Integrated Source-to-Output Characterization of a Multicomponent Extracellular Preparation from Immunoregulatory-Conditioned Human PBMC Cultures

1. Introduction

Dendritic cells and related antigen-presenting-cell populations integrate antigenic, co-stimulatory, inhibitory, cytokine-derived, and metabolic inputs to determine whether immune encounters favor activation, restraint, or peripheral tolerance [1]. Human peripheral-blood-mononuclear-cell (PBMC)-derived culture systems have consequently become useful experimental platforms for studying how sequential environmental cues shape cellular state and extracellular output [2,3].

IL-4 and granulocyte–macrophage colony-stimulating factor (GM-CSF) are widely used to support the differentiation of monocytes into antigen-presenting cells [4]. Contemporary PBMC- and monocyte-derived culture protocols further demonstrate the utility of controlled cytokine combinations for generating experimentally defined dendritic-cell populations [5]. Subsequent IL-10 and transforming growth factor beta 1 (TGF-β1) exposure can restrain inflammatory maturation and favor regulatory-associated programs [6]. However, acquisition of a regulatory phenotype does not by itself establish stable or antigen-specific tolerogenic function, which requires dedicated phenotypic and functional validation [7]. This source-state logic provides the biological basis for testing whether sequential conditioning is preserved in the composition and future activity of the recovered extracellular output.

A second challenge is analytical: material recovered from conditioned cultures may include extracellular vesicles (EVs), non-vesicular extracellular particles, membrane-derived fragments, lipoprotein-associated structures, soluble proteins, cytokines, and other lipid–protein assemblies [8]. MISEV guidance therefore favors method-explicit, biogenesis-neutral terminology when endosomal origin and product purity have not been established [9]. Orthogonal integration is particularly important because particle size alone does not determine biogenesis, and co-isolated non-vesicular material may contribute substantially to the biological system [10].

Regulatory dendritic-cell-derived vesicles provide relevant biological precedent. Vesicular and vesicle-mimetic preparations derived from tolerogenic dendritic-cell programs have been associated with suppression of T-lymphocyte activation and other tolerance-oriented immunomodulatory effects [11]. Regulatory immune-cell-derived extracellular vesicles have subsequently been investigated across transplantation, autoimmunity, inflammation, and therapeutic immune modulation [12]. Related evidence from regulatory T-cell-derived extracellular vesicles further supports the principle that the phenotype and functional state of the source immune cell can influence the immunological properties of its extracellular output [13]. These reports establish source-state-dependent extracellular immunobiology and create a useful benchmark against which a human PBMC-derived multicomponent preparation can be positioned.

Membrane microdomains provide a complementary mechanistic framework. Lipid order, raft-associated segregation, receptor nanoclustering, and the spatial organization of signaling complexes affect antigen presentation and immune-synapse behavior [14]. In dendritic cells, the nanoscale organization of antigen-presentation machinery demonstrates that molecular positioning and membrane topology can regulate immune signaling even when the relevant molecular constituents are present [15]. More broadly, interactions between membrane topography and lateral membrane domains can influence the localization and activation of signaling proteins [16]. For a regulatory-oriented preparation, the relevant hypothesis is therefore not universal “raft repair” or activation; rather, it is the context-dependent modulation of membrane order and the relative spatial organization of activating and inhibitory interfaces.

In this study, multicomponent extracellular preparation is used as a biogenesis-neutral operational descriptor for the complete recovered output containing vesicle-associated and non-vesicular material. The descriptor identifies the analytical unit under study without collapsing it into a homogeneous extracellular-vesicle subtype. This distinction is consistent with process-defined extracellular formulations in which phospholipid-, protein-, vesicle-, and non-vesicular-associated components are preserved as an integrated analytical object rather than being designated automatically as purified exosomes [17]. Sequential IL-4/GM-CSF-supported differentiation followed by IL-10/TGF-β1 conditioning defines the source-programming axis evaluated in the retrospective archive.

