Reviewing the association between aluminum adjuvants in the vaccines and autism spectrum disorder.

The manuscript reviews the association between aluminum adjuvants (AlAd) in vaccines and autism spectrum disorder (ASD). Aluminum (Al) is neurotoxic. Infants who have received AlAd in vaccines show a higher rate of ASD. The behavior of mice changes with Al injection. Patients suffering from ASD have higher concentrations of Al in their brains. Thus, AlAd is an etiologic factor in ASD. Immune efficacy led to the use of the AlAd in vaccines; however, the safety of those who are vaccinated with such vaccines has not been considered. The mechanisms of action of AlAd and the pharmacodynamics of injected AlAd used in vaccines are not well-characterized. The association between aluminum adjuvants in the vaccines and autism spectrum disorder is suggested by multiple lines of evidence.

Simultaneous testing of immunological sensitization to multiple antigens in sarcoidosis reveals an association with inorganic antigens specifically related to a fibrotic phenotype.

Organic and inorganic antigens were studied simultaneously in the same cohort of sarcoidosis patients to investigate whether correlations between clinical characteristics and immunological sensitization could reveal new phenotypes. Sensitization to antigens of mycobacteria, Propionibacterium acnes catalase and vimentin was investigated in 201 sarcoidosis and 51 obstructive sleep apnoea patients, serving as control group. Sensitization to aluminium, beryllium, silica and zirconium was also studied in 105 of the sarcoidosis patients and in 24 of the controls. A significantly higher percentage of sarcoidosis patients (27·6%) than controls (4·2%) had an immunological response to metals or silica (P = 0·014). A higher percentage of these sarcoidosis patients showed fibrosis on chest X-ray 5 years after the diagnosis (69·2 versus 30·3%, P = 0·016). No significant differences in mycobacterial or vimentin enzyme-linked immunospot (ELISPOT) assay results were observed between sarcoidosis and control patients. A significantly lower percentage of sarcoidosis patients (3·5%) than control patients (15·7%) had a positive ELISPOT for P. acnes catalase (P = 0·003). However, sarcoidosis patients sensitized to P. acnes catalase were more likely to have skin involvement, while sarcoidosis patients sensitized to mycobacterial antigens were more likely to have cardiac involvement. Our study suggests a more prominent role for inorganic triggers in sarcoidosis pathogenesis than previously thought. Immunological sensitization to inorganic antigens was associated with development of fibrotic sarcoidosis. No association was found between sensitization to bacterial antigens or vimentin and sarcoidosis in Dutch patients. However, our data suggest that trigger-related phenotypes can exist in the heterogeneous population of sarcoidosis patients.

Treating ischemia via recruitment of antigen-specific T cells.

Ischemic diseases are a leading cause of mortality and can result in autoamputation of lower limbs. We explored the hypothesis that implantation of an antigen-releasing scaffold, in animals previously vaccinated with the same antigen, can concentrate TH2 T cells and enhance vascularization of ischemic tissue. This approach may be clinically relevant, as all persons receiving childhood vaccines recommended by the Centers for Disease Control and Prevention have vaccines that contain aluminum, a TH2 adjuvant. To test the hypothesis, mice with hindlimb ischemia, previously vaccinated with ovalbumin (OVA) and aluminum, received OVA-releasing scaffolds. Vaccinated mice receiving OVA-releasing scaffolds locally concentrated antigen-specific TH2 T cells in the surrounding ischemic tissue. This resulted in local angiogenesis, increased perfusion in ischemic limbs, and reduced necrosis and enhanced regenerating myofibers in the muscle. These findings support the premise that antigen depots may provide a treatment for ischemic diseases in patients previously vaccinated with aluminum-containing adjuvants.

Ag85b/ESAT6-CFP10 adjuvanted with aluminum/poly-IC effectively protects guinea pigs from latent mycobacterium tuberculosis infection.

