Anti-Mouse CD4 (Clone YTS191) – Purified in vivo GOLD™ Functional Grade

In the literature, the YTS191 antibody, which targets mouse CD4, is often used alongside other antibodies to study various immune cell subsets. Some of the commonly used antibodies or proteins include:

• Anti-CD8 antibodies: These are used to study CD8+ T cells, which, like CD4+ cells, are crucial for immune responses.
• Anti-CD25 antibodies: These target the interleukin-2 receptor alpha chain, which is expressed on activated T cells and regulatory T cells.
• Anti-Gr-1 antibodies: These are used to study granulocytes, including neutrophils and monocytes.
• Anti-NK1.1 antibodies: These target natural killer (NK) cells, which are involved in innate immunity.
• Myeloid markers: These are used to identify myeloid cells, such as macrophages and dendritic cells.

In research focusing on checkpoint inhibitors or immunotherapy studies, YTS191 is often used alongside CD8-specific antibodies to deplete CD4+ T cells. Anti-CD3 antibodies are also used in some contexts to modulate T cell activity, although their applications and mechanisms differ from those of YTS191.

Key Findings from Scientific Literature on Clone YTS191

Specificity and Binding

• Clone YTS191 is a rat monoclonal antibody that specifically recognizes the mouse CD4 antigen, a 58 kDa glycoprotein expressed on thymocytes, helper T cells, regulatory T cells (Tregs), and certain subsets of natural killer T (NKT) cells, dendritic cells, and macrophages.
• YTS191 is widely used for the identification, isolation, and depletion of CD4+ T cells in immunological studies.
• Epitope Competition: YTS191 competes with clones such as GK1.5 for CD4 binding, indicating overlapping or closely adjacent epitope recognition.

Functional Applications

• Depletion in Vivo: YTS191 is effective for in vivo depletion of CD4+ T cells, as demonstrated in numerous experimental models. For example, combined use with CD8-depleting antibodies allows researchers to dissect the roles of specific T cell subsets in immune responses and disease models.
• Mechanistic Studies: YTS191 has been used to investigate the importance of CD4+ T cell help in immune responses, such as in tumor immunotherapy. Depletion of CD4+ T cells with YTS191 in mice treated with anti-PD-1+LAG-3 led to an 89% reduction in IFNγ release by tumor-infiltrating immune cells, highlighting the critical role of CD4+ T cell help in this context. Conversely, CD4+ T cell depletion in anti-PD-1+CTLA-4 treated mice increased IFNγ release, suggesting a suppressive role for Tregs in this setting.
• Transplantation Immunology: In heart transplant models, YTS191 (alongside GK1.5) was used to deplete CD4+ T cells, revealing insights into thymic reconstitution and peripheral T cell dynamics post-lymphoablation.

Interaction with Bacterial Enzymes

• Protection from Depletion: The bacterial enzyme CU43 can protect mice from YTS191-mediated CD4+ T cell depletion by cleaving Fc glycans on the antibody, thereby disabling its effector functions. This has been used as a model to study mechanisms of immune modulation and to validate the biological relevance of specific enzyme residues in vivo.
• Mechanistic Validation: Mutagenesis studies confirmed that CU43 requires both glycan and protein binding to deglycosylate IgG antibodies like YTS191 in vivo, providing a tool to dissect antibody-effector mechanisms.

Technical Notes

• Optimal Use: The optimal working dilution for YTS191 may vary by application and should be determined by the investigator; lot-specific datasheets provide detailed guidance.
• Product Forms: YTS191 is available as purified IgG, suitable for various experimental applications including flow cytometry, immunohistochemistry, and in vivo depletion.

Summary Table

Notable Citations and Contexts

• YTS191 is instrumental in defining the roles of CD4+ T cell subsets (including Tregs and helpers) in immune responses and disease models, particularly in cancer immunotherapy and transplantation.
• Its interaction with bacterial enzymes like CU43 provides a unique system to study antibody effector functions and immune modulation in vivo.
• The clone is a standard tool for CD4+ T cell depletion and is frequently cited in foundational immunology research.

These findings underscore the versatility of YTS191 as both a research tool and a means to probe complex immunological mechanisms in mice.