lymphoid ceUs in aU nine cases examined rather than in B ceUs as previously believed in infectious mononucleosis. Considering the young affected age of the ...
American journal of Pathology, Vol. 144, No. 6, June 1994 Copyright © American Society for Investigative Pathology
Epstein-Barr Virus (EBV) Infects T Lymphocytes in Childhood EBV-Associated Hemophagocytic Syndrome in Taiwan
Ih-Jen Su, Rong-Long Chen, Dong-Tsammn Lin, Kai-Sin Lin, and Chun-Chun Chen From the Departments of Pathology and Pediatrics, National Taiwan University Hospital and College of Medicine, Taipei, Taiwan
We have reported the prevalence of a fulminant
hemophagocytic syndrome (HS) in previously healthy young children in Taiwan, most of which probably represent a lethalform of primary or active Epstein-Barr virus (EBV) infection. Tofurther confirm their EBV association, in situ EBV hybridization (ISH) was performed on tissue biopsies from 15 pediatric HS patients (median age, 3 years and 4 months) using digoxigeninlabeled RNA probes EBERI. Double labeling immunostaining and ISH was then performed to deJine the immunophenotype of the lymphoid ceUs containing the EBV transcripts. Among the 13 patients who had serological evidence of acute or active EBV infection, 9 had demonstrable EBERI transcripts in bone marrow, liver, and/or skin biopsies. EBER1-specific signal was not detectable in the two specimens from EBV-seronegative patients. The distribution of EBV-containing cells could be extensive or scattered. To our surprise, the EBERI transcripts existed exclusively in T lymphoid ceUs in aU nine cases examined rather than in B ceUs as previously believed in infectious mononucleosis. Considering the young affected age of the HS patients and the serological response to EBV, we suggest that EBV can infect T ceUs in primary EBV infection and the proliferation of these EBV-infected T cells may be responsible for the ominous outcome in childhood HS patients in Taiwan. (Am J Pathol 1994, 144:1219-1225)
Hemophagocytic syndrome (HS) is a systemic lymphohistiocytic proliferative disorder associated with infection or malignancies. 1-6 The majority of HS cases
are found to be associated with viruses, particularly the Epstein-Barr virus (EBV), designated virusassociated hemophagocytic syndrome (VAHS).1 3-8 The disease is characterized by a constellation of clinical and laboratory features such as high fever, skin rash, pulmonary infiltrate, jaundice, hepatosplenomegaly, cytopenia, and coagulopathy. The demonstration of lymphohistiocytic infiltration with phagocytosis of erythrocytes and nucleated blood cells in the bone marrow and lymphoid organs establishes the diagnosis of HS in such patients. We have reported the prevalence of a fulminant form of EBV-associated HS (EBV-AHS) affecting previously healthy young children or toddlers in Taiwan.7'8 Some of the cases have been previously interpreted as histiocytic medullary reticulosis or malignant histiocytosis and were treated as such with universally ominous outcome.7-9 We speculate that these pediatric EBV-AHS cases probably represent a lethal form of primary EBV infection based on the strong correlation of the affected age of our EBV-AHS patients with the age distribution of EBV seroconversion in the general populations in Taiwan.7'10 Because the majority of EBV-AHS cases in western countries occur in immunocompromised hosts,'1 511 the prevalence of EBV-AHS in previously healthy children in Taiwan constitutes an important pathobiological disease entity remained to be investigated. In this study, by double labeling immunohistochemistry and in situ hybridization, we further confirm that the majority of childhood HS cases in Taiwan are associated with EBV. To our surprise, the EBV infects exclusively T lymphoid cells in all EBV-AHS cases examined rather than in the initially believed B cells, providing important information to investigate the pathogenesis of childhood EBV-AHS. This work was supported by research grants from the National Science Council (NSC 83-0412-B-002-298) and Academic Sinica, Taipei, Taiwan (I-JS). Accepted for publication January 25, 1994. Address reprint requests to Dr. Ih-Jen Su, Department of Pathology, National Taiwan University Hospital and College of Medicine, Chung-San South Road, Taipei, Taiwan.