The high global burden of tuberculosis (TB) underscores the urgent need for an effective TB vaccine since the only licensed Bacillus Calmette-Guérin (BCG) vaccine is ineffective in preventing adult pulmonary TB and affords no protection against latent TB infection (LTBI). Herein we investigated the potential of Mycobacterium tuberculosis (Mtb) antigen proteins AEC comprised of Ag85b and ESAT6-CFP10 proteins in conjunction with aluminum (Al) and polyriboinosinic-polyribocytidylic acid (poly-IC) as a novel subunit vaccine against TB. The immunogenicity and protection induced by the adjuvanted vaccine were evaluated in two animal models. Mice vaccinated with AEC/Al/poly-IC exhibited significant antigen-specific humoral immune responses and cell-mediated immunity as determined by immunoassay and multicolor flow cytometric assay, and the protective effect of the vaccine was demonstrated in a guinea pig model of latent Mtb infection. Compared to the control group, the mean pathological scores and bacterial loads in lungs and spleens of AEC/Al/poly-IC-immunized guinea pigs were significantly reduced. These data indicate that the AEC/Al/poly-IC is highly immunogenic in mice and can effectively protect guinea pigs against latent Mtb infection; it may represent a promising candidate vaccine for the control of latent TB.

Licensing the first reduced, 6 µg dose whole virion, aluminum adjuvanted seasonal influenza vaccine - A randomized-controlled multicenter trial.

INTRODUCTION: Shortages of vaccine supplies repeatedly occur, limiting our abilities to prevent influenza. Therefore, increasing production volume remains a priority. The presently licensed seasonal influenza vaccines contain 15 µg of viral hemagglutinin per strain in adult, and up to 60 µg in elderly patients. Decreasing the amount of viral parts while maintaining efficacy is one way of increasing production capacity. METHODS: This was multicenter, stratified (18-60 years and >60 years of age), prospective, randomized, double-blind, active-controlled, parallel-arm, non-inferiority clinical trial, conducted in the European Union, involving 1206 patients. We used hemagglutination inhibition assay to assess the immunogenicity of a newly developed, whole virion, seasonal trivalent influenza vaccine, containing 6 µg hemagglutinin per strain (FluArt, Hungary) and to assess whether it is non-inferior to the presently licensed vaccine containing 15 µg hemagglutinin per strain. Safety and tolerability of both vaccines were assessed based on EMEA guidelines. RESULTS: The reduced dose vaccine containing 6 µg of hemagglutinin per strain was safe and non-inferior to the currently licensed 15 µg vaccine, not only in adult, but also in elderly patients, according to the immunogenicity criteria by the FDA and EMEA (seroconversion, seroprotection and post/pre vaccination GMT ratios), and it fulfilled all applicable licensing requirements for both age groups. CONCLUSIONS: Based on the results, the reduced dose vaccine was licensed in the EU member state Hungary and safely administered in over 1.5 million cases so far. The amount of viral hemagglutinin needed can be reduced by using a whole virion vaccine with aluminum phosphate adjuvants. REGISTRATION: This study was registered by the European Clinical Trials Database, EudraCT, number: 2011-003314-16.

Macrophagic myofasciitis: a challenging diagnosis.

A 25-year-old man admitted for generalised muscle pain with an insidious onset 3 years ago. He had exercise intolerance and decrease in muscle strength, requiring gait support. He was previously healthy, with no chronic medication or recent history of drugs or toxics. National vaccination plan actualised with hepatitis B and tetanus vaccines administered 10 and 2 years, respectively, before symptom onset. No analytical, imaging or electromyography changes were found. Muscle biopsy revealed an inflammatory infiltrate predominantly macrophagic with aluminium deposits suggestive of macrophagic myofasciitis (MMF). It is probably associated with vaccines previously administered. MMF lesion can be regarded as pathological only if detected at least 18 months after last aluminic immunisation, as our case illustrates.

Atypical aluminium patch tests in children with persistent itching postvaccinal nodules.

Persistent itching nodules related to aluminium-adsorbed vaccines are well known in children with frequent positive patch tests to aluminium when tested. We report two cases of children with persistent postvaccination nodules who presented with atypical eruptions after aluminium patch tests.

Aluminum is a powerful adjuvant in teleost fish despite failing to induce interleukin-1ß release.

