MHC Complexes (Major Histocompatibility Complex Proteins)

About MHC Proteins

Major Histocompatibility Complex (MHC), known as HLA in humans, is a highly polymorphic family of cell surface proteins responsible for presenting peptide antigens to T cells. MHC molecules bind intracellularly derived peptides to form peptide-MHC complexes that are displayed on the cell surface for recognition by T cell receptors (TCRs), triggering adaptive immune responses. Peptide-MHC complexes play a central role in immune surveillance and are critical targets for tumor immunotherapy.

KACTUS offers a comprehensive portfolio of high-quality recombinant MHC products including monomers, tetramers produced in either bacteria-refolded or mammalian single chain (SCT) format. We also offer custom MHC development services. Our current catalog spans a broad range of MHC alleles and clinically relevant targets such as NY-ESO-1, KRAS, and AFP, providing versatile solutions to advance drug discovery and immunotherapy development.

373 products

About MHC Proteins

Major Histocompatibility Complex (MHC), known as HLA in humans, is a highly polymorphic family of cell surface proteins responsible for presenting peptide antigens to T cells. MHC molecules bind intracellularly derived peptides to form peptide-MHC complexes that are displayed on the cell surface for recognition by T cell receptors (TCRs), triggering adaptive immune responses. Peptide-MHC complexes play a central role in immune surveillance and are critical targets for tumor immunotherapy.

KACTUS offers a comprehensive portfolio of high-quality recombinant MHC products including monomers, tetramers produced in either bacteria-refolded or mammalian single chain (SCT) format. We also offer custom MHC development services. Our current catalog spans a broad range of MHC alleles and clinically relevant targets such as NY-ESO-1, KRAS, and AFP, providing versatile solutions to advance drug discovery and immunotherapy development.

Our MHC Product Portfolio

Peptide-MHC

80+ Products

Mammalian-expressed MHC monomers & tetramers

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Peptide-ready MHC

25+ Products

Load your own peptide in-house for a custom monomer or tetramer

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Biotinylated MHC

60+ Products

Biotinylated MHC monomers or tetramers for TCR screening and more

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Fluorescent MHC

30+ Products

Identify antigen-specific T cells using FACS

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Product Features

Catalog Products

Our extensive catalog includes a wide range of MHC monomers and tetramers that are readily available to meet your research needs. Whether you are studying antigen presentation or T cell responses, our products are designed to provide reliable and consistent results.

Choice of Allele

We offer a diverse selection of alleles to ensure you can find the specific MHC molecules required for your studies. Our alleles cover various species and haplotypes, enabling precise and comprehensive immunological research.

Verified Bioactivity

Each of our MHC monomers and tetramers undergoes rigorous testing to verify bioactivity. This ensures that our products will perform as expected in your assays, providing you with confidence in your results.

Biotinylation & Fluorescent Labels

Enhance your experiments with our biotinylated and fluorescently labeled MHC monomers and tetramers. These options provide flexibility in detection methods, allowing you to choose the best approach for your flow cytometry, microscopy, or other analytical techniques.

Browse by Allele

MHC complexes play a crucial role in the immune system by presenting antigenic peptides to cytotoxic CD8+ T cells (class I) or helper CD4+ T Cells (class II).

MHC I are heterotrimers consisting of a transmembrane MHC heavy chain, a light chain known as β2-microglobulin (β2m), and an 8-10 peptide antigen. The heavy chain contains two peptide binding domains (α1 and α2), an immunoglobulin-like domain (α3), and a transmembrane region. The folding of the α1 and α2 domains forms a groove where peptide antigens bind to the MHC I complex. β2m stabilizes the peptide binding groove and MHC I presentation.

MHC II are heterodimers composed of two transmembrane proteins: an α chain and a β chain. Each chain has two extracellular domains (α1 and α2 for the α chain, and β1 and β2 for the β chain), a transmembrane segment, and a cytoplasmic tail. The α1 and β1 domains form a peptide-binding groove where peptides, typically 13-18 amino acids long, bind. This binding groove is more open-ended compared to MHC I, allowing for longer peptides.

Other Alleles

For other class I or class II alleles, or non-classical alleles, try our custom MHC services.

Custom MHC Services

Browse by Antigenic Peptide

MHC binds peptide fragments of intracellular antigens to form MHC-peptide complexes, which are transported to the cell surface and recognized by T cell receptors (TCRs) to initiate an immune response. Each nucleated cell expresses 5x10⁵ copies of each MHC I, presenting various peptides simultaneously to cytotoxic T cells. Their unique binding with TCRs is crucial for adaptive immunity and TCR-related therapies like TCR-T development. Genomic mutations in cancers produce tumor-specific peptide antigens (neoantigens), presented by MHC, which enable the immune system to target cancer cells.

