Affiliations: Department of Pediatrics, Federal University of São
Paulo, São Paulo, Brazil | Department of Medicine, Federal University of São
Paulo, São Paulo, Brazil
Note: [] Correspondence: M. Isabel de Moraes-Pinto, Division of Pediatric
Infectious Diseases, Federal University of São Paulo, Rua Pedro de Toledo,
781 9 andar 04039-032, São Paulo SP, Brazil. Tel.: +55 11 5574 6471 / 5571
2944; Fax: +55 11 5575 6928; E-mail: m.isabelmp@uol.com.br
Abstract: Diagnosis of primary immunodeficiency diseases (PID), based on
laboratory tests and assessment of T lymphocyte function, is crucial in
patients who present with lymphopenia. We evaluated T lymphocyte function in
healthy children and adults and in patients and with PID using flow cytometry.
Whole blood cultures were stimulated with phytohemagglutinin, purified protein
derivate (PPD) and candidin, followed by detection of intracellular
interferon-gamma (IFN - gamma) and CD25 membrane expression on
CD3+ T cells by flow cytometry. Flow cytometry results were
compared with 3H-thymidine (3HTdR) lymproliferation after in vitro cell
stimulation and with delayed type hypersensitivity reaction (DTH). Patients
with PID had lower intracellular IFN - gamma production than healthy children
and healthy adults after PHA stimulation for 18 h (p=0.024
and p<0.0001, respectively); CD25 expression was also lower
in patients with PID than in healthy children and adults after candidin
stimulation (p=0.048 and p< 0.0001,
respectively). CD25 expression after PPD and candidin stimulation were also
higher in healthy adults when compared with both patients and with healthy
children (p< 0.0001 for all comparisons).
Lymphoproliferation assay with 3HTdR after candidin stimulation did not show
any significant difference between healthy children and patients with PID, but
the response was higher in healthy adults (p=0.029). The
DTH for PPD was not different between PID and healthy children
(p=0.281). Intracellular IFN-gamma after PHA stimulation
for 18 h and CD25 membrane expression after candidin stimulation for 72 h on
CD3+ T cells were most reliable parameters that could
discriminate PID patients from healthy children. Our results confirm the high
variability in functional cell assays and reinforce the idea that age
differences must be taken into consideration during assay evaluation.