The primary objective was to integrate the scientifically defensible information recoverable from a documented source-to-output archive while preserving method-specific analytical units. The analysis combines source-culture viability and cell-associated regions, an approximate particle-associated size region, reported EV-associated proteins, and a multiculture aggregate cytokine summary. A secondary objective was to translate those compositional observations into a staged membrane-microdomain and immune-function validation program. The central contribution of this study is threefold: (i) it establishes a traceable source-to-output framework for a sequentially cytokine-conditioned human PBMC-derived extracellular preparation; (ii) it prevents reduction of a heterogeneous vesicular and non-vesicular output to an unverified exosome identity; and (iii) it converts compositional observations into an explicit evidence-to-claim and prospective validation framework for tolerance-oriented biologic development. This separation between documented preparation attributes and prospective functional claims is consistent with previously proposed ex vivo traceability approaches for multicomponent phospholipoproteomic formulations [18]. The complete architecture is summarized in Figure 1.

2. Materials and Methods

2.1. Study Design and Data Provenance

This retrospective, descriptive study integrated analytical outputs from one documented human PBMC-derived source-programming workflow. Each analytical domain retained its source-specific experimental unit and was linked through a single provenance rule: only values explicitly preserved in the archive were entered into the integrated dataset [19]. No unavailable instrument-level, replicate-level, or protocol-level values were reconstructed, imputed, or inferred. This approach also preserves transparent reporting boundaries by distinguishing documented flow-cytometric events, percentages, and gated regions from raw instrument outputs that were not available for retrospective review [20]. Figure 1, Figure 2, Figure 4, and Figure 6 are conceptual or evidence-summary schematics; Figure 3 and Figure 5 visualize archived numerical summaries.

Figure 2. Stage-level source programming and analytical workflow. The biological sequence connects established human PBMC-derived cultures to differentiation support, regulatory conditioning, extracellular recovery, and multilevel analytical integration. The icons are illustrative and do not depict measured cellular morphology, absolute cell number, culture scale, or operational processing parameters.

Figure 2. Stage-level source programming and analytical workflow. The biological sequence connects established human PBMC-derived cultures to differentiation support, regulatory conditioning, extracellular recovery, and multilevel analytical integration. The icons are illustrative and do not depict measured cellular morphology, absolute cell number, culture scale, or operational processing parameters.

Figure 3. Source-culture viability and cell-associated analytical distributions visualized from archived numerical summaries. (a) Annexin V/7-AAD viability composition. (b) Parent-gate and secondary CD34/CD38-defined regions.

Figure 3. Source-culture viability and cell-associated analytical distributions visualized from archived numerical summaries. (a) Annexin V/7-AAD viability composition. (b) Parent-gate and secondary CD34/CD38-defined regions.

Figure 4. Integrated profile of the recovered extracellular preparation. Particle-associated and EV-associated protein layers converge on a biogenesis-neutral multicomponent operational identity. The particle and protein panels summarize archived qualitative records and are not raw NTA traces or uncropped immunoblot images.

Figure 4. Integrated profile of the recovered extracellular preparation. Particle-associated and EV-associated protein layers converge on a biogenesis-neutral multicomponent operational identity. The particle and protein panels summarize archived qualitative records and are not raw NTA traces or uncropped immunoblot images.

Figure 5. Archived aggregate cytokine-associated profile. (a) Reported aggregate means on a logarithmic scale. (b) Interpretation boundary integrating the documented pattern, process context, and evidence boundary.

Figure 5. Archived aggregate cytokine-associated profile. (a) Reported aggregate means on a logarithmic scale. (b) Interpretation boundary integrating the documented pattern, process context, and evidence boundary.

Figure 6. Evidence-to-claim pathway for tolerance-oriented development. Measured attributes support a multicomponent operational identity, which is linked prospectively to mechanistic and functional validation modules. The membrane and receptor representations are prospective conceptual schematics and do not constitute direct mechanistic or functional evidence.

Figure 6. Evidence-to-claim pathway for tolerance-oriented development. Measured attributes support a multicomponent operational identity, which is linked prospectively to mechanistic and functional validation modules. The membrane and receptor representations are prospective conceptual schematics and do not constitute direct mechanistic or functional evidence.

