Anti-Human HLA A2,B7 (MHC Class I) - Purified in vivo PLATINUM™ Functional Grade

Clone BB7.6 is most commonly used in vivo in mice to specifically target human HLAA2 and HLAB7 molecules, particularly in models where human cells expressing these MHC class I proteins are introduced, such as xenograft and humanized mouse models.

Key in vivo applications include:

• Depletion or modulation of human HLAA2/B7expressing cells: BB7.6 can be administered to selectively deplete, block, or modulate human cells that express HLAA2 or HLAB7 in chimeric or xenograft mouse models. This is integral to studies examining immune cell dynamics, tolerance, or rejection responses when human immune cells are engrafted in immunodeficient mice.

• Tracking and identification: The antibody is used to detect the presence and distribution of human HLAA2/B7expressing cells after transplantation or adoptive transfer of human immune cells. This is often achieved in conjunction with flow cytometry or immunofluorescence to monitor engraftment efficiency and cell trafficking.

• Functional studies of antigen presentation: By binding specifically to HLAA2 and HLAB7, BB7.6 enables exploration of CD8+ T cell responses against human antigens, mechanisms of T cell activation, or rejection in context of cancer or infectious disease models using humanized mice.

• Preclinical antibody evaluation: The antibody’s low endotoxin, high purity formulation makes it suitable for functional and mechanistic studies in vivo, ensuring minimal adverse reactions in mice and reliable experimental outcomes in immune modulation experiments.

BB7.6 is not reactive to mouse MHC, so its applications are restricted to models where human HLAA2/B7 is present, and it is predominantly used for research rather than direct clinical or diagnostic procedures. Applications in mice include functional assays, cell depletion, and cell tracking via flow cytometry and related techniques.

Other antibodies and proteins frequently used with BB7.6 in the literature include:

• AntiBw4 monoclonal antibodies (mAbs) (mouse and human): These are used to distinguish Bw4 epitopes from Bw6 (targeted by BB7.6).
• Other antiBw6 mAbs (mouse and human, e.g., SFR8B6): SFR8B6 is a wellcharacterized antiBw6 antibody commonly compared or paired with BB7.6, particularly in epitope mapping and sitedirected mutagenesis studies.
• BB7.1, BB7.2, PA2.1, and MA2.1: These antiHLA monoclonal antibodies are also utilized for comparison, especially in specificity and crossreactivity studies involving various HLAB and HLAA alleles.

Additional experimental contexts may include:

• β2microglobulin (β2M): Although not an antibody, this small protein is essential for HLA class I molecule stability and often studied alongside antiHLA antibodies like BB7.6.
• Various HLA alleles or proteins: Studies involving BB7.6 frequently examine its reactivity to specific HLA class I molecules and mutants generated by sitedirected mutagenesis.

Commonly, these antibodies are applied in:

• Flow cytometry
• Epitope mapping
• Functional assays for direct HLA typing or mechanistic immunology studies.

In summary, the most referenced antibodies and proteins used with BB7.6 are antiBw4 mAbs, antiBw6 mAbs such as SFR8B6, and other HLAspecific monoclonal antibodies (BB7.1, BB7.2, PA2.1, MA2.1), frequently in combination to analyze the specificity and structural characteristics of HLA class I molecules.

Clone BB7.6 is a monoclonal antibody that has yielded important insights into HLA class I epitope recognition and immune system function through its extensive use in scientific research.

Epitope Specificity and Recognition

Clone BB7.6 recognizes the Bw6 public epitope on HLA class I molecules. More specifically, it binds to a shared epitope of the major histocompatibility complex (MHC) class I molecule human leukocyte antigen (HLA)B. This recognition is critical for understanding how antibodies distinguish between different HLA variants.

Molecular Basis of Binding

Sitedirected mutagenesis studies have revealed the precise molecular determinants of BB7.6 binding. Research demonstrated that substitution of residue 83 (G83R) abrogates binding by the BB7.6 antiBw6 monoclonal antibody, likely due to steric hindrance. This finding highlights the importance of specific amino acid residues in the 7783 region for antibody recognition. The studies indicate that even though antibodyantigen contact sites are large, a few amino acid side chains often provide most of the binding energy.

Epitope Heterogeneity

A major conclusion from research using BB7.6 is that the Bw6 epitope is heterogeneous, and antiBw6 antibodies form energetic contacts with particular amino acids in the 7783 region. This heterogeneity means that Bw6 epitopes are best regarded as families of related structures rather than a single uniform target.

Functional Context

The antibody recognizes epitopes on HLAB molecules, which are type I transmembrane glycoproteins that form part of the MHC class I complex. These molecules play a critical role in the adaptive immune response by presenting endogenous antigens to cytotoxic CD8 T cells. Understanding how BB7.6 recognizes these molecules helps elucidate the broader mechanisms of immune recognition and HLAmediated immune responses.

There is insufficient published data directly detailing how the dosing regimens of clone BB7.6 (an antiHLAA2 antibody) vary across different mouse models. Most available information related to BB7.6 focuses on its specificity, applications in flow cytometry, and use in identifying or depleting human HLAA2 or A2/B7expressing cells in mice engrafted with human tissues or cells.

Essential context and supporting details:

• No standardized or widely reported dosing regimens for clone BB7.6 in murine models are found in the published literature or antibody supplier technical documentation.
• When used in vivo, dosing regimens for mouse monoclonal antibodies against human proteins often vary depending on:
  • The application (e.g., cell depletion, blocking, detection)
  • The level and location of antigen expression
  • The immunogenicity or pharmacokinetics of the antibody in the particular mouse strain/model used.
• For comparable mouse antihuman antibodies (e.g., immune cell depleters such as GK1.5, 2.43, or RB68C5), commonly reported dosing ranges are 100–300 μg per mouse, typically administered intraperitoneally two to three times per week, though this varies by target and experimental objective.

Additional relevant information:

• BB7.6 is most frequently used as a detection antibody for flow cytometry or immunohistochemistry, not as an in vivo depleting or blocking antibody.
• For in vivo applications (e.g., in humanized or xenograft models), pilot experiments with titration are usually necessary to determine optimal dosing, given potential differences in antibody clearance, target engagement, and mouse immune response.
• When highly specific information on clone BB7.6 is unavailable, researchers may extrapolate starting doses from protocols employing structurally or functionally similar antibodies, then adjust based on pilot pharmacokinetic or pharmacodynamic findings.

In summary, there are no standardized or published clone BB7.6 dosing regimens across mouse models. Empirical titration based on the scientific objective, similar antibody precedents, and mouse model specifics remains the recommended approach.