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Materials and Methods Patients and Brief Clinical Informations A total of 17 childhood HS patients were encountered in the pediatric ward of National Taiwan University Hospital during the periods of 1990 to 1993. Among them 15 patients had available tissue materials for additional examinations and were included in this study. The clinical records of all the 15 patients were reviewed and analyzed. All patients fulfilled the five diagnostic requirements of hemophagocytic lymphohistiocytosis provided by the Familial Erythryophagocytic Histiocytosis (FEL) Study Group of the Histiocytic Society,12 including 1) fever (a duration of -7 days with a peak -38.5 C), 2) splenomegaly, 3) cytopenia (affecting -2 of 3 lineages in the peripheral blood), 4) hypertriglyceridemia (serum triglyceride .2.0 mmole/L), and 5) histopathological criteria (hemophagocytosis in bone marrow and/or lymph nodes without evidence of malignancies).
EBV Serological Studies The serological studies of EBV infection were investigated by standard virus serological assays,10 including the detection of anti-viral capsid antigen IgG and IgM (EBV-VCA IgG and IgM), anti-early antigen IgG (EBV-EA IgG) with indirect immunofluorescence method, and anti-nuclear antigen (EBNA) with anticomplement immunofluorescence method.
Histopathology and Immunohistochemistry The biopsy tissues of bone marrow, liver, and skin were paraffin embedded and processed for routine hematoxylin and eosin sections. The histomorphology of the sections were read under the light microscope. The characteristic histopathology of HS has been well described.1'5 For immunophenotypic studies of the lymphohistiocytic cells, paraffin block sections were cut at 6 p, deparaffinized, and immunostained with monoclonal antibodies UCHL-1 (CD45RO, pan-T antigen) and L26 (CD20, pan-B antigen) (Dako Corp., Santa Barbara, CA) using the avidin-biotin complex method (13).
(case 8) using a 30-bp oligonucleotide probe complementary to a portion of the EBV transcripts EBER1 14 Briefly, 10-p sections cut from paraffin blocks of formaldehyde- or B5-fixed tissues were deparaffinized, dehydrated, predigested with pronase, prehybridized at 42 C for 1 hour, and then hybridized with the digoxigenin-labeled probes overnight at a concentration of 0.25 ng/L. The slides were then washed in 4x sodium chloride and sodium citrate (SSC), 2x SSC, and 1 x SSC solution, followed by anti-digoxigenin antibody (Boehringer Mannheim, Mannheim, Germany) reaction for 30 minutes. The slides were then washed and the color products were developed by the nitroblue tetrazolium chloride/5bromo-4-chloro-3-indolyl-phosphate system. No nuclear counterstaining was performed. The B5-fixed tissue sections were pretreated with 1% iodine xylene solution before deparaffinization for 15 minutes to remove heavy metals. A dark pinkish or black color within the nucleus over background levels was considered a positive reaction. Suitable positive and negative controls were included in each run.
Double Labeling Immunohistochemistry and In Situ Hybridization Studies To define the immunophenotype of the lymphoid cells that contained the EBV transcripts EBER1, double labeling immunohistochemistry and in situ hybridization were performed according to the methods previously described (15). The paraffin sections were deparaffinized, rinsed in phosphate buffer, and then incubated with primary antibodies UCHL-1 and L26 for 40 minutes at room temperature in a humidity box. The streptavidin-biotin system (Zymed Laboratories, San Francisco, CA) was adopted. The color reaction was then developed using 3-amino 9-ethylcarbazole (Biomed Corp., Foster City, CA) as chromogen. The reaction was then stopped and followed subsequently by in situ hybridization for EBER1 transcripts as described above. The immunophenotypic staining was red in color and of membranous staining pattern, whereas the EBER 1 in situ hybridization products was dark pinkish to black in color and located in the nuclei.
Results
In Situ Hybridization
Brief Clinical Informations and Pertinent Laboratory Data
The EBV in situ hybridization studies were performed on bone marrow specimens of all 15 cases, on one liver biopsy specimen (case 6) and one skin biopsy
The brief clinical and laboratory information of the 15 patients were listed in Table 1. The patients' age of diagnosis ranged from 5 months to 14 years and 6
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Table 1. Brief Clinical and Laboratory Data of 15 Childhood Patients with Hemophagocytic Syndrome
EBV Serology
Case No.
