What are the applications and characteristics of CD4 antibodies in immunological research?

I. What is the CD4 Molecule and Its Structure and Function?

The CD4 molecule is a single-chain glycoprotein on the cell membrane surface, belonging to the immunoglobulin superfamily. The human CD4 molecule consists of 458 amino acid residues, including a 23-amino acid signal peptide, a 374-amino acid extracellular region (with two glycosylation sites), a 21-amino acid transmembrane region, and a 40-amino acid cytoplasmic region. Its extracellular region contains four immunoglobulin variable (IgV)-like domains, enabling it to participate in specific immune recognition and signal transduction. Functionally, the CD4 molecule plays a critical role in the development, activation, and immune responses of helper T lymphocytes (Th). By interacting with major histocompatibility complex class II (MHC-II) molecules, it stabilizes the binding of the T cell receptor (TCR) to antigen peptides and participates in intracellular signal transduction, thereby regulating immune responses. The human CD4 gene is located on chromosome 2, while the mouse CD4 gene is on chromosome 6, with approximately 55% sequence homology, particularly in the highly conserved cytoplasmic region.

II. In Which Cells is the CD4 Molecule Expressed?

The expression of the CD4 molecule is cell-type-specific, primarily distributed on the surface of certain T lymphocytes and thymocytes. Additionally, under specific conditions, CD4 can also be found in some B lymphocytes, Epstein-Barr virus-transformed B cells, mononuclear phagocytes, and certain brain cells in the central nervous system. This expression pattern makes CD4 an important marker for studying immune cell differentiation and function. In experimental research, specific monoclonal antibodies (e.g., murine anti-human CD4 antibodies) are often used to detect CD4 antigen expression levels, thereby assessing the distribution and status of T cell subsets. The mouse L3T4 antigen is homologous to the human CD4 molecule, making it a common reference model in cross-species comparative studies.

III. What Are the Types and Characteristics of CD4 Antibodies?

CD4 antibodies are immunological reagents that specifically recognize and bind to the CD4 molecule. Based on their origin and structure, they can be classified into several types. Murine monoclonal antibodies are produced using hybridoma technology, offering high specificity and uniformity, making them suitable for immunoassays, flow cytometry, and immunohistochemistry. Recombinant antibodies are engineered using genetic technology, allowing for humanization or fragmentation to reduce immunogenicity and improve binding efficiency. Rabbit polyclonal antibodies, which recognize multiple epitopes, generally exhibit higher sensitivity and are suitable for detecting CD4 proteins in different conformations or modified states. These antibodies are primarily used in research for identifying, sorting, and functionally analyzing CD4+ cells, as well as constructing disease models, serving as essential tools in immunology, oncology, and infectious disease research.

IV. What Are the Applications of CD4 Antibodies in Immunological Experiments?

CD4 antibodies are widely used in in vitro immunological assays. In flow cytometry, fluorescently labeled CD4 antibodies enable quantitative analysis of the proportion and absolute count of CD4+ T cells in peripheral blood or tissue samples, which is crucial for assessing immune status (e.g., monitoring CD4+ T cells in AIDS patients). In immunohistochemistry and immunofluorescence experiments, CD4 antibodies can localize CD4 molecule expression in tissue sections, aiding research on immune cell infiltration in inflammatory or tumor microenvironments. Additionally, CD4 antibodies are used in molecular detection techniques such as Western blotting and enzyme-linked immunosorbent assays (ELISA) to analyze CD4 protein expression levels or modification states. In functional studies, CD4 antibodies can block CD4-MHC-II interactions to investigate T cell activation mechanisms or target specific cell populations via antibody-dependent cellular cytotoxicity.

V. How to Select and Research CD4 Antibody-Related Technical Strategies?

Selecting appropriate CD4 antibodies requires comprehensive consideration of experimental objectives, sample types, and detection methods. For live-cell surface labeling, low-endotoxin, high-affinity fluorescent-conjugated monoclonal antibodies should be prioritized. For fixed tissues or denatured protein analysis, antibody binding efficiency under denaturing conditions must be validated. Technically, multiple antibodies are often combined for multicolor flow cytometry to distinguish CD4+ cell subsets (e.g., regulatory T cells, Th1/Th2 cells). Additionally, CRISPR-Cas9 gene editing to construct CD4-deficient models or antibody neutralization experiments to study CD4 function are effective approaches for exploring CD4's role in immune pathways. Notably, isotype and negative controls must be included to ensure accuracy and reproducibility.

VI. What Are the Challenges and Future Directions in CD4 Antibody Research?

Although CD4 antibodies are fundamental tools in immunological research, their applications still face limitations. For instance, cross-reactivity of CD4 molecules across species may affect conclusions in comparative medical studies. Non-specific binding of antibodies may lead to false-positive results, while in vivo applications require optimization of immunogenicity and off-target effects. Future directions include developing highly specific humanized antibodies, constructing multi-epitope recognition systems to enhance sensitivity, and improving tissue penetration using nanobodies or antibody fragments. Combined with single-cell sequencing, proteomics, and other emerging technologies, CD4 antibody applications will focus more on dynamically monitoring immune microenvironments, elucidating disease mechanisms, and advancing targeted therapy development.

In summary, as essential reagents in immunological research, CD4 antibodies' molecular characteristics, expression patterns, and application technologies reflect advancements in immunoassay fields. By deeply understanding CD4 antibody selection and usage strategies, researchers can more precisely explore immune cell functions and disease mechanisms, supporting basic science and clinical translation.

VII. Which Manufacturers Provide CD4 Antibodies?

Hangzhou Start Biotech Co., Ltd. has independently developed the "CD4 Recombinant Rabbit Monoclonal Antibody (CD4 Recombinant Rabbit mAb (S-634-260))" (Catalog No.: S0B1172), a high-quality detection antibody with high specificity, high affinity, and excellent stability. This product leverages the company's advanced recombinant rabbit monoclonal antibody platform technology, enabling high-specificity recognition of CD4 molecules across multiple species, including humans, mice, and rats. It performs exceptionally well in applications such as immunohistochemistry (IHC), immunofluorescence (IF), Western blotting (WB), and flow cytometry (FACS), serving as a reliable tool for T cell subset identification, immune microenvironment analysis, and immune-related disease research.

Professional Technical Support: We provide comprehensive validation data packages for this antibody, including IHC staining patterns in various species' tissues (e.g., human tonsils, mouse spleen), flow cytometry protocols, and recommended multicolor combinations. Our technical team offers expert consultation to assist in optimizing experimental designs.

Hangzhou Start Biotech Co., Ltd. is committed to providing high-performance, highly consistent antibody tools and solutions for global immunology research, translational medicine, and in vitro diagnostics. For more details about the "CD4 Recombinant Rabbit Monoclonal Antibody" (Catalog No. S0B1172), validation data, or sample testing requests, please feel free to contact us.

Product Information