- Email: [email protected]
HLA ANTIBODIES DETECTED BY ELISA HTLV-III ANTIBODY KITS
397 HLA ANTIBODIES DETECTED BY ELISA HTLV-III ANTIBODY KITS
SiR.—Dr Kuhnl and colleagues (May 25, p 1222) provide evidence that HLA-DR4 antibodies may give positive results in enzyme-linked immunosorbent assays (ELISA) used to detect antibodies to human T-cell lymphotropic virus type III (HTLV-III). 10 of 27 (37%) DR4 alloantisera were positive in the ELISA. The 10 monoclonal antisera were ELISA negative; however, this is expected since the second antibody, anti-human IgG, would not react with the mouse monoclonals even if they bound to the bead. The data suggest that HLA-DR4 antigen is present on the test beads used in the ELISA and, therefore, on H9, the cell line from which viral antigen is isolated for use in commercially available test kits. Professor Weiss and colleagues (July 20, p 156) typed H9 and confirmed the presence ofDR4 as well as HLA Al, Bw62, Bw6, Cw3, and DQw3. To examine whether the ELISA positives are caused by DR4 antibodies, we tested HLA antisera, procured locally from multiparous women, with Abbott ELISA kits. Class I antisera directed against HLA A, B, C found on H9 and DR antisera specific for non-H9 associated specificities were ELISA negative. 1 of 5 antiDR4 and 3/4 anti-DQw3 sera were reproducibly ELISA positive. All sera tested were negative for HTLV-III antibodies by western blot. To extend the evidence that not only DR4 but also DQw3 antibodies give positive results in HTLV-111 ELISA tests we did HLA antibody analysis on sera from 20 ELISA repeatedly reactive blood donors. 6 of the donors were also HTLV-111 antibody positive by western blot. 4 of the 20 sera have DQw3 or DR4 specificity and an additional 5 reacted with some DR4 and DQw3 cells: for HTL h111 antibody positive/western blot negative (n== 14) ELISA positive/western blot positive (n=6)
Anll-HLA
Donors pOSlln’e
ELISA
speciflcltzes detected DQw3, 1 DR4, 1 DQwl, non-specific,* 9 negative DQw3, 1 A9+,* 3 non-specific,* 2 1
1
*
sensitivity and specificity and upon the likelihood of the disease being present. Even for a very sensitive and specific test, a single positive finding, such as deltoid atrophy or a positive Adson’s manoeuvre, is more likely to represent a false positive than true disease, if the clinical picture suggests that the disease is unlikely. Clinicians should also recognise that their judgment may be affected by the priority they place on making a diagnosis. A physician who thinks that making a diagnosis is all-important may zealously pursue a diagnosis "because it is there"’ or may follow the maxim "when in doubt make a diagnosis".The attitude that it is much worse to call a sick person well, than to call a well person sick is deeply engrained in the medical profession and is supported by legal sanction (especially in the USA).3This attitude underlies the "minimax" decision strategy or "better safe than sorry" approach, through which the doctor aims to minimise the chances of maximum possible loss or the worst outcome by directing investigation towards the most serious, though improbable, diagnosis.4All these biases in decision making may result in overdiagnosis or
misdiagnosis. As Jenkins implies, his patient and the community would have been better served if the physicians involved had recognised the limitations of their tests and curbed their desires to make a diagnosis. As family physicians we would have liked to know how the patient reacted to the revelation of his fitness and what the final outcome was.
Department of Family Medicine, University of Western Ontario, London, Ontario, Canada N6A 5C I 1 Editorial.