Age/Sex
Fever Duration
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
0.9 y/F 5 M/F 3.4 y/F 14.6 y/F 2.7 y/F 3.1 y/F 2.8 y/F 5.0 y/M 1.3 y/F 4.3 y/F 7.6y/M 4.0 y/F 2.0y/F 4.6y/F 4.6 y/F
19 d 3m 31 d 2m 2m 12d 14 d 9d 10 d 38 d 33d 22 d 21 d 21 d 39 d
VGA IgM
IgG
EA
EBNA
EBV-ISH
1010101010-
1010160+ 640+ 320+
101010+ 20+ 10-
222+ 2+ 2-
-
Treatment
Outcome
IVIG, VP
D (23 d) A (2.8 y) D (67 d) D (2.5 m) + D (3.6 m) IVIG, VP 10+ 640+ 10+ 2+ IVIG A(1.7y) + 10+ 10+ 102D (70 d) IVIG, VP 2+ 10+ 10+ 10+ A (1.5 y) IVIG, VP 2+ VP 10+ 640+ 10+ A (1.4 y) 2+ 10640+ D (1.2 y) 160+ IVIG, VP 2+ + 101280+ 10IVIG,VP A(11m) 10+ 2+ + A (22 m) 160+ 10+ IVIG 2+ 1080+ 10+ IVIG, VP D(22 d) 2+ 10160+ 10_ IVIG, VP A(8 m) 10640+ ND ND D (117 d) IVIG, VP All 15 patients fulfilled the criteria of hemophagocytic lymphohistiocytosis provided by the Familial Erythrophagocytic Histiocytosis Study Group,12 including fever, splenomegaly, hypertriglyceridemia, cytopenia, and histopathologic criteria of hemophagocytosis in bone marrow and/or lymph nodes. VP VP VP
Abbreviations: d, day(s); m, month(s); y, year(s); D, died; A, alive; IVIG, intravenous immunoglobulin; VP, etoposide; VCA, viral capsid antigen; EA, early antigens; EBNA, nuclear antigens.
months (median, 3 years and 4 months). There were 2 males and 13 females. All patients were previously healthy without parental consanguity or any family history contributing to the disease. All patients had an acute onset of febrile illness, followed by skin rashes, pulmonary infiltrates, hepatosplenomegaly, jaundice, cytopenia, and coagulopathy and fulfilled the FELproposed criteria of hemophagocytic lymphohistiocytosis. The number of atypical lymphocytes in the peripheral blood was negligible in all patients, usually below 3%, distinct from the classical cases of infectious mononucleosis. An immunomodulation therapeutic regimen incorporating intravenous immunoglobulin (IVIG) and etoposide (VP-16) had been adopted to treat these patients since 1990 when the underlying pathogenesis of this disease has been clarified.7'8 Eight patients died of the fulminant disease and seven patients still survived after a mean follow-up period of 1 year and 2 months. The results are remarkably improved compared with the data of similar series we previously reported (8).
vanced stages of the disease usually showed severe depletion of normal hematopoietic elements with proliferation of phagocytosing histiocytes. Ten patients received multiple longitudinal marrow biopsies and phase progression was demonstrated from a hyperplastic marrow to a hypoplastic or depleted marrow in eight patients. The liver showed protal and sinusoidal infiltration of lymphocytes. The hepatic lobules revealed fatty change of hepatocytes with Kupffer cell hyperplasia and hemophagocytosis (Figure 2). The skin showed periadnexal and subcutaneous lymphohistocytic infiltration. The infiltrating lymphocytes in the marrow, liver, and skin were almost T lymphoid cells as revealed by the positive immunostaining for UCHL-1 (CD45RO). The L26 (CD20)-expressing lymphoid cells were negligible.
Histopathology and Immunophenotypic Studies
Thirteen of the 15 HS patients had serological evidence of either primary or active EBV infection. As shown in Table 1, patients 6 to 9 and 12 had a positive anti-VCA-lgM, indicating a primary EBV infection. Patients 5, 10, and 13 had a significant elevation of antiVCA IgG and a negative anti-EBNA, also suggesting a primary EBV infection. Patients 3, 4, 11, 14, and 15 had elevated titers of anti-VCA IgG and anti-EA and positive anti-EBNA, suggesting an active EBV infection. The remaining two patients (cases 1 and 2) had no positive serological response to EBV.
Bone marrow aspiration and histology in all patients showed varying degrees of atypical lymphoid cell infiltration, histiocytic reaction, and hemophagocytosis of erythrocytes and nucleated blood cells in at least one stage during their clinical courses (Figure 1). The bone marrow biopsies at early stage of the disease showed myeloid hyperplasia with negligible lymphohistiocytic reaction. However, the biopsies at the ad-
Serological Response to EBV
1222 Su et al A/P/tXne 1994, Vol. 144, No. 6
Figure 1. Bone marrou aspiration (A) and biopsy (B) showed florid lymphohistiocytosis with hemophagocytosis in mophagoc ytic syndrome.
a
childhood patient uwith
he-
Figure 2. Liver biopsy qf a pediatric patient with hemophagocytic syndrome showing infiltration of lymphocytes in the portal tracts, fatty chanige qbhepatocytes, and Knipffer cell hyper-
plasia.