2.2. Cellular Material and Ethical Provenance

Established, de-identified, research-grade human PBMC-derived precursor cultures were maintained within the archived research program under internal study culture code FIC-BX-hPBMC-IRC-2026-01 for research use only and under controlled in vitro laboratory conditions. The cultures and associated analytical records were pre-existing and were used exclusively for retrospective analytical integration and extracellular-preparation characterization. The extracellular preparation evaluated in this study corresponds to the recovered output of the documented source-programming and extracellular-recovery workflow described below. No new human biological samples were collected for the purposes of this study, no intervention involving human participants was performed, no identifiable donor information or associated clinical data were accessed, and no novel human cell line was generated or genetically modified by the authors for the purposes of this work [21].

2.3. Sequential Cytokine Conditioning

The source cultures underwent an established sequential research procedure comprising IL-4/GM-CSF-supported differentiation, subsequent IL-10/TGF-β1 regula-tory conditioning, recovery of conditioned medium, serial clarification, and size-based extracellular-fraction recovery [22,23]. The study reports the biological sequence and pro-cessing classes required for source-to-output interpretation; implementation-specific parameters were outside the analytical scope of this retrospective integration (Table 1).

2.4. Viability and Cell-Associated Flow Cytometry

Viability was assessed with Annexin V-PE and 7-aminoactinomycin D on a FACSAria III Cell Sorter, following the standard interpretive logic of phosphatidylserine exposure and membrane permeability [24]. The represented output contained 26,071 events summarized across viable, early-apoptotic, late-apoptotic, and necrotic quadrants. Separate archived analyses reported two parent gates and corresponding CD34/CD38-defined secondary regions, retained under the neutral labels Population 1 and Population 2.

2.5. Extracellular-Fraction Recovery

Conditioned medium was recovered after the sequential source-programming stage. The archive documented serial clarification followed by a size-based extracellular-fraction recovery step [25]. The resulting complete preparation was carried forward to particle, immunoblot, and cytokine-context integration. This stage-level description defines the analytical source-to-output linkage evaluated in the present study.

2.6. Nanoparticle Tracking Analysis

Particle-associated characteristics were evaluated on a NanoSight platform [26]. The archived analytical summary described a heterogeneous signal with a predominant region at approximately 170–240 nm. This particle-associated region was integrated as a qualitative compositional layer of the recovered preparation.

2.7. Immunoblotting

The archived immunoblot summary reported evaluation and detection of CD9, CD63, CD81, and TSG101 in the recovered extracellular preparation [27]. These proteins were interpreted jointly with the particle-associated record as orthogonal evidence for an EV-associated component within the complete multicomponent output

2.8. Multiculture Cytokine Analysis

The archived analytical summary described a multiplex cytometric bead immunoassay with FCAP Array processing and labelled the cytokine output as representing ten conditioned cultures [28]. IL-10, IL-4, IL-6, TNF-α, IFN-γ, IL-2, and IL-17A were listed as assessed analytes; aggregate mean values were available for IL-10, IL-4, IL-6, and TNF-α. Because IL-10 and IL-4 were supplied during conditioning, their concentrations were interpreted as attributes of the final extracellular environment.

2.9. Statistical Analysis

The analysis reports the aggregate arithmetic means preserved in the archived cytokine summary and the directly documented event and region percentages from flow cytometry. Because the integration was descriptive and culture-level replicate values were not available across all analytical domains, no variance estimates, confidence intervals, or inferential hypothesis tests were reconstructed or performed across domains [29].

2.10. Use of Generative AI and AI-Assisted Technologies

Generative AI and AI-assisted technologies were used during manuscript preparation only to support language editing, document structuring, and the code-assisted preparation of figures explicitly identified as conceptual or evidence-summary schematics. These tools were not used to generate, modify, infer, or analyze experimental data, raw plots, replicate-level values, statistical outputs, or numerical results. Final scientific figures were reconstructed and verified using deterministic vector- and code-based workflows. All AI-assisted outputs were critically reviewed, verified, and edited by the authors, who take full responsibility for the integrity and content of the manuscript [30].

