Metal sensitivity in patients with orthopaedic implants: a prospective study

Somatoform and neurocognitive syndromes after HPV immunization are not associated to cell-mediated hypersensitivity to aluminum

Vaccines against human papilloma virus (HPV) have been demonstrated to be very effective to prevent infection-related neoplasms. However, several reports describing heterogeneous post-vaccination phenomena have been published in last few years. The spectrum of these disorders includes both immune-mediated neurological diseases and neuropsychiatric functional disorders. Some researchers speculated about a genetic predisposition, but others hypothesized a role of adjuvants, including some metals and, particularly, aluminum. Here, we tested sixteen young girls developing somatoform and neurocognitive syndromes after the HPV immunization, through MELISA® test, detecting cell-mediated hypersensitivity to several metals. We found no association between these neurocognitive disorders and the results provided by this test; importantly, no patients showed hypersensitivity to aluminum, which is the inorganic adjuvant included in HPV vaccines. Thus, if aluminum played a role in the pathophysiology of musculoskeletal and neurocognitive disturbances occurring in some young girls after HPV immunization, that should recognize other mechanisms than the activation of aluminum-specific lymphocytes.

Hypersensitivity to Orthopedic Implants: A Review of the Literature

Awareness of rare etiologies for implant failure is becoming increasingly important. In addition to the overall increase in joint arthroplasties, revision surgeries are projected to increase dramatically in the coming years, with volume increasing up to seven-fold between 2005 and 2030. The literature regarding the relationship between metal allergy and implant failure is controversial. It has proven difficult to determine whether sensitization is a cause or a consequence of implant failure. Testing patients with functional implants is not a clinically useful approach, as the rate of hypersensitivity is higher in implant recipients than in the general population, regardless of the status of the implant. As a result of the ineffectiveness of preoperative patch testing for predicting adverse outcomes, as well as the high cost of implementing such patch testing as standard procedure, most orthopedists and dermatologists agree that an alternative prosthesis should only be considered for patients with a history of allergy to a metal in the standard implant. In patients with a failed implant requiring revision surgery, hypersensitivity to an implant component should be considered in the differential diagnosis. Because a metal allergy to implant components is currently not commonly considered in the differential for joint failure in the orthopedic literature, there should be improved communication and collaboration between orthopedists and dermatologists when evaluating joint replacement patients with a presentation suggestive of allergy.

Laser surface modification of 316L stainless steel

Medical grade 316L stainless steel was laser surface melted (LSM) using continuous wave Nd-YAG laser in argon atmosphere at 1 and 5 mm/s. The treated surfaces were characterized using electron backscatter diffraction to study the influence of top surface crystallographic orientation and type of grain boundaries on corrosion resistance, wettability, and biocompatibility. The laser scan velocity was found to have a marginal influence on the surface roughness and the type of grain boundaries. However, the crystal orientation density was found to be relatively high in 1 mm/s samples. The LSM samples showed a higher concentration of {101} and {123} planes parallel to the sample surface as well as a higher fraction of low-angle grain boundaries. The LSM samples were found to exhibit better surface wettability and enhanced the viability and proliferation of human fetal osteoblast cells in vitro when compared to the untreated samples. Further, the corrosion protection efficiency of 316L stainless steel was improved up to 70% by LSM in as-processed condition. The increased concentration of {101} and {123} planes on surfaces of LSM samples increases their surface energy, which is believed to be responsible for the improved in vitro cell proliferation. Further, the increased lattice spacing of these planes and high concentration of low-energy grain boundaries in LSM samples would have contributed to the better in vitro corrosion resistance than untreated 316L stainless steel. Our results indicate that LSM can be a potential treatment option for 316L stainless steel-based biomedical devices to improve biocompatibility and corrosion resistance. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 569-577, 2018.