Although aluminum salts (Alum) have been extensively used in human vaccination for decades, its mechanism of action is controversial. In fish, the use of Alum as a vaccine adjuvant is scarce and there are no studies aimed at identifying its mechanism of action. In the present study we report that Alum is a powerful adjuvant in the gilthead seabream (Sparus aurata L., Sparidae) and the European seabass (Dicentrarchus labrax L. Moronidae). Thus, Alum increased the specific antibody titers to the model antigen keyhole limpet hemocyanin as the commonly used Freund's adjuvant did in both species. In addition, both adjuvants were able to increase the transcript levels of the gene encoding the major pro-inflammatory mediator interleukin-1ß (Il1b). Strikingly, however, Alum failed to promote Il1b release by seabream leukocytes and even impaired Il1b induction, processing and release in macrophages. However, it increased NADPH oxidase-dependent reactive oxygen species (ROS) production in gilthead seabream leukocytes and purified granulocytes. In addition, Alum promoted gilthead seabream leukocyte death independently of ROS production and caspases, suggesting that damage-associated molecular patterns release from dying cells mediate Alum adjuvant activity. Our results pave the way for future studies aimed at investigating the relevance of danger signals generated by Alum in vivo on its adjuvant activity in order to increase our understanding of the mechanisms of action of Alum in fish vaccines and to help in the design of new adjuvants for aquaculture.

Intraperitoneal administration of aluminium-based adjuvants produces severe transient systemic adverse events in mice.

Vaccines typically come with adjuvants that trigger the innate immune system in order to prepare best possible inflammatory conditions as to allow the adaptive immune system to become activated, generally for the induction of antibodies. The oldest approved and most abundant immunological adjuvants are salts of aluminium, which are also frequently used in animal models of immunisation and allergy desensitization. In rodents, the intraperitoneal administration of aluminium adjuvants is commonly performed and considered safe. In the current investigation, we show that intraperitoneal administration of aluminium adjuvants is associated with a dose-dependent hypothermic reaction within 10 min of the injection. The body temperature of mice dropped as much as 4 °C, and the clinical symptoms included apathy, hunched posture, and piloerection. The temperature normalised and other clinical manifestations disappeared within 60-80 min of the intraperitoneal aluminium injection, which caused strong infiltration of neutrophil and eosinophil granulocytes into the peritoneal cavity, a clinical manifestations typically associated with inflammasome activation. However, the observed reactions to aluminium adjuvants were independent of NALP3, caspase-1, and interleukin-1ß, but dependent on histamine. Hence, aluminium adjuvants may have potential local and systemic side effects, which warrants further investigations into the nature of these side effects, but also into the possible implications on health in man.

Stability of an aluminum salt-adjuvanted protein D-conjugated pneumococcal vaccine after exposure to subzero temperatures.

Accidental exposure of a vaccine containing an aluminum-salt adjuvant to temperatures below 0°C in the cold chain can lead to freeze damage. Our study evaluated the potential for freeze damage in a licensed aluminum-salt-containing protein-D-conjugated pneumococcal vaccine (PHiD-CV; Synflorix, GSK) in conditions that included static storage, single subzero-temperature excursions, and simulated air-freight transportation. Several parameters were assessed including freezing at subzero temperatures, aluminum-salt-particle size, antigen integrity and immunogenicity in the mouse. The suitability of the WHO's shake test for identifying freeze-damaged vaccines was also assessed. During subzero-temperature excursions, the mean temperatures at which PHiD-CV froze (-16.7°C to -18.1°C) appeared unaffected by the type of vaccine container (two-dose or four-dose vial, or single-dose syringe), vaccine batch, rotational agitation, or the rate of temperature decline (-0.5 to -10°C/hour). At constant subzero temperature and in simulated air-freight transportation, the freezing of PHiD-CV appeared to be promoted by vibration. At -5°C, no PHiD-CV sample froze in static storage (>1 month), whereas when subjected to vibration, a minority of samples froze (7/21, 33%) within 18 hours. At -8°C with vibration, nearly all (5/6, 83%) samples froze. In these vibration regimes, the shake test identified most samples that froze (10/12, 93%) except two in the -5°C regime. Nevertheless, PHiD-CV-antigen integrity appeared unaffected by freezing up to -20°C or by vibration. And although aluminum-salt-particle size was increased only by freezing at -20°C, PHiD-CV immunogenicity appeared only marginally affected by freezing at -20°C. Therefore, our study supports the use of the shake test to exclude freeze-damaged PHiD-CV in the field.

Adjuvants Enhancing Cross-Presentation by Dendritic Cells: The Key to More Effective Vaccines?

