Anti-Mouse MHC Class I (H-2Kd, H-2Dd) [Clone 34-1-2S] — Purified in vivo PLATINUM™ Functional Grade

Clone 34-1-2S is most commonly used in vivo in mice to block or mask MHC class I molecules (H-2K^d and H-2D^d) on host cells, thereby interfering with CD8⁺ T cell recognition and function.

This antibody’s key in vivo applications include:

• Functional blockade/Masking of MHC Class I molecules: Administration of 34-1-2S in mice is used to mask MHC class I molecules on host cells, preventing their interaction with CD8 T cells. This is especially useful to study the roles of MHC class I in immune responses, particularly in tumor immunology and transplant rejection models.
• Depletion or modulation of CD8⁺ T cell activity: By blocking MHC class I presentation, 34-1-2S impairs CD8⁺ T cell-mediated cytotoxic responses, allowing researchers to investigate the contribution of CD8⁺ T cells to disease pathogenesis or protection in various mouse models.
• Activation of antigen-presenting cells (APCs): 34-1-2S has also been reported for in vivo activation of APCs, likely by modifying interactions between MHC class I and immune effector cells.
• Assessment of immunological pathways: Studies use 34-1-2S to clarify biological mechanisms involving MHC class I, including examining its effects in autoimmunity, viral infection, and tumor growth.

Other in vivo uses, though less common, include:

• Immunohistochemistry on tissue sections after antibody administration.
• Complement-mediated cytotoxicity in vivo, to selectively target cells expressing the relevant MHC class I molecules.

Summary table of common in vivo applications for clone 34-1-2S in mice:

In summary, clone 34-1-2S is primarily used in vivo in mice for functional blockade of MHC class I, often to study CD8⁺ T cell-dependent immune responses.

Some of the most commonly used antibodies or proteins alongside 34-1-2S (anti-mouse MHC class I H-2Kd/H-2Dd) in the literature target cell subset markers and other immune proteins involved in T cell identification, MHC complex analysis, and immunophenotyping.

Key antibodies and proteins that are regularly used in conjunction with 34-1-2S include:

• CD3: Identifies all T cells as part of the T cell receptor complex.
• CD8: Recognizes cytotoxic T cells, which specifically interact with MHC class I molecules like H-2Kd and H-2Dd.
• CD4: Marks helper T cells; often included when assessing total T cell subsets in flow cytometry panels.
• CD45: Pan-leukocyte marker, used for gating total immune populations.
• CD19/CD45R (B220): Markers for B cells; used for broader immunophenotyping of splenocytes or lymph node cells.
• MHC Class II (I-A/I-E): For distinguishing between antigen-presenting cells and T cells in multiparameter panels.
• Viability dyes or controls: Such as propidium iodide or fixable viability dyes, used in flow cytometry panels.
• Beta-2 Microglobulin: Sometimes analyzed in parallel, since it forms part of the MHC class I complex.

Additional common markers, depending on experimental goals, may include:

• NK1.1 (CD161) for natural killer cell identification.
• CD25, CD44, CD62L for delineating activation and differentiation states of T cells.
• F4/80 or CD11b/CD11c for macrophage and dendritic cell subpopulations.

These combinations are frequently used in:

• Flow cytometry panels to simultaneously identify T cell subsets, their activation status, and MHC class I expression.
• Immunohistochemistry and immunofluorescence to localize immune cells and MHC molecules within tissue.
• Functional blocking or depletion studies, where antibodies against T cell markers (like anti-CD8, anti-CD4) or MHC molecules are co-administered to dissect immune interactions in vivo or ex vivo.

In summary, 34-1-2S is nearly always used in multiparameter immunophenotyping panels, most frequently with antibodies against CD3, CD8, CD4, and other lineage and activation markers, especially in studies of T cell biology, transplantation, and tumor immunology.

The key findings from scientific citations of clone 34-1-2S concern its specificity, utility in immunological assays, and its role in antibody-mediated pathology. Clone 34-1-2S is a monoclonal antibody that specifically recognizes mouse MHC class I H-2Kd and H-2Dd alloantigens, binding a common determinant in the α3 domain of these molecules, and has applications in flow cytometry, immunohistochemistry, and in vivo experiments.

