파종성결핵환자에서 interferon-γ 수용체의부분결핍에관한연구 성균관대학교의과대학내과학교실, 삼성서울병원호흡기내과황정혜, 고원중, 이신혜, 김은주, 강은해, 서지영, 정만표, 김호중, 권오정 Partial Interferon-γ Receptor Deficiency in Patients with Disseminated Tuberculosis Jung Hye Hwang, M.D., Won-Jung Koh, M.D., Shin Hye Lee, B.S., Eun Joo Kim, Ph.D., Eun Hae Kang, M.D., Gee Young Suh, M.D. Man Pyo Chung, M.D., Hojoong Kim, M.D., O Jung Kwon, M.D. Division of Pulmonary and Critical Care Medicine, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea Background : Interferon-gamma (IFN-γ) is essential in the immune response to mycobacterial infections, and a complete or partial deficiency in the IFN-γ receptor 1 (IFNγR1) or the IFN-γ receptor 2 (IFNγR2) have been reported to confer susceptibility to a disseminated infection with nontuberculous mycobacteria. However, similar mutations in the IFN-γ receptor have not been specifically examined in the patients with clinical tuberculosis. Methods : This study searched for mutations in the IFN-γ receptor gene that resulted in a partial IFN-γ receptor deficiency in six patients with disseminated tuberculosis. The previously identified IFNγR1 and IFNγR2 coding regions were sequenced after amplification. Results : There was no partial IFNγR1 deficiency including a homozygous recessive missense mutation causing an amino-acid substitution in the extracellular domain of the receptor (I87T) and a hotspot for small deletions (818delT, 818del4, 818insA) found in any of the patients. In addition, a partial IFNγR2 deficiency of the homozygous missense mutation (R114C) was not found in any of the patients. Conclusion : Genetic defects causing a partial IFN-γ receptor deficiency were not identified in our patients with disseminated tuberculosis. (Tuberc Respir Dis 2005; 58:11-17) Key words : Tuberculosis, Genetic predisposition to disease, Interferon receptors, Point mutation 서 결핵은결핵균 (Mycobacterium tuberculosis) 에의한감염성질환이지만결핵균에감염된사람들중약 10% 에서만임상적인질병으로서결핵이발병한다. 이러한사실은개체에따라결핵균에대한감수성이차이가있고, 이러한결핵발병의감수성에영향을미치는유전적인요인이있음을시사한다 1-3. 우리몸에결핵균이감염된후면역반응을담당하 * 이연구는삼성생명과학연구소연구비 (C-A4-203-1) 의보조로이루어졌음. Address for correspondence : Won-Jung Koh, M.D. Division of Pulmonary and Critical Care Medicine, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, 50 Irwon-dong, Gangnam-gu, Seoul 135-710, Republic of Korea Phone : 822-3410-3429 Fax : 822-3410-3849 E-mail : wjkoh@smc.samsung.co.kr Received : Aug. 30. 2004 Accepted : Dec. 21. 2004 론 는가장중요한세포는폐포대식세포 (macrophage) 이며, 대식세포를활성화하여결핵균의살균력을증가시키는데에는 interferon-gamma (IFN-γ) 가중요한역할을한다 4,5. 최근에는결핵균과구조적, 생화학적유사성을가지고있으나병원성이약한비결핵항산균 (nontuberculous mycobacteria, NTM) 에의한파종성 (disseminated) 감염증이발생하거나 BCG (Bacille Calmette-Guerin) 접종후파종성감염증이발생한환자에서 IFN-γ 수용체유전자의결핍이밝혀졌다 6-8. 이러한소견은 IFN-γ 를통한세포내신호전달경로의유전적결함이결핵발병의숙주감수성과관련이있음을시사하는것이다. 하지만파종성 NTM 감염증이나파종성 BCG 감염증환자가아닌결핵환자에서이러한유전적이상이발견된경우는매우드물다 9. IFN-γ 수용체 (IFNγR) 는배위자결합사슬 (ligand binding chain) 인 IFNγR1과신호전달사슬 (signal transduction chain) 인 IFNγR2, 이렇게 2개의사슬로구성되어있으며, 이를부호화 (encoding) 하는유전자 11