GP100 Intron 4 (VYFFLPDHL)

HBV (FLLTRILTI)

HLA-E (VMAPRTLVL)

HLA-G (RIIPRHLQL)

HLA-G Free Heavy Chain

HPV16 E6 (KLPQLCTEL)

HPV16 E7 (YMLDLQPET)

KRAS G12A (VVVGAAGVGK)

KRAS G12C (VVVGACGVGK)

KRAS G12D (GADGVGKSAL)

Browse MHC Products

KRAS G12D (VVGADGVGK)

KRAS G12D (VVVGADGVGK)

KRAS G12R (VVVGARGVGK)

KRAS G12S (VVVGASGVGK)

KRAS G12V (VVGAVGVGK)

KRAS G12V (VVVGAVGVGK)

p53-R175H (HMTEVVRHC)

p53 WT (HMTEVVRRC)

PRAME (ALYVDSLFFL)

PRAME (SLLQHLIGL)

SARS-CoV-2 Epitope (NQKLIANQF)

Survivin (LMLGEFLKL)

Survivin 2B (AYACNTSTL)

WT-1 (RMFPNAPYL)

Custom Peptide

For MHCs with custom peptide sequences, submit our Custom MHC Request Form.

Alternatively, try a Peptide-Ready MHC to load your peptide in-house onto an MHC tetramer or monomer.

Custom MHC Services Peptide-ready MHC

Product Validation Data

We've demonstrated via ELISA and SPR binding assays that our MHC-peptide complexes and loaded peptide-ready MHCs have good binding affinity to TCRs. Our MHC products are well-suited for applications such as antibody binding, affinity research, TCR screening, and blocking assays.

MHC ELISA Data Biotinylated HLA-A*02:01 Monomer & SLLMWITQV

HLA-A*02:01 Tetramer & FMNKIYEI

Figure 1. Immobilized HLA-A*02:01&B2M&AFP (FMNKFIYEI) TCR at 2µg/ml (100ul/well) on the plate can bind HLA-A*02:01&B2M&AFP (FMNKFIYEI) Tetramer, His Tag with an EC50 of 26.6ng/ml determined by ELISA.

Biotinylated HLA-A*02:01 Monomer & SLLMWITQV

Figure 2. Immobilized Anti-HLA-A*02:01&B2M&NY-ESO-1 (SLLMWITQV) Antibody, hFc Tag at 1ug/ml (100ul/well) on the plate. Dose response curve for Biotinylated Human HLA-A*02:01&B2M&NY-ESO-1 (SLLMWITQV) Monomer, His Tag with the EC50 of 31.3ng/ml determined by ELISA.

HLA-G Tetramer & RIIPRHLQL

Figure 3. Human LILRB2, hFc Tag captured on CM5 Chip via Protein A can bind Human HLA-G&B2M&Peptide (RIIPRHLQL) Tetramer with an affinity constant of 4.62 nM as determined in SPR assay (Biacore T200).

HLA-A*02:01 Tetramer & YLEPGPVTA

Figure 4. In SPR analysis, the GP100 TCR & Anti-CD3 Bispecific Fusion can bind to the HLA-A*02:01&B2M&GP100 (YLEPGPVTA) complex tetramer, with an affinity constant of 0.196 nM.

HLA-A*02:01 Monomer & FMNKFIYEI

Figure 5. Human HLA-A*02:01&B2M&AFP (FMNKFIEl) Monomer, His Tag captured on CM5 Chip via Anti-His Antibody can bind HLA-A*02:01&B2M&AFP (FMNKFIYEI) TCR with an affinity constant of 0.3991 µM as determined in SPR assay (Biacore T200).

HLA-A*02:01 Tetramer & FMNKFIYEI

Figure 6. Human HLA-A*02:01&B2M&AFP (FMNKFIEl) Tetramer, His Tag captured on CM5 Chip via Anti-His Antibody can bind HLA-A*02:01&B2M&AFP (FMNKFIYEI) TCR with an affinity constant of 0.111 µM as determined in SPR assay (Biacore T200).

PE-SA Assembled Tetramer with SIINFEKL, OT1 Mouse Whole Blood

Figure 7. Flow Cytometry Analysis of OT1 Mouse Whole Blood Cells and T Cells Using PE-SA Assembled Tetramers. The right panel displays the binding of OT1 mouse T cells to the Mouse H-2K(b) & B2M & OVA (SIINFEKL) PE-SA assembled tetramer, with a significant shift in fluorescence and higher percentage of MHC PE-H positive cells (39.60% in Q5-4), compared to the left control, demonstrating effective binding and tetramer assembly.

PE-SA Assembled Tetramer with SIINFEKL, Peptide-Pulsed OT1 Mouse Spleen Blood

Figure 8. Flow Cytometry Analysis of SIINFEKL Peptide-Pulsed OT1 Mouse Spleen Cells Using PE-SA Assembled Tetramers. The right panel displays the binding of OT1 mouse spleen cells to the custom-assembled tetramer (Mouse H-2K(b) & B2M & OVA (SIINFEKL) PE-SA), with a significant shift in fluorescence and higher percentage of MHC PE-H positive cells (97.41% in Q5-4), demonstrating effective binding and tetramer assembly.