Essential details:

• Specificity: 34-1-2S targets the α3 domain of H-2Kd and H-2Dd MHC class I antigens, and cross-reacts, though more weakly, with other haplotypes such as H-2Kb, s, r, q, and p.
• Applications: Frequently cited for use in:
  • Flow cytometric analysis of mouse leukocyte populations.
  • Immunohistochemistry (for acetone-fixed frozen sections).
  • In vivo activation of antigen-presenting cells (APCs) and studies involving antigen presentation, immune cell activation, and T cell responses.
• Pathobiological studies: Recent literature has highlighted that 34-1-2S, by binding multiple MHC class I antigens (Kd, Dd, and weakly Ld), can induce acute lung injury in mouse models through complement activation, especially when antibody density is high on susceptible H-2d mice. Enhanced hexamerization of this antibody increases its pathogenic potential in vivo.

Notable biological insights:

• 34-1-2S has been instrumental in demonstrating that binding multiple MHC class I antigens simultaneously increases susceptibility to antibody-mediated injury (as demonstrated in acute lung injury models).
• It has furthered understanding of complement-dependent damage, showing that antibody hexamer formation (by mutating the Fc domain) correlates with increased tissue pathology in mice.

Technical summary:

• Clone: 34-1-2S
• Isotype: Mouse IgG2a, κ
• Applications: Flow cytometry, immunohistochemistry, in vivo studies, activation of APCs.
• Immunogen: BDF mouse spleen cells / C3HalphaBDF1 mouse splenocytes.
• Binding: Recognizes epitope in α3 domain, irrespective of β2 microglobulin presence.

Limitations and considerations:

• The antibody’s utility is primarily in mouse models, given its specificity to murine MHC class I isoforms.
• Notable pathobiological effects arise when multiple target antigens are present, relevant to studies of transfusion reactions and autoimmunity.

In summary: Clone 34-1-2S is widely cited as a tool for immunological analysis in mice, specifically targeting H-2Kd and H-2Dd MHC class I antigens. Experimental findings reveal its role in complement-mediated tissue injury when binding density and antigen multiplicity are high, making it a key reagent for both basic and translational studies of mouse immune responses and antibody-mediated pathology.

Dosing regimens for clone 34-1-2S—an anti-mouse MHC Class I monoclonal antibody—vary by the experimental context and mouse model, but published studies most commonly report intraperitoneal injections at 150 μg per mouse for in vivo blockade applications. Other applications, such as flow cytometry, use much lower amounts per assay (≤0.25 μg/test).

Key details on variation:

• In vivo blockade or depletion studies: In tumor-bearing mice, 34-1-2S is frequently administered intraperitoneally at a dose of 150 μg per mouse. This volume is typical for experiments aiming to mask MHC Class I molecules on host cells. The published study cited did not indicate strain adjustments, implying this dose serves across commonly used strains such as BALB/c and C57BL/6 unless strong strain-specific toxicity or pharmacodynamic sensitivity is observed.

• Flow cytometry and in vitro assays: For analytical experiments, dosing is much lower, e.g. ≤0.25 μg per test for splenocyte staining. Dosing is advised to be empirically optimized per cell number, typically ranging from 10^5 to 10^8 cells per test.

• Mouse strain variation: While direct evidence for dose adjustment by strain is limited, in related MHC class I antibody experiments, strains such as BALB/c and C57BL/6 are widely used without explicit dose changes. However, certain strains may require careful monitoring for immune-related adverse effects, especially if used in combination treatments (e.g., with CRP to induce TRALI models, where susceptibility can differ by strain).

• Route and frequency: The predominant route for in vivo studies is intraperitoneal injection; frequency is usually once per treatment session, but in multi-dose regimens (e.g., for depletion or immune modulation studies), doses may be repeated as dictated by experimental design.

• Disease context: In models such as immune cell depletion or transfusion-related acute lung injury (TRALI), dosing remains in the 100–200 μg/mouse range, but adjunct treatments (other antibodies, inflammatory mediators) or disease induction protocols may modulate efficacy and toxicity, potentially requiring adaptation in dose or schedule.

Summary table:

Dosing for 34-1-2S should be empirically optimized for each model, with careful monitoring for strain-specific effects and intended experimental outcome. For most published in vivo mouse studies, 150 μg per mouse i.p. is standard, with analytical assays requiring much less antibody.