Frequently Asked Questions

Have a question? Consult our Frequently Asked Questions to find answers to your science and order related questions.


Are detergents used for sHLA preparations?

Soluble HLA molecules do not have a transmembrane portion. As such, no detergents are required for solubilization.

Can I freeze sHLA molecules?

We do not recommend freezing sHLA molecules as loss of activity up to 20% can occur during a freeze-thaw cycle.

Do you have sHLA-C molecules?

Pure Protein offers a selection of over 20 sHLA-C molecules for your research.

Do you have sHLA-DQ molecules?

We do offer a broad selection of DQ molecules. Please visit our product section for more information.

How do I store sHLA molecules?

Soluble HLA is preferably stored at 4˚C. We recommend to use styrofoam containers to prevent temperature fluctuations.

How many sHLA do you have?

Pure Protein is currently offering a panel of over 120 Class I proteins and over 60 Class II proteins in our catalog. Download specific HLA MAPS to find the right allele.

Is soluble HLA a liquid or a powder?

All sHLA proteins are handled in liquid form and are not available as lyophilized powder.

What buffer is used to dissolve sHLA?

All sHLA proteins are dissolved in PBS at pH 7.4 and 0.02% Sodium azide is used as a bacteriostatic preservative

What if the HLA allele I want isn’t listed as available?

Please contact [email protected] and one of our team members will be sure to get back to you with potential product alternatives.

What is the most popular Class I sHLA used?

Because of its high population occurrence, sHLA-A*02:01 is our most popular allele.

What is the most popular Class II sHLA used?

We have not noticed any preference from our customers for a specific HLA Class II allele. Proteins like DRB1*07:01, DRB1*04:01, DRB1*11:01, and DRB1*01:01 are some popular requests.

What is the shelf live of sHLA?

Our guaranteed shelf live is 1 year.

Where do I find the sequence of a specific sHLA?

All individual sequences can be extracted from the datasheet provided on the product page.


Can you test any concentration in a binding assay?

Most of our concentrations applied within our assays are standardized. We do allow customized concentrations to be applied but without guaranty of success.

Do you synthesize individual peptides?

No, we do not synthesize peptides at this time but are more than happy to get you in contact with our preferred provider.

Do you synthesize peptide libraries?

No, we do not synthesize peptide libraries at this time but obtain them from our preferred provider.

How do I start a mapping project?

If you have questions or are looking for some help in defining your project needs, reach out to our experts by visiting the Contact Us page or write us at [email protected]. One of our team members will be sure to get back to you in no time.

I am publishing a paper in which peptide binding data was used, how do I properly cite the source information?

I am publishing a paper in which and HLA assay was used, how do I properly cite the source information?
To cite the use of our assay services:
1. Please list Pure Protein, L.L.C. as the provider
2. Please list as the site the service was purchased
3. Please list the Assay purchased (peptide screening, validation, or mapping)
4. Please list the reasons the services were used
5. Please provide a PDF copy of your paper, and congratulations!

At, we encourage scientific research and are happy to review your publication at no charge. To discuss your research please email [email protected].

What are affinity categories?

In order to judge the T cell peptide epitope candidate’s immunogenic potential relative affinities of multiple peptide ligands for the same HLA receptor need to be compared. Affinity categories ranks the identified peptides into high (H), medium (M), low (L), and very low (VL) binders.

What are immunogenic hotspots?

HLA ligands are not randomly distributed along the proteins’ sequences but are located within “hotspots”, which fit proteasomal cleavage, peptide processing and HLA-binding rules. These immunological hotspots may be more stable polypeptides that better survive the highly proteolytic cytosolic environment of living cells and therefore provide focus points for T cell epitope discovery.

What are logIC₅₀’s good for?

LogIC₅₀ values measure the effectiveness of the competing test peptide so they can be prioritized into high, medium, low or very low affinity binders.

What are your acceptance (pass/fail) criteria for anIC₅₀ determination?

In order to pass an IC₅₀ determination, we require 6 points on the curve and an R2 of over 0.9.

What do I get when I order a Mapping Service?

Epitope maps for a cancer or virus-related protein will be created, showing detailed information on position of each epitope on the sequence string, their HLA-type and screening score. In addition, the map uncovers the location of immunological hotspots and cross-reactivity patterns among all HLA-molecules investigated.

What do I get when I send a peptide for validation?

High affinity binding is the critical factor controlling immunogenicity of peptides. We will determine logIC₅₀ values, provide the associated dose-response curve in graphical display and ranked your candidate into affinity categories of high, medium or low affinity.

What do I get when I send peptides for screening?

High affinity binding is the critical factor controlling immunogenicity of peptides. We will determine the screening score or approximate logIC₅₀ value of your peptide panel depending on the selected screening mode selected, and prioritize them based their rankings and their HLA-type association.

What does a FITC peptide do?

A FITC peptide acts as a tracer within the peptide binding assay against which a competitor needs to compete against so that binding strength can be determined.

What does mP mean?

The primary parameter used in FP assays is polarization [P] describing the polarization state of fluorescence with units expressed as milli P [1000 mP = P].

What does peptide validation mean?

Peptide validation services provide accurate logIC₅₀ values representative of the binding affinity of your T cell epitope peptide to confirm their immunogenic potential.


Do you have HLA Class II validation services?

We currently do not offer HLA Class II peptide binding services. However, our research department is actively persuing the development of such assays.

Do you offer discounts?