Allergies in orthopaedic and trauma surgery

Hypersensitivity reactions to implants in orthopaedic and trauma surgery are a rare but devastating complication. They are considered as a delayed-type of hypersensitivity reaction (type IV), characterized by an antigen activation of sensitized T-lymphocytes releasing various cytokines and may result in osteoclast activation and bone resorption. Potential haptens are originated from metal alloys or bone-cement. A meta-analysis has confirmed a higher probability of developing a metal hypersensitivity postoperatively and noted a greater risk of failed replacements compared to stable implants. Hypersensitivity to implants may present with a variety of symptoms such as pain, joint effusion, delayed wound/bone healing, persistent secretion, allergic dermatitis (localized or systemic), clicking noises, loss of joint function, instability and failure of the implant. Various diagnostic options have been offered, including patch testing, metal alloy patch testing, histology, lymphocyte transformation test (LTT), memory lymphocyte immunostimulation assay (MELISA), leukocyte migration inhibition test (LIF) and lymphocyte activation test (LAT). No significant differences between in vivo and in vitro methods have been found. Due to unconvincing evidence for screening methods, predictive tests are not recommended for routine performance. Infectious aetiology always needs to be excluded. As there is a lack of evidence on large-scale studies with regards to the optimal treatment option, management currently relies on individual case-by-case decisions. Several options for patients with (suspected) metal-related hypersensitivity exist and may include materials based on ceramic, titanium or oxinium or modified surfaces. Promising results have been reported, but long-term experience is lacking. More large-scaled studies are needed in this context. In patients with bone-cement hypersensitivity, the component suspected for hypersensitivity should be avoided. The development of (predictive) biomarkers is considered as a major contribution for the future.

Allergy in Total Knee Replacement. Does It Exist?: Review Article

BACKGROUND

There is little data on whether preexisting allergies to implant materials and bone cement have an impact on the outcome of TKA.

QUESTIONS/PURPOSES

This review article analyzes the current literature to evaluate the prevalence and importance of metal and cement allergies for patients undergoing total knee arthroplasty.

METHODS

A review of the literature was performed using the following search criteria: "knee," "arthroplasty," and "allergy" as well as "knee," "arthroplasty," and "hypersensitivity."

RESULTS

One hundred sixteen articles were identified on PubMed, Seventy articles could be excluded by reviewing the title and abstract leaving 46 articles to be included for this review. The majority of the studies cited patch testing as the gold standard for screening and diagnosis of hypersensitivity following TKA. There is consensus that patients with self-reported allergies against metals or bone cement and positive patch test should be treated with hypoallergenic materials or cementless TKA. Treatment options include the following: coated titanium or cobalt-chromium implants, ceramic, or zirconium oxide implants.

CONCLUSION

Allergies against implant materials and bone cement are rare. Patch testing is recommended for patients with self-reported allergies. The use of special implants is recommended for patients with a confirmed allergy.

Availability of Total Knee Arthroplasty Implants for Metal Hypersensitivity Patients

Purpose

To provide information on the type of "hypersensitivity-friendly" components available for primary total knee arthroplasty (TKA) in the current market.

Materials and Methods

Implant manufactures were identified using the 2013 National Joint Registries of the United Kingdom and Sweden and contacted to obtain information about the products they offer for patients with metal hypersensitivity.

Results

Information on 23 TKA systems was provided by 13 implant manufacturers. Of these, 15 systems had options suitable for metal hypersensitivity patients. Two types of "hypersensitivity-friendly" components were identified: 10 implants were cobalt chrome prostheses with a "hypersensitivity-friendly" outer coating and 5 implants were made entirely from non-cobalt chrome alloys.

Conclusions

The results of this study suggest that several hypersensitivity TKA options exist, some of which provide the same designs and surgical techniques as the conventional implants. The information in this study can guide TKA surgeons in making informed choices about implants and identifying implants that could be examined in future controlled studies comparing outcomes between "hypersensitivity-friendly" and conventional implants.

Quantitative in vivo biocompatibility of new ultralow-nickel cobalt-chromium-molybdenum alloys

Nickel (Ni) eluted from metallic biomaterials is widely accepted as a major cause of allergies and inflammation. To improve the safety of cobalt-chromium-molybdenum (Co-Cr-Mo) alloy implants, new ultralow-Ni Co-Cr-Mo alloys with and without zirconium (Zr) have been developed, with Ni contents of less than 0.01%. In the present study, we investigated the biocompatibility of these new alloys in vivo by subcutaneously implanting pure Ni, conventional Co-Cr-Mo, ultralow-Ni Co-Cr-Mo, and ultralow-Ni Co-Cr-Mo with Zr wires into the dorsal sides of mice. After 3 and 7 days, tissues around the wire were excised, and inflammation; the expression of IL-1β, IL-6, and TNF-α; and Ni, Co, Cr, and Mo ion release were analyzed using histological analyses, qRT-PCR, and inductively coupled plasma mass spectrometry (ICP-MS), respectively. Significantly larger amounts of Ni eluted from pure Ni wires than from the other wires, and the degree of inflammation depended on the amount of eluted Ni. Although no significant differences in inflammatory reactions were identified among new alloys and conventional Co-Cr-Mo alloys in histological and qRT-PCR analyses, ICP-MS analysis revealed that Ni ion elution from ultralow-Ni Co-Cr-Mo alloys with and without Zr was significantly lower than from conventional Co-Cr-Mo alloys. Our study, suggests that the present ultralow-Ni Co-Cr-Mo alloys with and without Zr have greater safety and utility than conventional Co-Cr-Mo alloys. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1505-1513, 2016.