JH Hwang, et al.: Partial interferon-γ receptor deficiency in eisseminated tuberculosis 는 IFNγR1과 IFNγR2이다 10-12. IFNγR1 유전자의돌연변이는수용체의완전결핍 (complete IFNγR1 deficiency) 과부분결핍 (partial IFNγR1 deficiency) 을초래할수있으며, 마찬가지로 IFNγR2 유전자의돌연변이도수용체의완전결핍 (complete IFNγR2 deficiency) 과부분결핍 (partial IFNγR2 deficiency) 을초래할수있다 10-12. 발생하는질병의조직학적, 임상적표현형 (phenotype) 의중증도는이러한 IFN-γ 수용체의유전적이상에따라서달라지게된다 10-12. IFNγR1의완전결핍과 IFNγR2의완전결핍은어린소아연령에서전신적인파종성 NTM 감염증을일으키고조직학적으로육아종 (granuloma) 의형성을관찰할수없으며치료에대한반응이불량하여대부분사망한다. 이에반해서 IFNγR1의부분결핍과 IFNγ R2의부분결핍은다양한연령에서좀더경증의 NTM 감염증을일으키고조직학적으로육아종의형성을관찰할수있으며, 치료에대한반응이상대적으로좋다 10-12. 이러한사실은성인에서발생하는결핵이 IFN-γ 수용체의유전적이상과관련이되어있다면, 이는완전결핍이아닌부분결핍과연관되어있을가능성을시사한다. 하지만결핵환자에서 IFN-γ 수용체의부분결핍이밝혀진경우는현재까지 3세소아환자에서의증례보고밖에없는실정이다 9. 본연구는임상적결핵환자중숙주면역반응에결함이있을가능성이높을것으로예상되는파종성결핵환자를대상으로 IFN-γ 수용체의부분결핍을초래하는유전적이상이있는지를알아보고자하였다. 대상및방법 1. 연구대상 2003년 4월부터 2004년 3월까지삼성서울병원호흡기내과에입원한환자중 2개이상의장기를침범한파종성결핵환자 6명을대상으로하였다 (Table 1). 대상환자의중앙연령은 29세 ( 범위 19-36세 ) 였고남자가 2명여자가 4명이었다. 악성종양을가진환자나기저질환의치료를위해면역억제제를사용하는등 세포매개면역 (cell-mediated immunity) 에장애를초래할만한조건을가진환자는없었다. 본연구는삼성서울병원임상시험심사위원회 (Institutional Review Board) 의허가를받았으며, 대상환자에게서면화된동의서를받은후연구를진행하였다. 2. 연구방법환자로부터말초혈액 5 cc를채취하여 G-DEXTM Genomic DNA Extraction kits (intron Biotechnology, Sungnam, South Korea) 를이용하여 genomic DNA 를분리하였다. (1) IFN-γ 수용체유전자 1 (IFNγR1) 돌연변이의확인 IFN-γ 수용체유전자 1의부분결핍여부를확인하기위해기존의연구에서보고된부위를목표로하여중합효소연쇄반응 (polymerase chain reaction, PCR) 을시행하고염기순서를확인하였다. 현재까지유전적결함이밝혀진부위에대해각각 primer을제작하였고 primer 염기순서는다음과같다 9,13,14. Exon 3: 5'-CTG TGA ATA AAA AGC AAA GC-3' (sense) 5'-AAA GCA AAC ATA CAG AAG AC-3' (antisense) Exon 6: 5'-TGT AAC TTG TGA TTT CTG CC-3' (sense) 5'-GTA GAC TGA CTG ATT GAT G-3' (antisense) PCR 반응액의조성은 200 μm deoxynucleotide triphosphates, genomic DNA 200 ng, 2 mm MgCl 2, primer 10 pmole, Taq DNA polymerase 1 units/μl (Promega, Madison, WI, USA) 를넣고살균된증류수로최종부피가 50 μl가되도록하였다. 위의반응액을 94 에서 10분간반응시키고, 94 에서 40초, 5 6 에서 40초, 72 에서 40초씩 Perkin-Elmer model 9600 thermal cycler (Perkin Elmer, Branchburg, NJ, USA) 로 35 cycle을수행한후 72 에서 10분간반응 12