In Situ Hybridization Scattered or extensive presence of dark granules, ranging from around 1 to 30% of total cells and representing the EBER1 transcripts, was detected in nine
marrow specimens (Table 1), in one liver biopsy (case 6), and in one skin biopsy (case 8), all in patients who were EBV-seropositive. In serial biopsies, the EBER1containing cells decreased significantly in two patients when the disease showed phase progression
EBV in Childhood VAHS 1223 AJPJune 1994, Vol. 144, No. 6
from a hyperplastic marrow to a depleted marrow at the terminal phase. In one patient who recovered from the disease, no more EBERl-positive cells could be detected in the second marrow biopsy. The varying degree of EBERl-positive cells in bone marrow in each case appear to correlate with the extent of lymphoid infiltrates and the phase of disease as described above. Four EBV-seropositive marrow specimens (cases 3, 4, 14, and 15) had no detectable EBER1 transcripts, probably due to the scanty lymphoid infiltrates in the marrow specimen. Both EBVseronegative marrow specimens had no detectable EBV transcripts EBER1.
Double Labeling Immunohistochemistry and In Situ Hybridization Studies In all nine EBERl-positive bone marrow (Figure 3A) and liver (Figure 3B) specimens, the EBERl-containing lymphoid cells expressed UCHL-1 (CD45RO) exclusively, indicating that T lymphoid cells contained the EBV transcripts. In contrast, none of the
EBERl-containing cells expressed B cell antigen L26 (CD20). A few CD45RO-expressing cells contained no EBER1 transcripts.
Discussion This study further confirm our previous observation that childhood HS in Taiwan is strongly associated with EBV.7 8 The young affected age of the patients (median, 3.4 years) and the serological response to EBV (positive anti-EBV-VCA IgM and/or the absence of EBNA antibodies in the presence of elevated antiEBV-VCA IgG) suggest that many of these childhood HS represent a fulminant form of primary EBV infection. The most surprising and important finding in this study is the demonstration of EBV transcripts EBERl in T cells in these childhood HS patients. Although EBV has been recently demonstrated to be associated with benign and malignant T lymphoproliferation,16-21 the lineage of EBV-infected cells in EBV-AHS has not been clarified. The EBV has been
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Figure 3. Double labeling immunobistochemistry and in situ hybridization or bone marrow (A) and liver (B) showed that the EBER1 transcriptscontaining (black nuclear granules) cells expressed UCHL-1 (CD45RO). ,
I
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AJPJune 1994, Vol. 144, No. 6
believed to infect B cells in classical cases of infectious mononucleosis.22,23 Classically, proliferating T cells in infectious mononucleosis represent a cytotoxic immune response to the EBV antigens expressed on EBV-containing B cells.22-24 The fulminant course of childhood HS patients pose one important question of whether the selected infection of T cells by EBV should be one of the factors responsible for the clinical features and the ominous outcome in EBV-AHS, distinct from the benign selflimiting course of classical infectious mononucleosis.25.26 The above assumption is supported by the recent observation of hemophagocytic syndrome in EBV-associated T cell lymphoma.18 Gaffey et al, however, has recently reported the infection of B cells by EBV in sporadic and familial hemophagocytic syndrome.27 Whether the immunophenotype of EBVinfected cells plays a role in the pathogenesis of HS should be clarified in the future. The patients with HS have been shown to have elevated levels of cytokines in the serum and the released cytokine has been presumed to account for the clinicopathological manifestations of HS.2&-30 Tumor necrosis factor has been presumed to be one of the most important cytokines responsible for the suppression of bone marrow and the disturbed lipid metabolism as observed in patients with EBV-AHS.3132 The sources of cytokines may be derived from activated T cells or macrophages.29 A complex interaction of cytokine release and host response, however, may exist in such patients. Two of our 15 patients had no serological evidence of EBV infection or detectable EBER1 transcripts in tissues, suggesting that other etiology or agents may exist in our childhood HS. Preliminary study had documented the association of human herpes virus type-6 with sporadic cases of childhood HS in Tai-
wan.33 The childhood EBV-AHS has been previously interpreted as histiocytic medullary reticulosis or malignant histiocytosis in Taiwan and some of the patients were treated with chemotherapeutic agents.7'8 The recognition of this disease entity as a fulminant or an atypical form of EBV infection has prompted us to adopt an immunomodulation treatment incorporating IVIG and etoposide for these childhood HS patients as previously recommended by other investigators.34-36 The incorporation of etoposide (VP-i6) in the regimen aims at the suppression of macrophage activation, which is the major pathobiological feature of HS.35 Compared with the results of our previous series of similar cases,8 a remarkable improvement of patients'
prognosis has been achieved in this study, providing a promising policy in the treatment of EBV-AHS patients.