Midterm Results After Coated and Uncoated TKA: A Randomized Controlled Study

Patients undergoing total knee arthroplasty (TKA) who have hypersensitivity to metals usually receive hypoallergenic TKA implants. Coating of a standard implant is a common solution. Although in vitro tests have demonstrated reduction in polyethylene wear for these coatings, it is unknown whether these costly implants have a clinical benefit for patients. One hundred twenty patients undergoing TKA were randomly assigned to receive a novel 7-layer-coating implant or a standard TKA implant. One revision occurred in the standard group, resulting in a calculated 5-year survival of 100% in the coated group and 98.1% in the standard group. The Oxford Knee Score improved substantially in both groups from a mean of 21.6 points preoperatively in the coated group and 21.9 points in the standard group to 39.2 points and 39.2 points, respectively. The current authors observed no adverse effects with the new coating during midterm follow-up. However, longer follow-up time is needed to evaluate possible advantages of this coating. [Orthopedics. 2016; 39(3):S13-S17.].

Titanium: a review on exposure, release, penetration, allergy, epidemiology, and clinical reactivity

Exposure to titanium (Ti) from implants and from personal care products as nanoparticles (NPs) is common. This article reviews exposure sources, ion release, skin penetration, allergenic effects, and diagnostic possibilities. We conclude that human exposure to Ti mainly derives from dental and medical implants, personal care products, and foods. Despite being considered to be highly biocompatible relative to other metals, Ti is released in the presence of biological fluids and tissue, especially under certain circumstances, which seem to be more likely with regard to dental implants. Although most of the studies reviewed have important limitations, Ti seems not to penetrate a competent skin barrier, either as pure Ti, alloy, or as Ti oxide NPs. However, there are some indications of Ti penetration through the oral mucosa. We conclude that patch testing with the available Ti preparations for detection of type IV hypersensitivity is currently inadequate for Ti. Although several other methods for contact allergy detection have been suggested, including lymphocyte stimulation tests, none has yet been generally accepted, and the diagnosis of Ti allergy is therefore still based primarily on clinical evaluation. Reports on clinical allergy and adverse events have rarely been published. Whether this is because of unawareness of possible adverse reactions to this specific metal, difficulties in detection methods, or the metal actually being relatively safe to use, is still unresolved.

Titanium niobium nitride knee implants are not inferior to chrome cobalt components for primary total knee arthroplasty

BACKGROUND

Metal allergy in total knee arthroplasty (TKA) is still a controversial topic. Oxinium, ceramic or titanium niobium nitride (TiNbN) coated implants are available for some knee systems. The hypothesis of this study was that the use of TiNbN-coated components would not lead to inferior results compared to conventional implants and that none of the allergic patients receiving TiNbN-coated implants would require revision for metal allergy.

MATERIALS AND METHODS

This study was a retrospective, 2 to 1 matched pairs study with 40 titanium niobium nitride-coated TKA compared with 80 conventional cobalt chrome implants. No demographic differences between these groups were observed. The mean follow-up for this study was 2 years.

RESULTS

No differences in clinical, radiological, or patient-reported outcome measurements were observed between the two groups. No patients have been revised at this short- to medium-term outcome evaluation.

DISCUSSION

Metal allergy leading to contact or systemic dermatitis is especially linked to chrome and cobalt allergy. Nickel allergy because of knee implants rarely gives cutaneous symptoms, but could potentially lead to peri-prosthetic osteolysis and loosening. The use of titanium niobium nitride implants in case of a positive history of metal allergy could avoid this devastating complication.