Tuberculosis and Respiratory Diseases Vol. 58. No. 1, Jan, 2005 Table 1. Clinical characteristics of the patients Age/Sex Disease Diagnosis of tuberculosis Radiologic findings 21/F TB peritonitis, TB pleurisy 29/F TB meningitis Cerebral TB Miliary TB Ascites: lymphocyte-dominant exudates, ADA 88 IU/L Pleural effusion: lymphocyte dominant exudates, ADA 100 IU/L CSF: WBC 50/μl (lymphocyte 84%), glucose 42 mg/dl BAL fluid: TB-PCR+ Abdomen CT: complicated ascites with omental cake formation, bilateral pleural effusion Brain MRI: multiple enhancing nodules su ggestive small abscess Chest CT: multiple centrilobular nodules and tubular branching structure in both lungs Treatment outcome 29/F Miliary TB Hepatosplenic TB TB lymphadenitis (neck, mediastinum) Neck LN aspiration: AFB smear 2+, TB PCR+ Sputum: TB-PCR+ Chest CT: multiple small nodules in both lungs, multiple necrotic lesions in neck and mediastinal lymph nodes, multiple small low attenuated nodules in spleen and liver 36/F Pulmonary TB Renal TB Sputum: AFB smear 4+, culture 3+ Chest CT; centrilobular nodules and branch } Urine: AFB smear 1+, culture ± ing structure in both lungs M. tuberculosis isolated (all sensitive) Abdomen CT: hydronephrosis in left kidney, Left nephrectomy: chronic granulomatous thickened and enhanced wall of renal pelvis inflammation and ureter 31/M Intestinal TB Pulmonary TB Colonoscopic biopsy: chronic active infla Abdomen CT: multiple segmental wall th mmation with cryptitis and microgranulomas ickening in small intestine, cecum, ascending Colonoscopic biopsy: M. tuberculosis isolated and transverse colon, small amount of ascites (all sensitive) Chest CT: multiple centrilobular nodules in both lungs 19/M TB peritonitis, TB pleurisy, TB lymphadenitis (mediastinum) Ascites: lymphocyte-dominant exudates, ADA Abdomen CT: complicated ascites with 163 IU/L omental lesion Peritoneal biopsy: chronic granulomatous Chest CT: central necrotic mass with rim inflammation with caseation necrosis enhancement in right paratracheal area, bilateral pleural effusion Definition of abbreviation: TB = tuberculosis; ADA = adenosine deaminase; CT = computed tomography; CSF = cerebrospinal fluid; WBC = white blood cells; BAL = bronchoalveolar lavage; PCR = polymerase chain reaction; MRI = magnetic resonance imaging; AFB = acid fast bacilli; LN = lymph node. 시켰다. 염기순서분석 (sequencing) 을통해 exon 3의 nucleotide 260번위치에서발생한염기치환 (T C, I87T) 과 exon 6의 818 번위치에서 T nucleotide (818delT) 의결손과 4 nucleotide 의결손 (818del4), A nucleotide 의삽입 (818insA) 으로인한유전자돌연변이를분석하였다. (2) IFN-γ 수용체유전자 2 (IFNγR2) 돌연변이의확인위와마찬가지로 IFN-γ 수용체유전자 2의부분결핍여부를확인하기위해기존의연구에서보고된부위를목표로하여 PCR를시행하고염기서열을확인하였다. PCR primer는현재까지유전적결함이밝혀진부위에대해각각 primer을제작하였고 primer 염기서열은다음과같다 15. Exon 3: 5 -ATTCTGTGAATTGAAATGGT-3 (sense) 5 -TGAAGAAAACCTGGAAAGTA-3 (antisense) 염기순서분석을시행한후 exon 3부위의 340번위치에서발생한염기치환 (C T, R114C) 의유무를분석하였다. 결 과 1. IFN-γ 수용체유전자 1 (IFNγR1) 의돌연변이 6명의환자를대상으로 IFN-γR1의염기순서를분석한결과파종성 NTM 감염증또는파종성 BCG 감염증환자에서발견되었던 exon 3의 I87T, exon 6의 13