Over the last decades, vaccine development has advanced significantly in pursuing higher safety with less side effects. However, this is often accompanied by a reduction in vaccine immunogenicity and an increased dependency on adjuvants to enhance vaccine potency. Especially for diseases like cancer, it is important that therapeutic vaccines contain adjuvants that promote strong T cell responses. An important mode of action for such adjuvants is to prolong antigen exposure to dendritic cells (DCs) and to induce their maturation. These mature DCs are extremely effective in the activation of antigen-specific T cells, which is a pre-requisite for induction of potent and long-lasting cellular immunity. For the activation of CD8+ cytotoxic T cell responses, however, the exogenous vaccine antigens need to gain access to the endogenous MHCI presentation pathway of DCs, a process referred to as antigen cross-presentation. In this review, we will focus on recent insights in clinically relevant vaccine adjuvants that impact DC cross-presentation efficiency, including aluminum-based nanoparticles, saponin-based adjuvants, and Toll-like receptor ligands. Furthermore, we will discuss the importance of adjuvant combinations and highlight new developments in cancer vaccines. Understanding the mode of action of adjuvants in general and on antigen cross-presentation in DCs in particular will be important for the design of novel adjuvants as part of vaccines able to induce strong cellular immunity.

TLR8 combined withTLR3 or TLR4 agonists enhances DC-NK driven effector Tc1 cells.

BACKGROUND: Most current prophylactic vaccines confer protection primarily through humoral immunity. Indeed, aluminum salts which have been widely used as adjuvants in vaccines primarily enhance Th2-driven antibody responses. Therefore, new vaccines formulation is moving toward a careful selection of adjuvants that also elicit significant Th1 or Tc1 responses. Several TLR agonists have been tested as potential new adjuvants in clinical and preclinical studies with some efficacy. These studies suggest that combining more than one of TLR ligands enhances the magnitude of immune responses to cancer and infectious disease. OBJECTIVES: In order to evaluate the synergistic effect of TLR agonists for effective induction of cellular immunity, we investigated the effects of single and/or combined TLR agonists on monocyte-derived DC maturation, DC-NK crosstalk and ultimately naïve T cells polarization into effector T cells. RESULTS: Among the adjuvants tested, we found that TLR3, TLR4, TLR7/8 and TLR8 agonists were the most effective adjuvants to increase the expression levels of antigen-presenting, co-stimulatory molecules and production of cytokines by maturing DCs. When combined, TLR3+8 and TLR4+8 synergistically optimized DC maturation and IFN-γ secretion from NK cells co-cultured with DCs. Interestingly, co-culture of DC-NK-T treated with aluminum salt produced the highest percentage of effector memory CFSE-CCR7- Th1 cells whereas TLR3+8 and TLR4+8 treated co-cultures produced the highest percentage of effector memory CFSE-CCR7- Tc1 cells producing IFN-γ. Finally, while both TLR3+8 or TLR4+8 treated co-cultures generated similar frequency of Th1 and Tc1 effector cells, the effector cells from the latter co-culture produced quantitatively more IFN-γ in the supernatant. CONCLUSION: Our data indicate that if in need of an enhanced DC-NK mediated cellular immunity one may select TLR agonists with defined synergistic effects.

Sequestering of damage-associated molecular patterns (DAMPs): a possible mechanism affecting the immune-stimulating properties of aluminium adjuvants.

Aluminium-based adjuvants (ABAs) have been used in human and veterinary vaccines for decades, and for a long time, the adjuvant properties were believed to be mediated by an antigen depot at the injection site, prolonging antigen exposure to the immune system. The depot hypothesis is today more or less abandoned, and instead replaced by the assumption that ABAs induce an inflammation at the injection site. Induction of an inflammatory response is consistent with immune activation initiated by recognition of molecular patterns associated with danger or damage (DAMPs), and the latter are derived from endogenous molecules that normally reside intracellularly. When extracellularly expressed, because of damage, stress or cell death, a sterile inflammation is induced. In this paper, we report the induction of DAMP release by viable cells after phagocytosis of aluminium-based adjuvants. Two of the most commonly used ABAs in pharmaceutical vaccine formulations, aluminium oxyhydroxide and aluminium hydroxyphosphate, induced a vigorous extracellular expression of the two DAMP molecules calreticulin and HMGB1. Concomitantly, extracellular adjuvant particles adsorbed the DAMP molecules released by the cells whereas IL-1ß, a previously reported inflammatory mediator induced by ABAs, was not absorbed by the adjuvants. Induction of extracellular expression of the two DAMP molecules was more prominent using aluminium hydroxyphosphate compared to aluminium oxyhydroxide, whereas the extracellular adsorption of the DAMP molecules was more pronounced with the latter. Furthermore, it is hypothesised how induction of DAMP expression by ABAs and their concomitant adsorption by extracellular adjuvants may affect the inflammatory properties of ABAs.