References 1. Risdall RJ, McKenna RW, Nesbit ME, et al: Virusassociated hemophagocytic syndrome: a benign histiocytic proliferation distinct from malignant histiocytosis. Cancer 1979, 44:993-1002 2. Starkie CM, Kenny MW, Mann JR, et al: Histiocytic medullary reticulosis following acute lymphoblastic leukemia. Cancer 1981, 47:537-544 3. Reisman RP, Greco MA: Virus-associated hemophagocytic syndrome due to Epstein-Barr virus. Hum Pathol 1984, 15:290-293 4. Sullivan JL, Woda BA, Herrod HG, Koh G, Rivara FP, Muider C: Epstein-Barr virus-associated hemophagocytic syndrome virologic and immunopathological studies. Blood 1985, 65:1097-1104 5. Mroczek EC, Weisenburger DD, Grierson HL, Markin R, Purtilo DT: Fatal infectious mononucleosis and virus-associated hemophagocytic syndrome. Arch Pathol Lab Med 1987, 111:530-535 6. Cohen RA, Hutter JJ, Boxer MA, Goldman DS: Histiocytic medullary reticulosis associated with acute Epstein-Barr (EB) virus infection. Am J Pediatr Hematol Oncol 1980, 2:245-248 7. Su IJ, Hsieh HC, Lee CY: Histiocytic medullary reticulosis: a lethal form of primary EBV infection in young children in Taiwan. Lancet 1989, 1:389 8. Chen JR, Su IJ, Lin KH, et al: Fulminant childhood hemophagocytic syndrome mimicking histiocytic medullary reticulosis: an atypical form of Epstein-Barr virus infection. Am J Clin Pathol 1991, 96:171-176 9. Wilson MS, Weiss LM, Gatter KC, Mason DY, Dorfman RF, Warnke RA: Malignant histiocytosis: a reassessment of cases previously reported in 1975 based on paraffin section immunophenotyping. Cancer 1990, 66:530-536 10. Lin KH, Chiang CH, Yang CS: Age distribution and Epstein-Barr virus, cytomegalovirus, and rubella virus antibodies. J Formosan Med Assoc 1987, 86:13161319 11. McClain K, Gehrz R, Grierson H, Purtilo D, Filipovich A: Virus-associated histiocytic proliferations in children: frequent association with Epstein-Barr virus and congenital or acquired immunodeficiencies. Am J Pediatr Hematol Oncol 1988, 10:196-205 12. Henter JI, Elinder G, Ost A, FHL Study Group of the Histiocytic Society: Diagnostic guidelines for hemophagocytic lymphohistiocytosis. Semin Oncol 1991, 18: 29-33 13. Hsu SM, Raine L, Fanger H: Use of avidin-biotinperoxidase complex (ABC) in immunoperoxidase techniques: a comparison between ABC and unlabelled antibody (PAP) procedures. J Histochem Cytochem 1981, 29:577-585
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14. Weiss LM, Faffe E, Liu XF, Chen YY, Shibata D, Medeiros LJ: Detection and localization of Epstein-Barr virus genomes in angioimmunoblastic lymphadenopathy and angioimmunoblastic lymphadenopathy-like lymphoma. Blood 1992, 79:1789-1795 15. Korbjuhn P, Anagnostopoulos I, Hummel M, Tiemann M, Dallenbach F, Parwaresch MR, Stein H: Frequent latent Epstein-Barr virus infection of neoplastic T cells and bystander B cells in human immunodeficiency virus-negative European peripheral pleomorphic T-cell lymphomas. Blood 1993, 82:217-223 16. Yoneda N, Tatsumi E, Kawanishi M, Teshigawara K, Yamamura Y, et al: Detection of Epstein-Barr virus genome in benign polyclonal proliferative T cells of a young male patient. Blood 1990, 76:172-177 17. Ishihara S, Tawa A, Yumura-Yagi K, Murata M, Hara JI, Yabuuchi H, et al: Clonal T cell lymphoproliferation containing Epstein-Barr (EB) virus DNA in a patient with chronic active EB virus infection. Jpn J Cancer Res 1989, 