3. Results

3.1. Analytical Architecture and Experimental Units

The integrated dataset comprised source-culture, recovered-preparation, and ex-tracellular final-environment outputs. Experimental units were preserved separately for each analytical domain [31,32] (Table 2), creating a traceable bridge from source quality [33,34] to recovered-output composition [35,36].

3.2. Source-Culture Viability and Cell-Associated Analytical Regions

Among 26,071 analyzed events, 25,983 (99.66%) were viable, 86 (0.33%) were early apoptotic, no late-apoptotic events were recorded, and 2 (0.01%) were necrotic. The represented output therefore provides a high-viability source-quality anchor for the downstream extracellular observations.

Two archived cell-associated parent-gate distributions were reported as Population 1 (30.34%) and Population 2 (56.93%). Their corresponding CD34/CD38-defined secondary regions contained 98.74% and 98.63% of events, respectively. These values preserve the archived cell-associated analytical structure within the source-to-output framework.

3.3. Extracellular Particle and EV-Associated Protein Profile

The recovered extracellular preparation displayed a heterogeneous parti-cle-associated signal with a predominant archived region at approximately 170–240 nm. This observation establishes the particle-associated layer of the integrated output.

The archived immunoblot summary reported detection of CD9, CD63, CD81, and TSG101. Convergence of the particle-associated and EV-associated protein layers sup-ports a multicomponent operational identity containing a vesicle-associated compo-nent while preserving the complete recovered preparation as the analytical unit (Table 3).

3.4. Multiculture Cytokine-Associated Profile

The archived aggregate summary, labelled as representing ten conditioned cultures, reported mean cytokine-associated values of 25,320.16 pg/mL IL-10, 659.35 pg/mL IL-4, 99.61 pg/mL IL-6, and 3.01 pg/mL TNF-α. The resulting profile was strongly IL-10-dominant and adds a multiculture final-environment layer to the source-to-output framework.

IL-10 and IL-4 were inputs to the conditioning program. Their measured concentrations are therefore used as process-aware final-environment descriptors, whereas IL-6 and TNF-α are retained as aggregate extracellular signals.

Table 4. Reported aggregate cytokine-associated outputs.

Analyte	Reported mean (pg/mL)	Process context	Interpretive use
IL-10	25,320.16	Conditioning input	Final-environment descriptor
IL-4	659.35	Differentiation/conditioning input	Final-environment descriptor
IL-6	99.61	No recorded exogenous input	Aggregate extracellular signal
TNF-α	3.01	No recorded exogenous input	Aggregate extracellular signal

The archived summary designated ten conditioned cultures as the multiculture analytical unit.

Table 4. Reported aggregate cytokine-associated outputs.

Analyte	Reported mean (pg/mL)	Process context	Interpretive use
IL-10	25,320.16	Conditioning input	Final-environment descriptor
IL-4	659.35	Differentiation/conditioning input	Final-environment descriptor
IL-6	99.61	No recorded exogenous input	Aggregate extracellular signal
TNF-α	3.01	No recorded exogenous input	Aggregate extracellular signal

The archived summary designated ten conditioned cultures as the multiculture analytical unit.

3.5. Integrated Evidence Boundary and Microdomain-Oriented Framework

The convergent signature integrates sequential source programming, a high-viability represented source output, a heterogeneous particle-associated region, reported EV-associated proteins, and an IL-10-dominant multiculture final-environment summary [37,38]. This cross-domain convergence establishes a process-defined multicomponent extracellular preparation and converts its characterization into an explicit evidence-to-claim framework [39,40] (Table 5).

4. Discussion

The central contribution of this study is threefold: (i) it establishes a traceable source-to-output framework for a sequentially cytokine-conditioned human PBMC-derived extracellular preparation; (ii) it prevents reduction of a heterogeneous vesicular and non-vesicular output to an unverified exosome identity [41]; and (iii) it converts compositional observations into an explicit evidence-to-claim and prospective validation framework for tolerance-oriented biologic development [42]. This contribution is methodologically substantive because the archive spans different analytical units that are often either pooled inappropriately or reported as disconnected observations [43].