Iatrogenesis Just what the
MARTIN J. BASS ROGER P. STRASSER doctor
ordered. J Community
Health 1980, 5:
149-57. 2 Wulff HR Rational diagnosis and treatment Oxford Blackwell, 1976: 114 3 Reiser SJ Medicine and the reign of technology Cambridge Cambridge University Press, 1978, 192 4 Bursztajn H, Feinbloom RI, Hamm RM, Brodsky A Medical choices, medical chances New York: Merloyd Lawrence, 1981 189-90
1 negative
*Reactivity not sufficient to assign specificity; however, sera preferentially reacted with DQw3 positive B cells These data indicate that reactivity in HTLV-III ELISA assays can
DIFFUSE HYPEROSTOSIS ASSOCIATED WITH ETRETINATE
be due to DR4 and also DQw3 antibodies. However, we agree with Weiss et al that HLA antibody evaluation does not distinguish false positive ELISA results since one of our 6 western blot positive donors also has anti-DQw3 and 3 have non-specific class II HLA
SIR,-The retinoids are now the drugs of choice for the management of severe disorders of keratin is at ion such as ichthyosis. Isotretinoin (’Accutane’) has been used widely in the United States,
DR4 and
antibody. Western blot results are currently used for verification of HTLVIII antibodies detected by ELISA. The validity of this approach is supported by our finding that none of the HLA typing sera were positive by western blot and that 89% of western blot positive donors reported in the US by the Council of Community Blood Centers are males. Nevertheless, there is an urgent need to confirm this assumption by viral cultures or HTLV-III antigen specific testing. In addition, we strongly urge commercial manufacturers of ELISA kits to eliminate non-HTLV-III antigens from their test systems to decrease the proportionately large number of false positive tests results that occur currently. Blood Center of Southeastern Wisconsin, Inc, Milwaukee, Wisconsin, USA
JAY B. HUNTER JAY E. MENITOVE
OVERINVESTIGATION
SIR,-The patient Dr Jenkins describes (May 25, p 1213) saw several specialists. Damage to the spinal accessory nerve was identified by one, deltoid atrophy by another, decreased sensation by a third, a positive Adson’s manoeuvre by a fourth, and thoracic outlet syndrome was diagnosed by a fifth. Even the electromyogram was felt to be abnormal. Ultimately, the man was shown by the insurance company involved to be malingering. This is a strong comment on the limitations of our clinical method and on our need to make a diagnosis. When five of twelve doctors identify abnormalities that are not there, we have to reflect on how we might improve our skills. Every test, both in physical examination and in diagnostic investigation, has inherent limitations which depend upon the test’s
and widespread hyperostosis as a complication oflong-term therapy has been reported. In contrast, in patients receiving etretinate (’Tigason’), there has hitherto been only one report3 of a disorder of ossification, and this was localised to the forearms. A 38-year-old man with a recessive form of ichthyosis (congenital non-bullous ichthyosiform erythroderma) started taking etretinate 50 mg/daily (0 -6 mg/kg) in March, 1980. His skin improved. The daily dose was increased to 75 mg and then, after 5 months, was reduced to a maintenance level of 50 mg. In November, 1984, the dose was reduced to 25 mg and he took this dose until April, 1985. In June, 1984, he noted vague musculoskeletal pains when lifting heavy objects. He practises the martial arts and noted increasing stiffness and discomfort, mainly in the thoracic spine and ribs. In April, 1985, there was limitation of movement of the thoracic spine and tenderness over the costal cartilages. X-rays suggested diffuse idiopathic skeletal hyerostosis (figure). There was ossification at the insertion of muscles around the pelvis and upper femora, ossification of the iliolumbar ligaments, and bridging of the anterior borders of the thoracic vertebral bodies. Isotope bone scans demonstrated focal areas of increased activity around the ossified iliolumbar ligaments, at the inferior borders of both sacroiliac joints, and along the anterior aspect of the cervicothoracic junction, confirming a predominantly axial hyperostosis. Serum calcium, phosphate, alkaline phosphatase, renal function, liver function, and fasting lipids were normal. Between October, 1957, and November, 1964, the patient had been treated with oral vitamin A (200 000-300 000 units daily). In November, 1958, signs of vitamin A toxicity developed. He had pains in the wrists and knees, bone tenderness, and hepatomegaly, but a liver biopsy showed no irreversible changes. Symptoms resolved when vitamin A was stopped temporarily and he was able to continue treatment for another six years. Topical vitamin A acid and topical retinoic acid were also used for prolonged periods.
