Unproven allergy tests
There are many scientifically unverified tests that claim to diagnose hidden allergies. To the lay person such techniques may appear logical but all are based on unproven scientific concepts. Unfortunately, to add to this confusion some of these techniques are promoted by medical professionals for monetary gains. The practitioners of such techniques usually cite anecdotal case reports and clinical experience as evidence. However, these experiences are not scientifically documented. Rigorous clinical studies in research establishments in different parts of the world have always shown that these tests cannot accurately identify allergy conditions. Personal discussions with Professor Dr. SGO Johansson (Head, Unit of Clinical Immunology & Allergy, Karolinska University Hospital, Sweden and former President of the World Allergy Organization and co-discoverer of the IgE molecule) show that he categorically rejects such unproven tests for diagnosis of allergy or food hypersensitivity. Scientific societies for allergy and asthma throughout the world do not support the following tests for the detection of allergy or non-allergic food hypersensitivity (also called food intolerance). Moreover, hospitals throughout the world do not use such tests for diagnosis of allergy or non-allergic hypersensitivity.

In general practitioners of unproven allergy-techniques usually claim that their tests reveal allergies or hypersensitivities that conventional allergy tests (e.g. Skin prick test or Blood allergen-specific IgE tests) do not. In fact these tests do not show anything beneficial to the patient but misguide them and delay proper treatment of their allergic condition. It is better to stay with conventional test for the detection of allergy and treatment  There are several unproven "tests" for food allergy including cytotoxic food testing, Vega testing, kinesiology, iridology, pulse testing, Alcat testing, anti-food IgG antibody testing  and Rinkel's intradermal skin testing. All these tests have little scientific basis, are unreliable and have no useful role in the assessment of allergy. Some of the more common unproven tests are listed below.

 

(1) Antigen leukocyte cellular antibody test (ALCAT). In this test, diluted blood of the patient is separately exposed to about 100 or more different extracts of foods, drugs, chemicals, pollen, mold and animal dander for several minutes. The changes in the leukocytes (white blood cells) are analyzed in a coulter-counter and then interpreted by a computer programme. Any change in the leukocyte cells, such as flattening, swelling or fragmentation in response to the allergen extract is considered evidence of allergy. The test results show no association with IgE mediated tests conducted at the same time. Moreover, repeating the test immediately with a duplicate sample of blood taken at the same time often gives different results. An extensive search of medical literature shows that there is a lack of research studies performed in established immunology laboratories to support the test as suitable to identify allergic diseases or food hypersensitivity. This test unfortunately is marketed in Malaysia for allergy diagnosis.

Another variation of this test is the Cytotoxic Testing. In this test the blood leukocytes are exposed to various allergens and the changes to the cells is analyzed under the microscope. The test is highly subjective. Anyhow there is no scientific evidence that this test provides any information on the allergy status or food hypersensitivity of the patient.

 

(2) Applied kinesiology testing. This is one of the most bizarre tests used to fool the allergy patient. The allergy suffer holds a vial containing a suspected allergen in one hand and the practitioner then bends the opposite arm to measure muscle strength. The practitioner subjectively records the decrease in strength of the arm. Any decrease in bending the arm is considered a sign of allergy. The test is still used by practitioner of alternative medicine in some parts of the world.

 

(3) Electrodermal testing. In this test the patient holds in one hand a negative electrode of wire attached to an aluminum plate. The practitioner then places vials of food extracts on the plate and then completes the circuit by probing various points on the patient’s body with a positive electrode. Fluctuations in the low-voltage electrical current supposedly indicate an allergy to a particular food. There is no scientific evidence that this test shows a response to allergy. It merely shows the electrolyte changes in the tissues probed.

 

(4) Provocation-neutralization testing. In this test, drops of suspected food allergens are placed either under the patient’s tongue (sublingual testing) or the allergens are injected subcutaneously into the skin of the upper arm. The dose of the allergen is gradually increased until one is found (the provocation dose) that makes the patient experience symptom that may be interpreted as allergic. In the skin injection test the positive response may be viewed as a wheal (raised itchy skin reaction). Then the dose is gradually decreased until one is found (the neutralization dose) that relieves the symptom. If the patient has severe allergy to a food the sublingual testing or the skin testing can trigger a life-threatening anaphylactic reaction.