Evidence Refuting the Existence of Autoimmune/Autoinflammatory Syndrome Induced by Adjuvants (ASIA).

Autoimmune/autoinflammatory syndrome induced by adjuvants (ASIA) was described in 2011. Over time the condition and its triggers have broadened to include several autoimmune disorders, the macrophagic myofasciitis syndrome, the Gulf war syndrome, the sick building syndrome, siliconosis, and the chronic fatigue syndrome. The aluminum-containing adjuvants in the hepatitis B vaccine and the human papillomavirus vaccine in particular have been stated to be the major causes of the disorder. Here, we review the specificity of the diagnostic criteria for ASIA. We also examine relevant human data, pertaining to causation, particularly from patients undergoing allergen-specific immunotherapy (IT). Patients undergoing allergen-specific IT receive 100 to 500 times more injected aluminum over 3 to 5 years, compared with hepatitis B and human papillomavirus vaccine recipients. In a large pharmacoepidemiological study, in contrast to case series of ASIA, patients receiving aluminum-containing allergen IT preparations were shown to have a lower incidence of autoimmune disease. In another clinical trial, there were no increases in exacerbations in a cohort of patients with systemic lupus erythematosus immunized with the hepatitis B vaccine. Current data do not support the causation of ASIA by vaccine adjuvants containing aluminum, which should be of reassurance to patients undergoing routine immunizations as well as to those undergoing allergen-specific IT.

Persistent Skin Reactions and Aluminium Hypersensitivity Induced by Childhood Vaccines.

There is increasing awareness of reactions to vaccination that include persistent skin reactions. We present here a retrospective investigation of long-lasting skin reactions and aluminium hypersensitivity in children, based on medical records and questionnaires sent to the parents. In the 10-year period 2003 to 2013 we identified 47 children with persistent skin reactions caused by childhood vaccinations. Most patients had a typical presentation of persisting pruritic subcutaneous nodules. Five children had a complex diagnostic process involving paediatricians, orthopaedics and plastic surgeons. Two patients had skin biopsies performed from their skin lesions, and 2 patients had the nodules surgically removed. Forty-two children had a patch-test performed with 2% aluminium chloride hexahydrate in petrolatum and 39 of them (92%) had a positive reaction. The persistent skin reactions were treated with potent topical corticosteroids and disappeared slowly. Although we advised families to continue vaccination of their children, one-third of parents omitted or postponed further vaccinations.

[Aluminium allergy and granulomas induced by vaccinations for children]. / Aluminiumallergi og granulomer som følge af vaccination hos børn.

Vaccination with aluminium-adsorbed vaccines can induce aluminium allergy with persistent itching subcutaneous nodules at the injection site ­ vaccination granulomas. In this article we give an overview of childhood aluminium-adsorbed vaccines available in Denmark. Through literature studies we examine the incidence, the symptoms and the prognosis for the vaccination granulomas and the allergy. Finally we discuss the status in Denmark.

Decennial administration in young adults of a reduced-antigen content diphtheria, tetanus, acellular pertussis vaccine containing two different concentrations of aluminium.