CONCLUSION

The use of titanium niobium nitride-coated implants for primary knee osteoarthritis shows similar clinical and radiological outcomes as conventional TKA without revision for loosening at short- to medium-term follow-up. Level of evidence Level IV study.

The association between metal allergy, total knee arthroplasty, and revision: study based on the Danish Knee Arthroplasty Register

BACKGROUND AND PURPOSE

It is unclear whether delayed-type hypersensitivity reactions against implanted metals play a role in the etiopathogenesis of malfunctioning total knee arthroplasties. We therefore evaluated the association between metal allergy, defined as a positive patch test reaction to common metal allergens, and revision surgery in patients who underwent knee arthroplasty.

PATIENTS AND METHODS

The nationwide Danish Knee Arthroplasty Register, including all knee-implanted patients and revisions in Denmark after 1997 (n = 46,407), was crosslinked with a contact allergy patch test database from the greater Copenhagen area (n = 27,020).

RESULTS

327 patients were registered in both databases. The prevalence of contact allergy to nickel, chromium, and cobalt was comparable in patients with and without revision surgery. However, in patients with 2 or more episodes of revision surgery, the prevalence of cobalt and chromium allergy was markedly higher. Metal allergy that was diagnosed before implant surgery appeared not to increase the risk of implant failure and revision surgery.

INTERPRETATION

While we could not confirm that a positive patch test reaction to common metals is associated with complications and revision surgery after knee arthroplasty, metal allergy may be a contributor to the multifactorial pathogenesis of implant failure in some cases. In cases with multiple revisions, cobalt and chromium allergies appear to be more frequent.

Biomaterial hypersensitivity: is it real? Supportive evidence and approach considerations for metal allergic patients following total knee arthroplasty

The prospect of biomaterial hypersensitivity developing in response to joint implant materials was first presented more than 30 years ago. Many studies have established probable causation between first-generation metal-on-metal hip implants and hypersensitivity reactions. In a limited patient population, implant failure may ultimately be related to metal hypersensitivity. The examination of hypersensitivity reactions in current-generation metal-on-metal knee implants is comparatively limited. The purpose of this study is to summarize all available literature regarding biomaterial hypersensitivity after total knee arthroplasty, elucidate overall trends about this topic in the current literature, and provide a foundation for clinical approach considerations when biomaterial hypersensitivity is suspected.

Metal hypersensitivity in patient with posterior lumbar spine fusion: a case report and its literature review

BACKGROUND

Metal hypersensitivity, mostly documented in prosthesis implantation, is a rare complication after arthroplasty. Such cases become rarer and more difficult to diagnose when it comes to lumbar surgery.

CASE PRESENTATION

We present the case of a 52-year-old female patient with reoccured low back pain and sciatica after posterior lumbar decompression and fusion (PLDF) for her lumbar disc herniation. The initial clinical and radiological examinations showed no pathologies. Further imaging and histopathological studies in later period revealed an aseptic loosening of the hardware and an aseptic inflammatory response which was diagnosed to be metal hypersensitivity. To our knowledge, few allergic cases in the matter of spinal fusion were reported so far.

CONCLUSIONS

Metal hypersensitivity after spinal fusion should be considered in patients with representation of postoperative back pain. And elaborate history taking would conduce a lot to it's diagnose.

Metal hypersensitivity in total joint arthroplasty

OBJECTIVE

To review the clinical manifestations, testing methods, and treatment options for hypersensitivity reactions to total joint arthroplasty procedures.

DATA SOURCES

Studies were identified using MEDLINE and reference lists of key articles.

STUDY SELECTIONS

Randomized controlled trials were selected when available. Systematic reviews and meta-analyses of peer-reviewed literature were included, as were case series and observational studies of clinical interest.

RESULTS

Total joint arthroplasty procedures are increasing, as are the hypersensitivity reactions to these implants. Evidence is not conclusive as to whether metal joint implants increase metal sensitivity or whether metal sensitivity leads to prosthesis failure. Currently, patch testing is still the most widely used method for determining metal hypersensitivity; however, there are no standardized commercial panels specific for total joint replacements available currently. In vitro testing has shown comparable results in some studies, but its use in the clinical setting may be limited by the cost and need for specialized laboratories. Hypersensitivity testing is generally recommended before surgery for patients with a reported history of metal sensitivity. In cases of metal hypersensitivity-related joint failure, surgical revision ultimately may be required. Knowledge about joint replacement hypersensitivity reactions becomes vital because the approach to the evaluation depends on appropriate testing to guide recommendations for future arthroplasty procedures.

