Our aim was to study whether the aberrant amount or function of
regulatory T cells is related to the development of type 1 diabetes
(T1D) in children. We also set out to investigate the balance of
different T cell subtype markers during the T1D autoimmune process. Treg
cells were quantified with flow cytometric assay, and the suppression
capacity was analysed with a carboxyfluorescein succinimidyl ester
(CFSE)-based T cell suppression assay in children in various phases of
T1D disease process and in healthy autoantibody-negative control
children. The mRNA expression of different T cell subpopulation markers
was analysed with real-time qPCR method. The proportion and suppression
capacity of regulatory T cells were similar in seroconverted children at
an early stage of beta cell autoimmunity and also in children with T1D
when compared to healthy and autoantibody-negative children. Significant
differences were observed in the mRNA expression of different T cell
subpopulation markers in prediabetic children with multiple (≥2)
autoantibodies and in children with newly diagnosed T1D when compared to
the control children. In conclusion, there were no quantitative or
functional differences in regulatory T cells between the case and
control groups in any phase of the autoimmune process. Decreased mRNA
expression levels of T cell subtype markers were observed in children
with multiple islet autoantibodies and in those with newly diagnosed
T1D, probably reflecting an exhaustion of the immune system after the
strong immune activation during the autoimmune process or a generally
aberrant immune response related to the progression of the disease.