SiR.—Dr Kuhnl and colleagues (May 25, p 1222) provide evidence that HLA-DR4 antibodies may give positive results in enzyme-linked immunosorbent assays (ELISA) used to detect antibodies to human T-cell lymphotropic virus type III (HTLV-III). 10 of 27 (37%) DR4 alloantisera were positive in the ELISA. The 10 monoclonal antisera were ELISA negative; however, this is expected since the second antibody, anti-human IgG, would not react with the mouse monoclonals even if they bound to the bead. The data suggest that HLA-DR4 antigen is present on the test beads used in the ELISA and, therefore, on H9, the cell line from which viral antigen is isolated for use in commercially available test kits. Professor Weiss and colleagues (July 20, p 156) typed H9 and confirmed the presence ofDR4 as well as HLA Al, Bw62, Bw6, Cw3, and DQw3. To examine whether the ELISA positives are caused by DR4 antibodies, we tested HLA antisera, procured locally from multiparous women, with Abbott ELISA kits. Class I antisera directed against HLA A, B, C found on H9 and DR antisera specific for non-H9 associated specificities were ELISA negative. 1 of 5 antiDR4 and 3/4 anti-DQw3 sera were reproducibly ELISA positive. All sera tested were negative for HTLV-III antibodies by western blot. To extend the evidence that not only DR4 but also DQw3 antibodies give positive results in HTLV-111 ELISA tests we did HLA antibody analysis on sera from 20 ELISA repeatedly reactive blood donors. 6 of the donors were also HTLV-111 antibody positive by western blot. 4 of the 20 sera have DQw3 or DR4 specificity and an additional 5 reacted with some DR4 and DQw3 cells: for HTL h111 antibody positive/western blot negative (n== 14) ELISA positive/western blot positive (n=6)
Anll-HLA
Donors pOSlln’e
ELISA
speciflcltzes detected DQw3, 1 DR4, 1 DQwl, non-specific,* 9 negative DQw3, 1 A9+,* 3 non-specific,* 2 1
1
*
sensitivity and specificity and upon the likelihood of the disease being present. Even for a very sensitive and specific test, a single positive finding, such as deltoid atrophy or a positive Adson’s manoeuvre, is more likely to represent a false positive than true disease, if the clinical picture suggests that the disease is unlikely. Clinicians should also recognise that their judgment may be affected by the priority they place on making a diagnosis. A physician who thinks that making a diagnosis is all-important may zealously pursue a diagnosis "because it is there"’ or may follow the maxim "when in doubt make a diagnosis".The attitude that it is much worse to call a sick person well, than to call a well person sick is deeply engrained in the medical profession and is supported by legal sanction (especially in the USA).3This attitude underlies the "minimax" decision strategy or "better safe than sorry" approach, through which the doctor aims to minimise the chances of maximum possible loss or the worst outcome by directing investigation towards the most serious, though improbable, diagnosis.4All these biases in decision making may result in overdiagnosis or
misdiagnosis. As Jenkins implies, his patient and the community would have been better served if the physicians involved had recognised the limitations of their tests and curbed their desires to make a diagnosis. As family physicians we would have liked to know how the patient reacted to the revelation of his fitness and what the final outcome was.
Department of Family Medicine, University of Western Ontario, London, Ontario, Canada N6A 5C I 1 Editorial.