JH Hwang, et al.: Partial interferon-γ receptor deficiency in eisseminated tuberculosis 818delT, 818del4, 818insA 돌연변이는확인할수없었다 (Fig. 1. A. B.). 2. IFN-γ 수용체유전자 2 (IFNγR2) 의돌연변이 6명의환자모두에서 NTM과 BCG 감염증이발생한환자를대상으로밝혀진 exon 3의 R114C 돌연변이는관찰할수없었다 (Fig. 1. C.). A B C Figure 1. Mutation analysis of the interferon-γ receptor gene. A. The region surrounding position 260 of the IFNγR1 coding region in exon 3. B. The region surrounding position 818 of the IFNγR1 coding region in exon 6. C. The region surrounding position 340 of the IFNγR2 coding region in exon 6. 고찰본연구는결핵환자중숙주면역반응에결함이있을가능성이높은파종성결핵환자를대상으로 IFNγ 수용체의부분결핍을초래하는유전자이상이있는지를알아보고자하였다. 하지만기존에파종성 NTM 감염증과 BCG 감염증에서보고된유전자돌연변이를찾을수없었다. 결핵균에대한숙주의면역반응은세포성면역반응이주를이루는데 16,17, 대식세포와 T-림프구가중요한역할을한다. 대식세포는감염된결핵균을탐식하고 nitric oxide나 reactive oxygen intermediate의생산을증가시켜 18 탐식한결핵균을죽일수있다. 이때대식세포를활성화시켜결핵균의살상능력을높이는데는 IFN-γ 가중요하다고알려져있다. IFN-γ responsive element가없는쥐는결핵균에감염되었을때방어능력이없어쉽게사망한다는보고가있고 19, IFN-γ 수용체유전자를제거한쥐모델도조직괴사를심하게일으키며조기에사망하는결과를보여주었다 4,20. 1996년 Newport 등 6 은파종성 NTM 감염증환자들을대상으로연구한결과말초혈액단핵구의항원에대한증식반응감소와 IFN-γ, tumor necrosis factor-α 의분비능이저하되어있는것을확인하였고, 이것이 IFNγR1 유전자의돌연변이때문이라는것을밝혔다. IFNγR1 유전자의 395번핵산위치에서 C가 A로바뀌는점돌연변이 (point mutation) 가생겨 IFN-γ 가결합해야할수용체가생성되지않아 IFN-γ 가기능을할수없게된것이다. 이후현재까지이러한 IFNγR1의완전결핍은 13가족내 21명의환자가보고되었고 11, 모두어린소아에서발생한매우심한파종성 NTM 또는파종성 BCG 감염증증례로, 조직학적으로육아종의형성을관찰할수없었다. 수용체의완전결핍이발생하였기때문에 IFN-γ 를투여하더라도치료에는효과가없어, 골수이식만이현재유일한치료법으로인정되고있다 10-12. 이와달리 IFNγR1의부분결핍이발생한경우는임상적으로좀더경증의 NTM 감염증을초래하고, 조직학적으로육아종의형성을관찰할수있다. IFN 14
Tuberculosis and Respiratory Diseases Vol. 58. No. 1, Jan, 2005 γr1의부분결핍은 BGC 접종이후파종성 BCG 감염증이발생한소아와 BCG 접종을받지않고폐결핵이발생한형제에서 1997년처음으로보고되었다 9. 이들환자에서는과오돌연변이 (missense mutation) 로인해수용체일부분의아미노산이치환 (I87T) 된것이발견되었다. 이러한유전자돌연변이를통해 IFN-γ 가수용체에결합하는친화력이감소되기는하지만, 완전히소실되지는않는것으로보고되고있다. 따라서이환자들은 IFN-γ 치료에반응을보이게된다. 이후여러부위의 IFNγR1 유전자의돌연변이를동반한부분 IFNγR1 결핍증의증례가보고되었다 13,14. IFNγR2의돌연변이는 1998년파종성 M. avium과 M. fortuitum 감염증이발생한소아환자에서밝혀졌다. 이환자는 IFNγR2 유전자의이상 (homozygous dinucleotide deletion at nucleotides 278 and 279) 에의해수용체의세포외부분에 premature stop codon 이생성되어 IFN-γ 가전혀반응을하지못한다 8. 이러한 IFNγR2의완전결핍은 IFNγR1 완전결핍과마찬가지로소아에서심한파종성 NTM 감염증을초래하며, 치료는골수이식이유일하다고알려져있다 10-12. IFNγR2의부분결핍은 2000년 Doffinger 등 15 에의하여과거파종성 BCG 감염증과 NTM 감염증을앓은 20세환자에서과오돌연변이 (R114C) 에의해서수용체의세포외부위의아미노산치환이발생한것이처음으로보고되었다. 이환자의경우에 IFN-γ 투여후의세포반응은감소되어있었으나완전히소실된것은아니었다. 이와같이 IFNγR1의완전결핍과 IFNγR2의완전결핍은어린소아연령에서전신적인파종성 NTM 감염증또는파종성 BCG 감염증을일으키고조직학적으로육아종의형성을관찰할수없으며예후가매우불량하다 10-12. 이에반해서 IFNγR1의부분결핍과 IFNγR2의부분결핍은다양한연령에서좀더경증의 NTM 감염증을일으키고조직학적으로육아종의형성을관찰할수있으며, 보통약물치료에반응을한다 10-12. 이러한 IFN-γ 수용체의돌연변이의특성을볼때성인에서발생하는결핵환자에서 IFN-γ 수용체유전자이상에의한면역반응이상이있다면이것은 IFN-γ 수용체의완전결핍보다는부분결핍이관여할가능성이높다고추정할수있을것이다. Park 등 21 은속립성결핵또는파종성결핵환자 18명을대상으로 IFNγR1의완전결핍유무를살펴보았으나, 이러한유전자이상이발견된환자는없었다. 