title: Lymphocyte transformation assay for C neoformans antigen is not reliable for detecting cellular impairment in patients with neurocryptococcosis.
abstract: BACKGROUND
  Cryptococcus neoformans causes meningitis and disseminated infection in healthy individuals, but more commonly in hosts with defective immune responses. Cell-mediated immunity is an important component of the immune response to a great variety of infections, including yeast infections. We aimed to evaluate a specific lymphocyte transformation assay to Cryptococcus neoformans in order to identify immunodeficiency associated to neurocryptococcosis (NCC) as primary cause of the mycosis.
  
  
  METHODS
  Healthy volunteers, poultry growers, and HIV-seronegative patients with neurocryptococcosis were tested for cellular immune response. Cryptococcal meningitis was diagnosed by India ink staining of cerebrospinal fluid and cryptococcal antigen test (Immunomycol-Inc, SP, Brazil). Isolated peripheral blood mononuclear cells were stimulated with C. neoformans antigen, C. albicans antigen, and pokeweed mitogen. The amount of 3H-thymidine incorporated was assessed, and the results were expressed as stimulation index (SI) and log SI, sensitivity, specificity, and cut-off value (receiver operating characteristics curve). We applied unpaired Student t tests to compare data and considered significant differences for p<0.05.
  
  
  RESULTS
  The lymphotoxin alpha showed a low capacity with all the stimuli for classifying patients as responders and non-responders. Lymphotoxin alpha stimulated by heated-killed antigen from patients with neurocryptococcosis was not affected by TCD4+ cell count, and the intensity of response did not correlate with the clinical evolution of neurocryptococcosis.
  
  
  CONCLUSIONS
  Response to lymphocyte transformation assay should be analyzed based on a normal range and using more than one stimulator. The use of a cut-off value to classify patients with neurocryptococcosis is inadequate. Statistical analysis should be based on the log transformation of SI. A more purified antigen for evaluating specific response to C. neoformans is needed.
authors.affiliation: Laboratório de Dermatologia and Immunodeficiências, Departmento de Dermatologia, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, Brazil. katyarocha20@yahoo.com.br
authors.forename: Katya C
authors.initials: KC
authors.lastname: Rocha
authors.forename: Cinthia
authors.initials: C
authors.lastname: Pinhal
authors.forename: Sônia
authors.initials: S
authors.lastname: Cavalcanti
authors.forename: Monica S M
authors.initials: MS
authors.lastname: Vidal
authors.forename: Matheus
authors.initials: M
authors.lastname: Toscano
authors.forename: Dewton
authors.initials: D
authors.lastname: Moraes-Vasconcelos
authors.forename: Alberto J S
authors.initials: AJ
authors.lastname: Duarte
authors.forename: Fernando L A
authors.initials: FL
authors.lastname: Fonseca
authors.forename: Luiz Carlos
authors.initials: LC
authors.lastname: de Abreu
authors.forename: Vitor E
authors.initials: VE
authors.lastname: Valenti
authors.forename: Anete S G
authors.initials: AS
authors.lastname: Grumach
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000946:Antigens, Fungal / Q000276:immunology*; D003455:Cryptococcus neoformans / Q000276:immunology*; D005260:Female; D006801:Humans; D008213:Lymphocyte Activation / Q000502:physiology*; D008297:Male; D016919:Meningitis, Cryptococcal / Q000276:immunology*; D008875:Middle Aged; D055815:Young Adult
chemical_list: D000946:Antigens, Fungal