Latex Allergy FAQs
This is an attempt to give a general informative understanding to users on the issue of proteins in latex and the issues of allergies in connection with usage of gloves.
What is antigen and allergen?
Antigens are any substance that provokes an immune response when introduced into the body. It can be in the form of complex protein or carbohydrate of large molecule. This stimulates the lymphocytes to produce substances (i.e. antibodies) which would react specifically with the Antigens.
Allergens are antigens that induce allergic immune reactions typically mediated through IgE antibodies. Allergic reactions occur under conditions of prolonged exposure to a highly concentrated foreign material. Potential allergens have no effect on non-sensitised people.
What are antibodies?
Antibodies are Immunoglobulins (Ig) which are proteins produced by plasma cells and lymphocytes. There are 5 classes of antibodies, viz. IgA, IgG, IgM, IgD, IgE. IgE is concerned with allergic reactions.
How does an allergy start?
Antigens enter the body and this stimulates B and T cells, producing antibodies. The antibodies attach to mast cells which cause a gradual breakdown of the mast cells releasing histamines and other mediators. Symptoms are vessel dilation, drop in blood pressure, increased heartbeat, breathlessness, urticaria and possible unconsciousness. This is Type I reaction.There are also Type II, III and IV reactions.
What has this to do with latex gloves?
Latex has many different types of natural proteins. Some of these proteins are known to sensitise certain users. These residual proteins in gloves have been suspected of inducing Type VI reactions on sensitised users. The question of sensitisation has not been fully established but is generally agreed that high contents of residual proteins in gloves may cause sensitisation. The time for this to occur varies between individuals and also between various races but frequency or cycles of wear is the determinative factor in all cases.
What level of protein is "Safe"?
Studies conducted by the Rubber Research Institute of Malaysia show that for levels of aqueous soluble protein below 100 µg/g of glove material, 80 % of sensitised users do not show allergic responses. This study was performed on a pool of healthcare workers. Further studies are in progress on this matter.
Are proteins caused by powder on the gloves?
No, the powder on the gloves does not induce the protein reactions described above. This powder is modified corn starch which is bio-absorbable (converted to glucose when absorbed by the body), and has not been known to induce the kind of allergies usually associated with glove usage. However there is evidence that the powder may absorb protein from the host glove and therefore carry a percentage of the protein residue of the host glove.
Why then are powderfree gloves less likely to cause reactions?
The process of powder removal is an after process, meaning that the removal is carried out after the glove has been fully manufactured. This is done through a process called chlorination. While the chlorination process is principally to remove the powder, it at the same time removes a significant amount of the residual protein.
The reduction in residual protein is the reason why powderfree gloves are less likely to induce protein allergy reactions. Thus it is not the powder that is the source of protein allergy reactions.
Some process of powder removal is done by simply substituting powder with another coating agent like polyurethane or acrylic during production of the glove. While this eliminates powder from the gloves it does not remove anymore protein than a prepowdered glove. This can be misleading to end users.
What can be done to reduce Protein in Gloves?
The manufacturing process need to be extended to included the protein reduction cycle. This means that the residual proteins are reduced through intensive leaching before the gloves are coated with powder. At Adventa Health, we have managed to reduce the extractable protein level to less than 100 µg/g for prepowdered gloves as compared to a general level of 200-500µg/g in comparable products on the market.
Can using Nitrile Gloves eliminate allergy reaction?
Nitrile material does not contain proteins unlike latex. Therefore anyone who is allergic to latex proteins will not have latex protein induced allergies when using Nitrile Gloves. This is the alternative product.
However there are reported allergy reactions by users of Nitrile gloves whose allergy reactions are not due to proteins but triggered by other antigens in the synthetic material.
What are the possible tests that can determine protein levels?
There are several test methods for Protein and Allergy
1.) Modified Lowry
This is the only test recognised by the US FDA for protein determination (ASTM 5712-2000). It has a sensitivity to a minimum level of 50 µg/g, after which it is no longer indicative of the actual reading.
This is a colorimetric dye-binding assay based on differential color change in response to various concentrations of protein. It involves the extraction of residual aqueous soluble protein from NR Latex products followed by centrifugation, and Phosphotungstic acid (PTA) to remove interfering, water–soluble substances. This protein content is determined using a protein standard for quantification. Spectrophotometric measurement is made at a wavelength in the range of 600 to 750 Hz (nm).
2.) ELISA (Enzyme Linked Immunosorbent Assay)
Latex Allergy is based on human IgE reacting to certain proteins in the latex but ELISA test is based on rabbit IgE antibodies reacting with all proteins. This test is not recognised by the American Society for Testing and Materials and also not recognised by the FDA.
The test measures the antigenic protein level. One example of the available variations is the LEAP test which is an acronym for Latex ELISA for Antigenic Proteins.It uses antibodies to bind to the specific antigenic proteins (these antibodies are derived from rabbits). Antibodies bound to the proteins are then reacted with an added chemical resulting in a colour development, the intensity of which depends on the amount of antigenic protein.
3.) RAST (Radioallergosorbent Test) This is a test for measuring the allergenic protein level of gloves. The test is based on the reaction between the allergenic protein and the antibody (IgE). However, unlike LEAP, the antibody is from allergic human subjects.
The weakness of the test is that the pooled allergic patient plasma will affect the outcome and relevancy of the tests.