapy developers worldwide. She brings more than 20 years of immunology and translational research experience spanning autoimmunity, oncology, and infectious disease.

Since joining OrganaBio in 2018, Dr. Alter has progressed through roles of increasing responsibility, first as Director of Immunology, leading development and manufacturing of human-derived immune cell products for immuno-oncology partners and clients; then as Senior Director of Scientific Affairs, where she served as immunology subject matter expert and shaped scientific strategy across new product launches, market analyses, and client engagements. She also served as founding Managing Director of HemaCenter, LLC, OrganaBio’s FDA-registered leukapheresis collection subsidiary, where she stood up operations, recruited the medical team, and authored governing protocols and SOPs.

Earlier in her career, Dr. Alter led preclinical R&D for IL-15–based immunotherapies at Altor BioScience (now ImmunityBio), contributing to programs that advanced into the clinic and co-authoring numerous peer-reviewed publications. She holds a Ph.D. in Immunology from the University of Miami Miller School of Medicine and an M.Sc. in Microbiology from Florida Atlantic University, and is a registered Patent Agent licensed to practice before the U.S. Patent and Trademark Office.

Carlos Carballosa, Ph.D

Vice President, Sales

Dr. Carlos Carballosa holds a doctorate in Biomedical Engineering from the University of Miami and currently leads global sales for OrganaBio as the VP of Sales. Since joining the company in 2018, Carlos has had a hand in managing all of OrganaBio’s products and services including perinatal tissue, apheresis material, and cell processing and cryopreservation support services for clinical trials.

Oscar Robles

Director, Quality Systems

Oscar Robles has over thirty years of experience in pharmaceutical and medical device industries. His main areas of expertise are in Quality Systems, Quality Assurance, Manufacturing Systems Validation, Computerized Systems Validation, implementation of GxP Computerized Systems and ERP Systems such as TrackWise, Electronic Document Management, JDEwards, SAP, and Oracle. Prior to joining OrganaBio, Oscar was a member of the Quality Management team at Apotex – Aveva Drug Delivery Systems for ten years. Oscar has earned a Master’s in Business Administration from Nova Southeastern University and a Bachelor of Science in Electrical Engineering from Florida International University.

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