Naive and memory T cells in hypertrophied adenoids in children according to age

The anatomic location of the adenoid implies that this organ is the first site of contact with inhaled antigens. Depending on the expression of different isoforms of the CD45 molecules, T cells can be divided into naive (CD45RA(+)) and memory (CD45R0(+)) cells, the latter representing T cells that have already been exposed to antigens. The purpose of this study was to analyse the lymphoid cells' subsets in adenoids and relate the findings to the, age. The analysed material was adenoid tissue removed on the grounds of hypertrophy from 22 children. The patients were divided into two groups: up to 5 and above 5 years of age. The analyses of the lymphocytes subpopulations in the adenoid were performed in an EPICX XL (Coulter) flow cytometry. The results are expressed as the percentage of positively labeled cells (CD4(+), CD8(+), CD4(+)/CDB+, CD4(+)CD45RA(+), CD8(+)CD45RA(+), CD4(+)CD45RO(+), CD8(+)CD45RO(+)). The percentage of CD4(+)/CD45RO(+) in children up to 5 years of age was significantly lower than in older children. We found the positive regression between age and the percentage of CD4(+) cells was CD45R0(+) (r = 0.64). There were no statistically significant differences between study subgroups for the other parameters. The positive regression for CD4(+)/CD45RO(+) cells and age may result from increased stimulation by bacterial, viral and other antigens. Our results indicate that the adenoid have an important role in the development of an immunological memory among younger children. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.