CD4 T-Cell Counting via Cytoplasmic Domain Binding

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Solution Overview

Problem

Current methods for detecting CD4 T-cells in whole blood samples often fail to distinguish between cell-associated and soluble forms of CD4, leading to inaccurate cell counts due to the detection of soluble CD4 lacking a cytoplasmic domain, and require complex laboratory techniques or instrumentation.

Innovation Solution

A method and kit that utilize a CD4-binding agent to bind specifically to the cytoplasmic domain of CD4, allowing for the differentiation and quantification of cell-associated CD4 T-cells by using an immunochromatographic device with a chromatographic device and antibodies or antigen-binding fragments, enabling accurate enumeration of CD4 T-cells without requiring extensive sample processing or specialized equipment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional methods detect CD4 in whole blood samples, then CD4 levels can be measured, but they cannot distinguish between cell-associated and soluble forms leading to inaccurate cell counts

Engineering Contradiction:
ImproveCD4 T-cell count accuracyVSAvoidDistinction between cell-associated and soluble CD4
Core Design Contradiction:
Measurement precisionVSLoss of information

Solution Approach 1:

The invention segments the CD4 detection process into two distinct components: a capture antibody that binds to the cytoplasmic domain of CD4 (present only on cell-associated CD4) and a detection antibody that binds to the extracellular domain. This segmentation allows the assay to specifically detect cell-associated CD4 while excluding soluble CD4, thereby resolving the information loss and improving measurement precision.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention introduces a capture antibody as an intermediary that specifically recognizes the cytoplasmic domain of CD4. This intermediary component acts as a selective gatekeeper, allowing only cell-associated CD4 to be captured and subsequently detected, while excluding soluble CD4 from the detection process. This intermediary mechanism resolves the contradiction by providing selective access to the target analyte.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If complex laboratory techniques are used to accurately count CD4 T-cells, then measurement precision improves, but device complexity and ease of operation deteriorate

Engineering Contradiction:
ImproveCD4 T-cell count accuracyVSAvoidLaboratory instrumentation requirements
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The invention employs a self-service mechanism where the capture antibody immobilized on the solid phase automatically captures cell-associated CD4 from the sample. The detection antibody then binds to the captured complex, and any unbound detection antibody is washed away. This self-contained immunocomplex formation and washing process eliminates the need for complex laboratory instrumentation, allowing the assay to be performed with simple equipment while maintaining high measurement precision.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The invention extracts the essential detection function from complex laboratory instrumentation and concentrates it into a simple immunocomplex-based assay. By taking out the core detection mechanism and implementing it through antibody-antigen interactions on a solid phase, the invention eliminates the need for flow cytometers or other complex equipment, thereby reducing device complexity while preserving measurement precision.

Inventive Principle:
Principle #2Taking out (Extraction)

3Quantity of substance

If conventional CD4 detection methods are used, then total CD4 levels can be measured, but they detect soluble CD4 lacking cytoplasmic domain leading to overestimation

Engineering Contradiction:
ImproveTotal CD4 level measurementVSAvoidCD4 T-cell count accuracy
Core Design Contradiction:
Quantity of substanceVSMeasurement precision

Solution Approach 1:

The invention applies local quality by targeting a specific region of the CD4 molecule - the cytoplasmic domain - that is exclusively present on cell-associated CD4. The capture antibody is designed to recognize this specific local region, thereby赋予ing the assay the ability to distinguish between cell-associated and soluble CD4 forms. This localized targeting approach ensures that only cell-associated CD4 is quantified, eliminating overestimation while maintaining accurate measurement of the relevant substance.

Inventive Principle:
Principle #3Local quality

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach provides rapid, accurate, and reliable measurement of CD4 T-cell numbers in whole blood samples, distinguishing between cell-associated and soluble CD4, and is suitable for point-of-care diagnostics in various environments, including resource-limited settings.

Implementation Method 1

A method and kit that utilize a CD4-binding agent to bind specifically to the cytoplasmic domain of CD4, allowing for the differentiation and quantification of cell-associated CD4 T-cells

Methodology Applied
Scientific EffectAntibody-antigen binding:

Implementation Method 2

using an immunochromatographic device with a chromatographic device and antibodies or antigen-binding fragments, enabling accurate enumeration of CD4 T-cells

Methodology Applied
Scientific EffectChromatography: Chromatography

Data Source

PatentEP2067045B1Method for determining the CD4+ t-cell count and kit therefor
Publication Date: 2020.08.05 THE MACFARLANE BURNET INST FOR MEDICAL RES & PUBLIC HEALTH LTD
  • EP2067045B1 patent drawingFigure 1A~1B
  • EP2067045B1 patent drawingFigure 2
  • EP2067045B1 patent drawingFigure 3A

AI summary

The invention provides kits and methods for detecting or monitoring the number of cells in sample. The cell comprises a cell surface associated protein (CSAP) comprising a cytoplasmic (cytosolic) and an extracellular (ecto) domain. The kit comprises: (i) a chromatographic device; and (ii) a CSAP-binding agent. The method comprises: (i) optionally contacting the sample with an agent capable of lysing or permeabilizing CSAP bearing cells; (ii) contacting the sample with a CSAP-binding agent that binds to the cytoplasmic domain of the CSAP; and (iii) directly or indirectly evaluating the level or presence of bound CSAP in the sample.