In another variation of the above test called ‘Skin endpoint titration testing’ the patient receives injections under the skin of shoulder of progressively increasing doses of the allergen. The development of a wheal is considered evidence of an allergy. However, large concentration of the allergens injected under the skin can cause non-specific mast cell de-granulation resulting in a false positive reaction. Usually the positive responses in some individuals are short-lived psychological responses. Moreover, it is well known that a person may develop allergic-like symptoms after exposure to a substance without necessarily being allergic to it. The reaction occurs because of direct de-granulation of the mast cells by the allergen. Unfortunately some clinicians continue to use this test in the face of over-whelming evidence that this test is not appropriate for allergy sufferers.

 

(5) Measurement of IgG antibodies. Measurement of food specific IgG antibodies is unproven diagnostic test for allergy. IgG antibodies are part of the natural defense system of the body and develop in the blood in response to contact with foreign substances. Some private laboratories use the anti-IgG antibody test for foods or aeroallergens usually in the ELISA format to screen for 96 to 192 foods and aeroallergens. Research studies by allergy experts in various parts of the world have demonstrated that the measurement of IgG antibodies to foods as unproven for the diagnosis for food allergy or respiratory allergy through this type of testing. These tests are widely marketed as ‘non-IgE food allergy tests’ giving a false impression of the nature of test. The test does not detect non-IgE mediated allergy in general. Avoidance of unnecessary restrictive diets based on these tests may adversely affect normal growth and development of the child. The application of these tests may actually endanger some patients if applied for treatment. (see Curr Opin Allergy Clin Immunol 2005:5:261).

In general anti-food IgG antibodies are found normally in the circulating blood of normal individuals. The level of IgG antibodies tends to increase when the gut is in ‘leaky’ condition when the gastrointestinal mucosa is subjected to toxins from pathogenic bacteria in the gut. Therefore, the presence of IgG antibodies to foods consumed does not signify allergy but is part of the natural immune defense mechanism in the gastrointestinal tract. The presence of these anti-food antibodies (specifically IgG and IgA) is part of the natural defense mechanism at the gut wall to prevent foreign antigens getting into the body tissues. All normal individuals have these antibodies in the gastrointestinal tract but some individuals may have elevated levels of these antibodies in the blood circulation because of a leaky gut. Without these protective antibodies (especially IgA antibodies) there would be increased inflammation of the intestinal issue.

 

Other variations of this test include IgG4 + IgE in an ELISA format for the detection of food allergy. IgG4 antibody is protective and not allergic in is function. Moreover, this test is not sensitive because IgG4 is found in very high concentration in serum relative to IgE antibody. Hence, the serum IgG4 will interfere in the binding of the patient’s IgE antibodies to allergens on the ELISA test plate. Thus the detection of anti-IgE food allergy by this method is very insensitive. This test is most likely to detect anti-food IgG4 antibodies which have no role in the detection of allergy. Such unproven test may result in the patient being advised to avoid many types of foods which may not benefit the patient at all. Unfortunately some private laboratories in many countries including Malaysia still continue to use IgE + IgG4 test or the IgG test for allergy sufferers although there is overwhelming evidence against these tests. Distinguished allergists worldwide do not support the IgG/IgG4 tests for allergy. There are studies to show the unreliability of IgG4/IgE antibody testing for food allergy and food intolerance (Clin Exp Allergy 1998:28;1526)

 

In allergen immunotherapy the IgG and IgG4 antibody level to the vaccine allergens are raised. The IgG antibodies are protective since they block the allergens from binding to the IgE bound to mast cells. The increasing levels of IgG and IgG4 antibodies in the individual are good indicators of the success of the allergen immunotherapy. Thus, high levels of IgG antibody to the causal allergens often moderate the intensity of the allergy response in the patient. The increased levels of IgG antibodies are beneficial since they form a defense barrier against allergy. Therefore, elevated IgG and IgG4 antibodies are protective in allergy.