한편 Lee 등 22 은난치성결핵환자 9명중 33세여자환자 1명에서말초혈액림프구표면의 IFN-γ 수용체발현이감소되어있고, IFN-γ 로전처치후 lipopolysaccharide로말초혈액단핵구를자극하였을때, tumor necrosis factorα의증가가발생하지않았다고보고하여, 이환자가 IFN-γ 수용체의부분결핍이있을가능성을보여주었으나, 유전자돌연변이을직접밝히지는못하였다. 본연구는결핵환자중숙주의면역반응에결함이있을가능성이상대적으로높은환자즉, 2개이상의장기를침범한파종성결핵환자를대상으로하여 IFN-γ 수용체의부분결핍유무를살펴보았다. 하지만 IFNγR1 유전자 exon 3 부위의 I87T와 exon 6 부위의 818delT, 818del4, 818insA 그리고 IFNγR2 유전자 exon 3 부위의 R114C 돌연변이등기존에보고된유전자돌연변이를확인하지는못하였다. 결핵균은 BCG나 NTM과구조적, 생화학적유사성을가지고있기는하지만, 결핵균은좀더독성이강한균이기때문에개체면역에있어 IFN-γ 수용체의결핍과같은유전자결손보다는좀더미미한변화가개체들사이의감염과발병에대한감수성의차이를결정할수도있을것이다. 결론적으로본연구에서는파종성 NTM 감염증과 BCG 감염증에서숙주면역반응과관련이있다고알려진 IFN-γ 수용체의부분결핍을연구대상이었던소수의결핵환자에서발견하지는못하였으며, 이환자들의결핵에대한숙주감수성을 IFN-γ 수용체의부분결핍을초래하는유전자이상으로설명할수는없었다. 요약연구배경 : 결핵의발병에유전적인소인이존재하며숙주면역반응에 IFN-γ 가중요한역할을한다고알려져있 15
JH Hwang, et al.: Partial interferon-γ receptor deficiency in eisseminated tuberculosis 다. 파종성 NTM 또는 BCG 감염증환자에서 IFN-γ 수용체유전자돌연변이가밝혀져있는데, 결핵환자에서 IFN-γ 수용체의부분결핍유무는잘알려져있지않았다. 방법 : 2개이상의장기를침범한파종성결핵환자 6명을대상으로염기순서분석을통해 IFN-γ 수용체 1과 IFN-γ 수용체 2의부분결핍을초래하는유전자이상이있는지를살펴보았다. 결과 : IFN-γR1의부분결핍을초래하는 I87T와 818delT 818del4, 818insA 그리고 IFN-γR2의부분결핍을초래하는 R114C 돌연변이등기존에보고된유전자이상은발견되지않았다. 결론 : 본연구의대상인 6명의파종성결핵환자에서 IFN-γ 수용체의부분결핍을초래하는유전자이상은발견되지않았다. 참고문헌 1. Murray CJ, Styblo K, Rouillon A. Tuberculosis in developing countries: burden, intervention and cost. Bull Int Union Tuberc Lung Dis 1990;65:6-24. 2. Bellamy R. Genetics and pulmonary medicine: 3. genetic susceptibility to tuberculosis in human po pulations. Thorax 1998;53:588-93. 3. Bellamy R. Susceptibility to mycobacterial infections: the importance of host genetics. Genes Immun 2003; 4:4-11. 4. Flynn JL, Chan J, Triebold KJ, Dalton DK, Stewart TA, Bloom BR. An essential role for interferon γ in resistance to Mycobacterium tuberculosis infection. J Exp Med 1993;178:2249-54. 5. Schluger NW, Rom WN. The host immune response to tuberculosis. Am J Respir Crit Care Med 1998; 157:679-91. 6. Newport MJ, Huxley CM, Huston S, Hawrylowicz CM, Oostra BA, Williamson R, et al. A mutation in the interferon-γ-receptor gene and susceptibility to mycobacterial infection. N Engl J Med 1996;335: 1941-9. 7. Jouanguy E, Altare F, Lamhamedi S, Revy P, Emile JF, Newport M, et al. Interferon-γ-receptor de ficiency in an infant with fatal bacille Calmette- Guerin infection. N Engl J Med 1996;335:1956-61. 8. Dorman SE, Holland SM. Mutation in the signaltransducing chain of the interferon-γ receptor and susceptibility to mycobacterial infection. J Clin Invest 1998;101:2364-9. 