title: Heterogeneity of immune markers in hemophagocytic lymphohistiocytosis: comparative study of 9 familial and 14 familial inheritance-unproved cases.
abstract: OBJECTIVE
  Although immune dysfunction is suspected in patients with hemophagocytic lymphohistiocytosis (HLH), the difference between immune dysfunction in patients with familial erythrophagocytic lymphohistiocytosis (FEL) and familial inheritance-unproved lymphohistiocytosis (FIU) remains unknown. The aim of this study was to determine useful markers to distinguish patients with FEL from those with FIU.
  
  
  METHODS
  Clinical features and laboratory findings, especially natural killer (NK) cell activity and the relative frequencies of peripheral blood mononuclear cell (PBMC) subsets, and serum levels of interferon-gamma and soluble interleukin-2 receptor were compared in 9 patients with FEL and 14 age-matched patients with FIU. Twenty-seven healthy infants served as controls. The treatment and outcome were also compared for patients with FEL and FIU.
  
  
  RESULTS
  Comparison between patients with FEL and FIU revealed significantly lower NK activity in those with FEL (p = 0.03) but failed to show any significant differences in PBMC subsets, except that the percentage of CD3+ T cells was higher in patients with FEL (p = 0.02). CD4- and CD8-dominant phenotypes were characteristic findings in both groups of patients, although increased CD19+ B cells were restricted to patients with FIU. NK activity was deficient (< 5%) in four of the seven patients with FEL tested but in only one of eight patients with FIU. By comparison to values for age-matched controls, the percentages of CD3+, CD3+DR+ and CD45RO+ PBMCs in patients with FEL were significantly high (p < 0.05) and those of CD19+ and CD45RA+ subsets were lower than normal. Among patients with FIU, PBMC subsets included significantly reduced CD3+, CD4+, CD45RA+, and CD4+CD45RA+. In this small series, the outcome of patients with FEL and FIU treated with chemotherapy was not significantly different at the time of evaluation.
  
  
  CONCLUSIONS
  These results indicate considerable immune heterogeneity among patients with HLH younger than 2 years. Although NK activity was useful but not diagnostic, determination of PBMC subsets and patterns of cytokine expression was not helpful in distinguishing patients with FEL from those with FIU, suggesting that the immune responses characteristic of these diseases may reflect different triggering factors, including viruses. The impact of this immune heterogeneity on patients' outcome remains to be determined.
authors.affiliation: Division of Pediatrics, Children's Research Hospital, Kyoto Prefectural University of Medicine, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Imashuku
authors.forename: S
authors.initials: S
authors.lastname: Hibi
authors.forename: M
authors.initials: M
authors.lastname: Sako
authors.forename: T
authors.initials: T
authors.lastname: Ishii
authors.forename: U
authors.initials: U
authors.lastname: Kohdera
authors.forename: K
authors.initials: K
authors.lastname: Kitazawa
authors.forename: K
authors.initials: K
authors.lastname: Ooe
authors.forename: M
authors.initials: M
authors.lastname: Naya
authors.forename: H
authors.initials: H
authors.lastname: Sawada
authors.forename: T
authors.initials: T
authors.lastname: Kawakami
mesh_terms: D015703:Antigens, CD / Q000032:analysis*; D015415:Biomarkers; D016207:Cytokines / Q000378:metabolism; D005260:Female; D015616:Histiocytosis, Non-Langerhans-Cell / Q000235:genetics* / Q000276:immunology*; D006801:Humans; D016130:Immunophenotyping; D007223:Infant; D007231:Infant, Newborn; D007694:Killer Cells, Natural / Q000276:immunology*; D016131:Lymphocyte Subsets / Q000276:immunology*; D008297:Male
chemical_list: D015703:Antigens, CD; D015415:Biomarkers; D016207:Cytokines