Iatrogenesis Just what the
MARTIN J. BASS ROGER P. STRASSER doctor
ordered. J Community
Health 1980, 5:
149-57. 2 Wulff HR Rational diagnosis and treatment Oxford Blackwell, 1976: 114 3 Reiser SJ Medicine and the reign of technology Cambridge Cambridge University Press, 1978, 192 4 Bursztajn H, Feinbloom RI, Hamm RM, Brodsky A Medical choices, medical chances New York: Merloyd Lawrence, 1981 189-90
1 negative
*Reactivity not sufficient to assign specificity; however, sera preferentially reacted with DQw3 positive B cells These data indicate that reactivity in HTLV-III ELISA assays can
DIFFUSE HYPEROSTOSIS ASSOCIATED WITH ETRETINATE
be due to DR4 and also DQw3 antibodies. However, we agree with Weiss et al that HLA antibody evaluation does not distinguish false positive ELISA results since one of our 6 western blot positive donors also has anti-DQw3 and 3 have non-specific class II HLA
SIR,-The retinoids are now the drugs of choice for the management of severe disorders of keratin is at ion such as ichthyosis. Isotretinoin (’Accutane’) has been used widely in the United States,
DR4 and
antibody. Western blot results are currently used for verification of HTLVIII antibodies detected by ELISA. The validity of this approach is supported by our finding that none of the HLA typing sera were positive by western blot and that 89% of western blot positive donors reported in the US by the Council of Community Blood Centers are males. Nevertheless, there is an urgent need to confirm this assumption by viral cultures or HTLV-III antigen specific testing. In addition, we strongly urge commercial manufacturers of ELISA kits to eliminate non-HTLV-III antigens from their test systems to decrease the proportionately large number of false positive tests results that occur currently. Blood Center of Southeastern Wisconsin, Inc, Milwaukee, Wisconsin, USA
JAY B. HUNTER JAY E. MENITOVE
OVERINVESTIGATION
SIR,-The patient Dr Jenkins describes (May 25, p 1213) saw several specialists. Damage to the spinal accessory nerve was identified by one, deltoid atrophy by another, decreased sensation by a third, a positive Adson’s manoeuvre by a fourth, and thoracic outlet syndrome was diagnosed by a fifth. Even the electromyogram was felt to be abnormal. Ultimately, the man was shown by the insurance company involved to be malingering. This is a strong comment on the limitations of our clinical method and on our need to make a diagnosis. When five of twelve doctors identify abnormalities that are not there, we have to reflect on how we might improve our skills. Every test, both in physical examination and in diagnostic investigation, has inherent limitations which depend upon the test’s
and widespread hyperostosis as a complication oflong-term therapy has been reported. In contrast, in patients receiving etretinate (’Tigason’), there has hitherto been only one report3 of a disorder of ossification, and this was localised to the forearms. A 38-year-old man with a recessive form of ichthyosis (congenital non-bullous ichthyosiform erythroderma) started taking etretinate 50 mg/daily (0 -6 mg/kg) in March, 1980. His skin improved. The daily dose was increased to 75 mg and then, after 5 months, was reduced to a maintenance level of 50 mg. In November, 1984, the dose was reduced to 25 mg and he took this dose until April, 1985. In June, 1984, he noted vague musculoskeletal pains when lifting heavy objects. He practises the martial arts and noted increasing stiffness and discomfort, mainly in the thoracic spine and ribs. In April, 1985, there was limitation of movement of the thoracic spine and tenderness over the costal cartilages. X-rays suggested diffuse idiopathic skeletal hyerostosis (figure). There was ossification at the insertion of muscles around the pelvis and upper femora, ossification of the iliolumbar ligaments, and bridging of the anterior borders of the thoracic vertebral bodies. Isotope bone scans demonstrated focal areas of increased activity around the ossified iliolumbar ligaments, at the inferior borders of both sacroiliac joints, and along the anterior aspect of the cervicothoracic junction, confirming a predominantly axial hyperostosis. Serum calcium, phosphate, alkaline phosphatase, renal function, liver function, and fasting lipids were normal. Between October, 1957, and November, 1964, the patient had been treated with oral vitamin A (200 000-300 000 units daily). In November, 1958, signs of vitamin A toxicity developed. He had pains in the wrists and knees, bone tenderness, and hepatomegaly, but a liver biopsy showed no irreversible changes. Symptoms resolved when vitamin A was stopped temporarily and he was able to continue treatment for another six years. Topical vitamin A acid and topical retinoic acid were also used for prolonged periods.