80:99-104 18. Su IJ, Hsu YH, Lin MT, Cheng AL, Wang CH, Weiss LM: Epstein-Barr virus-containing T cell lymphoma presents with hemophagocytic syndrome mimicking malignant histiocytosis. Cancer 1993, 72:909-916 19. Su IJ, Hsieh HC, Lin KH, et al: Aggressive peripheral T cell lymphoma containing Epstein-Barr virus DNA: a clinicopathological and molecular analysis. Blood 1991, 77:799-808 20. Craig FE, Clare CN, Sklar JL, Banks PM: T cell lymphoma and the virus-associated hemophagocytic syndrome. Am J Clin Pathol 1992, 97:189-194 21. Jones JF, Shurin S, Abramowsky C, et al: T-cell lymphomas containing Epstein-Barr virus DNA in patients with chronic Epstein-Barr virus infection. N EngI J Med 1988, 318:733-741 22. Svedmyr E, Jondal M: Cytotoxic effector cells specific for B cell lines transformed by Epstein-Barr virus are present in patients with infectious mononucleosis. Proc Natl Acad Sci USA 1975, 72:1622-1626 23. Reedman M, Klein G: Cellular localization of an Epstein-Barr Virus (EBV)-associated complementfixing antigen in producer and nonpraducer lymphoblastoid cell lines. Int J Cancer 1973, 11:499-520 24. Thorley-Lawson DA: Immunologic response to Epstein-Barr virus infection and the pathogenesis of EBV-induced diseases. Biochim Biophys Acta 1988, 948:263-286
25. Henle G, Henle W: Observations on childhood infections with the Epstein-Barr virus. J Infect Dis 1970, 121:303-310 26. Thorley-Lawson DA: Immunologic response to Epstein-Barr infectioni and the pathogenesis of EBVinduced diseases. Biochim Biophys Acta 1988, 948: 263-286 27. Gaffey MJ, Frierson HF, Medeiros LJ, Weiss LM: The relationship of Epstein-Barr virus to infection-related (sporadic) and familial hemophagocytic syndrome and secondary (lymphoma-related) hemophagocytosis: an in situ hybridization study. Hum Pathol 1993, 24:657-667 28. Henter JI, Elinder G, Soder 0, Hansson M, Andersson B, Andersson U: Hypercytokinemia in familial hemophagocytic syndrome. Blood 1991, 78:2918-2922 29. Fugiwara F, Hibi S, Imashuku S: Hypercytokinemia in hemophagocytic syndrome. Am J Pediatr Hematol Oncol 1993, 15:92-98 30. Tchernia G, Mirica C, Delfraissy JF: Histiocytic medullary reticulosis: A lethal form of primary EBV infection. Lancet 1989, 1:1265-1266 31. Ohga S, Matsuzaki A, Nishizaki M, Nagashima T, Kai T, Suda M, Ueda K: Inflammatory cytokines in virusassociated hemophagocytic syndrome: interferongamma as a sensitive indicator of disease activity. Am J Pediatric Hematol Oncol 1993, 15:291-298 32. Feingold K, Soued M, Staprans I, Gavin LA, Donahue ME, Huang BJ, Moser AH, Gulli R, Grunfeld C: Effect of tumor necrosis factor (TNF) on lipid metabolism in the diabetic rat: evidence that inhibition of adipose tissue lipoprotein lipase activity is not required for TNFinduced hyperlipidemia. J Clin Invest 1989, 83:11161121 33. Huang LM, Lee CY, Kin KH, et al: Human herpes virus-6-associated with hemophagocytic syndrome. Lancet 1990, 336:60-61 34. Goulder P, Seward D, Hatton C: Intravenous immunoglobulin in virus-associated hemophagocytic syndrome. Arch Dis Child 1990, 65:1275-1277 35. Ambruso DR, Hays T, Zwartjes WJ, Tubergen DG, Favara BE: Successful treatment of lymphohistiocytosis with epipodophyllotoxin VP16-213. Cancer 1980, 45: 2516-2520 36. Nydegger UE: Intravenous immunoglobulin in combination with other prophylactic and therapeutic measures. Transfusion 1992, 32:72-82.