9. Jouanguy E, Lamhamedi-Cherradi S, Altare F, Fondaneche MC, Tuerlinckx D, Blanche S, et al. Partial interferon-γ receptor 1 deficiency in a child with tuberculoid bacillus Calmette-Guerin infection and a sibling with clinical tuberculosis. J Clin Invest 1997;100:2658-64. 10. Holland SM. Immune deficiency presenting as my cobacterial infection. Clin Rev Allergy Immunol 2001; 20:121-37. 11. Doffinger R, Dupuis S, Picard C, Fieschi C, Fein berg J, Barcenas-Morales G, et al. Inherited disorders of IL-12- and IFN-γ-mediated immunity: a molecular genetics update. Mol Immunol 2002;38:903-9. 12. Guide SV, Holland SM. Host susceptibility factors in mycobacterial infection: genetics and body mor photype. Infect Dis Clin North Am 2002;16:163-86. 13. Dorman SE, Uzel G, Roesler J, Bradley JS, Bastian J, Billman G, et al. Viral infections in interferon-γ receptor deficiency. J Pediatr 1999;135:640-3. 14. Villella A, Picard C, Jouanguy E, Dupuis S, Popko S, Abughali N, et al. Recurrent Mycobacterium avium osteomyelitis associated with a novel dominant in terferon gamma receptor mutation. Pediatrics 2001; 107:E47. 15. Doffinger R, Jouanguy E, Dupuis S, Fondaneche MC, Stephan JL, Emile JF, et al. Partial interferon-γ receptor signaling chain deficiency in a patient with bacille Calmette-Guerin and Mycobacterium absce ssus infection. J Infect Dis 2000;181:379-84. 16. North RJ. Importance of thymus-derived lymphocytes in cell-mediated immunity to infection. Cell Immunol 1973;7:166-76. 17. Orme IM, Collins FM. Protection against Mycobac terium tuberculosis infection by adoptive immuno therapy: requirement for T cell-deficient recipients. J Exp Med 1983;158:74-83. 18. Orme IM, Roberts AD, Griffin JP, Abrams JS. Cytokine secretion by CD4 T lymphocytes acquired in response to Mycobacterium tuberculosis infection. J Immunol 1993;151:518-25. 19. Dalton DK, Pitts-Meek S, Keshav S, Figari IS, Bradley A, Stewart TA. Multiple defects of immune cell function in mice with disrupted interferon-γ genes. Science 1993;259:1739-42. 20. Kamijo R, Le J, Shapiro D, Havell EA, Huang S, Aguet M, et al. Mice that lack the interferon-γ re ceptor have profoundly altered responses to infection 16
Tuberculosis and Respiratory Diseases Vol. 58. No. 1, Jan, 2005 with Bacillus Calmette-Guerin and subsequent ch allenge with lipopolysaccharide. J Exp Med 1993; 178:1435-40. 21. Park GY, Hwang YJ, Lim YH, An CH, Park JW, Jeong SH. The functional and genetic defects of IFNγ receptor in the patients with tuberculosis. Tuberc Respir Dis 2002;52:497-505. 22. Lee JC, Yoo CG, Lee CT, Kim YW, Han SK, Shim YS. The priming effect of IFN-γ and numbers of IFN-γ receptors in patients with chronic refractory tuberculosis. Tuberc Respir Dis 1999;47:304-10. 17