CONCLUSION

Evaluation of hypersensitivity reactions after total joint arthroplasty requires a systematic approach, including a careful history, targeted evaluation with skin testing, and in vitro studies.

Strong association between smoking and the risk of revision in a cohort study of patients with metal-on-metal total hip arthroplasty

Thus far the ability to predict who will develop early failure following the insertion of a metal-on-metal (MoM) bearing has been very limited. Our objective was to assess the effect of smoking on failure rates in patients with MoM bearing, compared with patients with ceramic-on-polyethylene (CoP) bearing. From a prospective hospital-based registry we included all primary THAs operated upon between 1/2001 and 12/2011 with MoM or CoP bearings of the same cup design and head size (28 mm). We compared revision rates through 10/2013 classified by smoking status and type of bearing. We included 1,964 patients (median age 71, 57% women), 663 with MoM and 1,301 with CoP bearing. Mean follow-up was 6.9 years (range 1.8-12.8). Revisions were required for 56 THAs. In patients with MoM bearing the adjusted incidence rate of revision among ever-smokers was four times greater than among never-smokers (95% CI 1.4-10.9). Among those with CoP bearing, the rate ratio was only 1.3 (95% CI 0.6-2.5). We found a strong association between smoking and increased failure of MoM THAs. In contrast, the association was weak for patients with CoP bearing. Smoking might be a trigger or an effect amplifier for adverse reactions to metal debris from MoM bearings.

Systemic contact dermatitis and allergy to biomedical devices

Systemic contact dermatitis (SCD) refers to a skin condition where an individual who is cutaneously sensitized to an allergen will subsequently react to that same allergen or a cross-reacting allergen via the systemic route. It occurs to allergens including metals, medications, and foods. There has been recent interest in metal allergy as it relates to the implantation of devices such as orthopedic, dental, cardiac, and gynecologic implants. This review will briefly address all causes of systemic contact dermatitis with a special and expanded focus on metal implant allergy. We present literature on SCD to various metal biomedical devices, patch testing for diagnosis of metal allergy pre and post implantation and treatment.

Metal hypersensitivity and metal ion levels in patients with coated or uncoated total knee arthroplasty: a randomised controlled study

PURPOSE

Metal ion release by orthopaedic implants may cause local and systemic effects and induce hypersensitivity reactions. Coated implants have been developed to prevent or reduce these effects. This study was initiated to investigate the safety of a novel coating for total knee arthroplasty (TKA) implants.

METHODS

A total of 120 patients undergoing primary TKA with no history of hypersensitivity and no other metal implant were randomised to receive either a coated or uncoated implant. Chromium (Cr), cobalt (Co), molybdenum (Mb) and nickel (Ni) hypersensitivity patch testing and plasma ion concentrations were evaluated pre-operatively and one year post-operatively.

RESULTS

At the one year follow-up both groups demonstrated significant improvement in knee function and quality of life. One new weakly positive reaction to Co in the TKA group with coated implant and two doubtful skin reactions to Ni (one in each group) were noted. Even with sensitisation to implant materials no skin reactions were observed. Plasma metal ion concentrations did not increase and were not elevated at the one year follow-up in either group.

CONCLUSIONS

Sensitisation after TKA was rare and had no influence on clinical results. TKA with coated implant and standard TKA demonstrated no plasma metal ion elevation.

The effects on bone cells of metal ions released from orthopaedic implants. A review

The increasing use of orthopedic implants and, in particular, of hip and knee joint replacements for young and active patients, has stimulated interest and concern regarding the chronic, long-term effects of the materials used. This review focuses on the current knowledge of the adverse biologic reactions to metal particles released from orthopaedic implants in vivo and in vitro. More specifically, the purpose of this article is to provide an overview of the current literature about the adverse effects of metal particles on bone cells and peri-implant bone.

Prospective analysis of human leukocyte functional tests reveals metal sensitivity in patients with hip implant

Background

The aim of the study was to examine the reactivity of peripheral human leukocytes to various metal ions prior and following hip replacement in order to investigate implant-induced metal sensitivity.