4.1. Analytical Significance of the Multicomponent Source-to-Output Framework

The represented source-culture output showed 99.66% viability, providing a source-quality anchor for the extracellular observations. The recovered preparation then displayed convergent particle- and protein-associated signals: a heterogeneous predominant region at approximately 170–240 nm and reported detection of CD9, CD63, CD81, and TSG101 [44]. Together with the aggregate extracellular cytokine profile, these findings define a coherent analytical object across source, recovery, and final-environment levels.

The multicomponent designation is scientifically useful rather than merely cautious. A preparation containing interacting vesicular, non-vesicular, protein, lipid-associated, and soluble components cannot be represented faithfully by particle size or canonical EV markers alone [45]. The biogenesis-neutral operational identity adopted here therefore preserves the complete analytical object and creates a direct route to fraction-resolved testing of complete, EV-enriched, EV-depleted, and soluble components under a common normalization scheme [46].

The IL-10-dominant aggregate final environment adds a distinct process layer. Because IL-10 and IL-4 participated in conditioning, their measured values are treated as final-environment attributes [47]. This process-aware interpretation is transferable to other conditioned secretome studies in which retained inputs, extracellular association, and source-cell output must be separated analytically [48].

4.2. Positioning Relative to Regulatory Dendritic-Cell Vesicle Studies

Regulatory dendritic-cell vesicle studies establish biological precedent for source-state-dependent extracellular immunobiology, but they examine different analytical products and validation depths. Table 6 compares the principal studies directly relevant to the present design.

The comparison identifies a complementary contribution. Earlier studies linked purified murine regulatory-DC exosomes to direct functional outcomes. The present study instead supplies the human, pre-functional analytical bridge required before a heterogeneous preparation can be assigned a reproducible identity, fractionated rationally, and advanced to functional testing. Its novelty therefore lies in the integration logic and claim architecture as well as in the specific conditioned source-to-output sequence.

4.3. Study Boundaries and Prospective Validation

The study boundaries are concentrated at the design level. The retrospective ar-chive did not contain a contemporaneous IL-4/GM-CSF-only comparator, an immuno-genic-conditioning comparator, a cell-free cytokine-processing control, a complete source-cell regulatory phenotype, auditable raw NTA and FCS exports, uncropped quantitative immunoblots, culture-level cytokine dispersion, or a responder-cell func-tional assay. Accordingly, the present evidence supports descriptive integration and an operational product identity, while conditioning causality, quantitative reproducibility, antigen specificity, membrane-microdomain remodeling, and functional tolerogenicity remain assigned to their dedicated validation modules.

The next stage follows directly from the evidence-to-claim framework. Analytical traceability should first be closed with original instrument files, quantitative im-munoblots, and fraction-level recovery records [52]. Source-cell phenotype and cell-free cy-tokine controls should then define the origin of the final-environment signature [53]. Finally, normalized comparisons of the complete preparation with EV-enriched, EV-depleted, and soluble fractions should be linked to responder proliferation, CD69/CD25 activation, Treg-associated phenotypes, cytokine shifts, antigen specificity, inflammatory rechal-lenge, membrane order, and receptor-nanoclustering endpoints [54]. This hierarchy turns the current descriptive study into an executable development program.

5. Conclusions

This study establishes a traceable source-to-output framework for a sequentially conditioned human PBMC-derived multicomponent extracellular preparation. High viability in one represented source output, a heterogeneous particle-associated region, reported EV-associated proteins, and an IL-10-dominant multiculture final-environment summary converge on a coherent, biogenesis-neutral operational identity. The integration distinguishes the complete preparation from an exosome-only product while preserving a direct route to fraction-resolved, mechanistic, and functional testing.More broadly, the paper provides a transferable methodology for characterizing multicomponent extracellular preparations without prematurely assigning exosome identity or biological function. Its evidence-to-claim structure can be applied to other conditioned secretome programs to connect source quality, compositional layers, process context, and claim-specific validation. Functional tolerogenicity, antigen specificity, and recipient-cell membrane-microdomain remodeling are therefore positioned as defined next-stage endpoints rather than diffuse interpretive caveats.