Unfortunately we do not offer discounts.

Does provide free samples?

Unfortunately, we are unable to provide free samples of our proteins.

How are HLA proteins shipped?

All HLA proteins are wrapped in an insulated pouch and shipped in styrofoam boxes containing ice packs.

How can I obtain a quote for a product order?

If you are looking to obtain a quote for a single product or multiple products, add your desired product or products to your shopping cart. When completed, proceed by clicking on the green “Checkout/Download Quote” button. You will then be directed to the Order Summary page where you will be prompted to enter your shipping information. Upon entering the relevant contact and shipping information, click the grey “Next” button at the bottom of the screen and you will be directed to the Review and Submit Order page. Here, you will be able to download your personalized quote by clicking on the “Download Quote” button at the bottom of the order summary.

How can I obtain a quote for a service order?

If you are looking to obtain a quote for a service may do so by simply selecting the service they are interested in (Peptide Epitope Validation, Peptide Epitope Screening, or T Cell Epitope Mapping), and then clicking on the green “Request A Quote” button. You will then be walked through a series of questions to help our team members formulate a custom quote based on your answers. Upon submission, HLA Protein team members will review your information and will be in touch shortly to go over your request.

How long does it take to receive a report?

Depending on the current work load and extend of the project, validation and smaller screening reports are usually available within 5-10 days after receipt of the peptide.

How long does it take to receive an order?

Pure Protein, L.L.C., routinely performs domestic shipments from Monday to Thursday for arrival the next day. For International shipments, we only ship on Mondays with an expected delivery time of 3-4 days.

I have a shipping account that I would like to use, is this possible?

Unfortunately we are unable to accommodate customer shipping accounts at this time. All customers must rely on the shipping carrier of our choice.

I ordered the wrong proteins, can I return the ones I received for different proteins?

In the event we are notified prior to product shipment, customers may be eligible for a full refund minus a 25% restocking fee. To initiate a request, please send an email including any order information to [email protected]. All refunds are at the sole discretion of Pure Protein. For orders that have already shipped, Pure Protein will work with the customer to find a solution, however refunds, exchanges, or credits are not guaranteed. In the event you are unsure of your exact needs, please contact us so that we may help you determine what products are best for your research needs.

My shipment was delayed, how do I know if the products I ordered are still good?

Soluble HLA are extremely heat stable and activity will not be affected when package content reached ambient temperatures for a view days. Immediately after arrival, put samples at 4˚C.

The ice packs in the package I received were melted, how do I know if the HLA proteins are still good?

Soluble HLA store well for days at room temperature. Because the proteins are extremely heat stable, activity will not be affected. Immediately after arrival, put samples at 4˚C.

The protein I want is not in stock, how long until it is available?

We do our best to keep all products in stock. Unfortunately, we are unable to determine when products will be available again. If you have a particular product that is not in stock please email [email protected] with the specific SKU and quantity requested.


Can sHLA molecules be used to screening for HLA specific antibodies?

Soluble HLA properly present antigenic regions and are well suited to study antibody-HLA interactions.

Do you have sHLA molecules that are loaded with a specific peptide?

We currently do not offer that product, but Pure Protein, L.L.C. routinely engages in custom research work and would welcome the opportunity to learn more about your needs. Please use the Contact Us form to submit an inquiry and we will be sure to get back to you.

I am a researcher who would like to collaborate on a project, how do I contact you regarding this opportunity?

From its beginning in 1999, Pure Protein, L.L.C., has been a collaboration focused company. We routinely work with researcher all of the world and welcome new projects. For collaboration requests and proposals please email [email protected]. We look forward to hearing from you!

I would like to use HLA proteins in a commercial service or product.

Please email [email protected] for all commercial product and service related inquiries. You may also find the information on our Commercial Use page helpful.

What are alloantibodies?

Alloantibodies are of key interest in transplantation and are directed against HLA molecules from non-self immunization events triggered by alloantigens.

What are alloantigens?

A genetically determined antigen present in some but not all individuals of a species and capable of inducing the production of an allo-antibody.

What are DSA?

Donor specific antibodies (DSA) are transplant antibodies against antigens encoded by the HLA complex that are specifically expressed by the organ donor.

What are HLA antibodies?

HLA-antibodies are antibodies against antigens encoded by the HLA complex.

What are private epitopes

Epitopes that are present only on a single HLA are called private epitopes.

What are public epitopes

Epitopes that are shared by multiple antigens are referred to as public epitopes.

What is a predictive algorithm?

Predictive analytics is the use of statistical algorithms to identify the likelihood of specific peptides to possibly bind to HLA molecules based on historical binding data.

What is a target protein?

Target proteins contain antigenic regions against which the immune system triggers an immune response against. These antigenic elements are useful markers and are potential candidates for use in vaccine development or therapeutic applications.

What is an eplet?

Eplets are clusters of polymorphic amino acids, discontinuous or linear, located on the surface of HLA molecules. Eplets have been called “functional epitopes” as they include 2 to 3 amino acids that can be recognized by HLA antibodies, among the 15 to 22 amino acids that make up an HLA epitope.

What is an HLA epitope?

An epitope, also known as antigenic determinant, is the part of an HLA that is recognized by an antibody.

Why do HLA antibodies appear?

Causes of HLA sensitization. HLA antibodies usually develop in association with exposure to non-self HLA molecules such as blood products, foreign tissue during transplantation, virus infections or during pregnancy.