Methods

Three patient groups were set up: (1) individuals without implants and no history of metal allergy (7 cases), (2) individuals without implants and known history of metal allergy (7 cases), and (3) patients undergoing cementless hip replacement (40 cases). Blood samples were taken in groups 1 and 2 at three different occasions; in group 3, prior and 3, 6, 12, 24, and 36 months after surgery. Peripheral leukocytes were separated and left either untreated or challenged with Ti, NiCl₂, CoCl₂, CrCl₃, and phytohemagglutinin. Cell proliferation, cytokine release, and leukocyte migration inhibition assays were performed. Metal-induced reactivity was considered when all three assays showed significant change. Skin patch tests were also carried out.

Results

Both skin patch tests and leukocyte functional tests were negative in group 1, and both were positive in group 2. In group 3, after 6 months, 12% of the patients showed reactivity to the tested metals except for NiCl₂. Following the 36-month period, 18% of group three became sensitive to metals (including all the earlier 12%). In contrast, patch tests were negative at each time point in group 3.

Conclusions

Orthopedic implant material may induce metal reactivity after implantation in a manner where susceptibility is yet to be elucidated. Leukocyte triple assay technique might be a useful tool to test implant material-related sensitivity.

No allergic reaction after TKA in a chrome-cobalt-nickel-sensitive patient: case report and review of the literature

Hypersensitivity to metallic implants remains relatively unpredictable and poorly understood. Although 20-25 % of total joint arthroplasty patients develop metal sensitivity, only a few highly susceptible persons (<1 %) exhibit symptoms. We present a case report of a fifty-two-year-old woman with a preoperatively documented metal allergy who underwent bilateral total knee arthroplasty using a titanium-niobium-coated implant on one side and a chrome-cobalt implant on the other side because of a logistics problem. At 2-year follow-up, no clinical symptoms of allergy or loosening of the implant were observed. Level of evidence IV.

Metal hypersensitivity testing in patients undergoing joint replacement: a systematic review

We report a systematic review and meta-analysis of the peer-reviewed literature focusing on metal sensitivity testing in patients undergoing total joint replacement (TJR). Our purpose was to assess the risk of developing metal hypersensitivity post-operatively and its relationship with outcome and to investigate the advantages of performing hypersensitivity testing. We undertook a comprehensive search of the citations quoted in PubMed and EMBASE: 22 articles (comprising 3634 patients) met the inclusion criteria. The frequency of positive tests increased after TJR, especially in patients with implant failure or a metal-on-metal coupling. The probability of developing a metal allergy was higher post-operatively (odds ratio (OR) 1.52 (95% confidence interval (CI) 1.06 to 2.31)), and the risk was further increased when failed implants were compared with stable TJRs (OR 2.76 (95% CI 1.14 to 6.70)). Hypersensitivity testing was not able to discriminate between stable and failed TJRs, as its predictive value was not statistically proven. However, it is generally thought that hypersensitivity testing should be performed in patients with a history of metal allergy and in failed TJRs, especially with metal-on-metal implants and when the cause of the loosening is doubtful.

The role of lymphocyte proliferation tests in assessing occupational sensitization and disease

PURPOSE OF REVIEW

Lymphocyte proliferation testing (LPT) is used in diagnosing occupationally acquired delayed-type hypersensitivity. It has been used in beryllium-health effects, and its role is expanding in metal allergy. It may find application in diagnosis of other sensitizers.

RECENT FINDINGS

Use of the beryllium LPT (BeLPT) in medical surveillance identifies beryllium sensitization at low exposure with chronic beryllium disease (CBD) that leads to physiologic impairment and need for immunosuppressive medications. New studies indicate that both beryllium exposure and genetic variation are associated with increased risk of CBD. Borderline positive BeLPTs warrant inclusion into diagnostic algorithms. Furthermore, use of LPTs to diagnose metal allergy is being proposed in diagnosis of chromium allergy and hypersensitivity to surgical implants. New occupational sensitizers continue to be identified including metalworking fluids, the sterilizing agent ortho-phthalaldehyde and the solvent para-chlorobenzotrifluoride. Use of LPT in occupational surveillance to these agents and other known sensitizers may play expanding roles.

SUMMARY

Lymphocyte proliferation testing serves a valuable role in diagnosing occupational sensitization, as demonstrated with beryllium-health effects, as cases continue to be found at low exposure levels. The use of LPTs in diagnosing contact allergy is expanding, and new applications may be identified in human and animal studies.