BACKGROUND: Regular booster vaccination might be necessary throughout life to protect against pertussis infection. Nevertheless the duration of protection after booster vaccination remains unclear. In this study, antibody persistence up to 10 years after previous vaccination of adolescents (N=478) with combined reduced-antigen-content diphtheria-tetanus-acellular pertussis vaccine (dTpa, Boostrix™, GlaxoSmithKline Belgium) containing 0.5mg, 0.3mg or 0.133mg of aluminium was assessed. The immunogenicity, reactogenicity and safety of a decennial booster dTpa dose were also investigated. METHODS: Young adults vaccinated as adolescents in the initial booster study were invited to participate in an assessment of antibody persistence at years 8.5 and 10, and to receive a dTpa booster dose at year 10 with immunogenicity assessment one month later. Those who originally received the 0.5mg or 0.3mg formulations received the same vaccine at year 10. Those in the 0.133mg group received the 0.5mg formulation. Reactogenicity and safety endpoints were captured until 30 days after booster vaccination. RESULTS: Prior to the decennial booster at year 8.5 and year 10, all participants had seroprotective antibodies for diphtheria (ELISA or neutralisation assay) and tetanus. At least 77.8% were seropositive for anti-pertussis toxin (PT) antibodies at year 8.5 and 82.8% at year 10. All participants were seropositive for antibodies for filamentous haemagglutinin and pertactin at both time points. The decennial booster dose induced robust increases in antibody GMCs to all antigens. The post-booster anti-PT geometric mean concentration was 82.5EL.U/ml (95%CI 67.0-101.6) and 124.0 (103.5-148.5) in the 0.3mg and 0.5mg groups, respectively. The reactogenicity and safety profile of the decennial booster dose was consistent with the known safety profile of dTpa. No serious adverse events were reported. CONCLUSIONS: Decennial booster vaccination with either of the two licensed formulations of dTpa was highly immunogenic and well tolerated in young adults. Either formulation could be confidently used as a decennial booster. This study is registered at www.clinicaltrials.govNCT01147900.

Long-term immunogenicity of an inactivated split-virion 2009 pandemic influenza A H1N1 virus vaccine with or without aluminum adjuvant in mice.

In 2009, a global epidemic of influenza A(H1N1) virus caused the death of tens of thousands of people. Vaccination is the most effective means of controlling an epidemic of influenza and reducing the mortality rate. In this study, the long-term immunogenicity of influenza A/California/7/2009 (H1N1) split vaccine was observed as long as 15 months (450 days) after immunization in a mouse model. Female BALB/c mice were immunized intraperitoneally with different doses of aluminum-adjuvanted vaccine. The mice were challenged with a lethal dose (10× 50% lethal dose [LD(50)]) of homologous virus 450 days after immunization. The results showed that the supplemented aluminum adjuvant not only effectively enhanced the protective effect of the vaccine but also reduced the immunizing dose of the vaccine. In addition, the aluminum adjuvant enhanced the IgG antibody level of mice immunized with the H1N1 split vaccine. The IgG level was correlated to the survival rate of the mice. Aluminum-adjuvanted inactivated split-virion 2009 pandemic influenza A H1N1 vaccine has good immunogenicity and provided long-term protection against lethal influenza virus challenge in mice.

[Aluminium allergy and granulomas induced by vaccinations for children].

Vaccination with aluminium-adsorbed vaccines can induce aluminium allergy with persistent itching subcutaneous nodules at the injection site - vaccination granulomas. In this article we give an overview of childhood aluminium-adsorbed vaccines available in Denmark. Through literature studies we examine the incidence, the symptoms and the prognosis for the vaccination granulomas and the allergy. Finally we discuss the status in Denmark.

Metal sensitivities among TJA patients with post-operative pain: indications for multi-metal LTT testing.

Metal sensitivity testing is generally the diagnosis method of last resort for aseptic painful implants with elevated inflammatory responses. However, the relationship between implant-related pain and implant-debris-related metal sensitization remains incompletely understood. Although a sensitivity to nickel alone has been used as a general measure of metal allergy, it may lack the specificity to correlate sensitivity to specific implant metals and thus to select a biologically appropriate implant material. In this retrospective study, we report the incidence of pain and nickel sensitivity in patients with total joint arthroplasties (TJAs) referred for metal sensitivity testing (n=2018). We also correlated the degree of nickel hypersensitivity to implant pain levels (none, mild, moderate, and high, using a scale of 0-10) and the incidence of sensitivity to alternative implant metals in highly nickel-reactive subjects. Most patients (>79%) reported pain levels that were moderate to high regardless of implant age, whereas patients with severely painful TJAs had a statistically greater incidence of nickel sensitivity over the short-term post-operative period (≤4 years). Patients with moderate pain scores (4-7) and high pain scores (≥8) also exhibited significantly higher sensitivity to nickel compared to patients with no pain and no implant (controls) (p<0.05). Highly nickel-sensitive subjects (SI>8) also showed incidences of sensitization to alternative materials such as cobalt, chromium, or molybdenum (57%) or aluminum or vanadium alloy (52%). These data suggest that painful TJAs caused by metal sensitivity more likely occur relatively early in the post-operative period (≤4 years). The incidences of sensitivity to alternative implant metals in only a subset of nickel-reactive patients highlights the importance of testing for sensitization to all potential revision implant materials.