ABSTRACT
In order to determine the role of memory/naive T cells in atopic allergy patients we analyzed peripheral blood mononuclear cells before and during the grass pollen season. The study comprised 28 patients with seasonal symptoms of atopic allergy and 18 with perennial symptoms. Flow cytometry was employed to detect the expression of CD3, CD4, CD4CD45RA, CD4CD45RO, CD8, CD16, and CD19 molecules on peripheral blood lymphocytes. Allergic patients showed a decreased proportion of memory (CD4+CD45RO+) T cells compared with healthy subject (p < 0.05). The proportion of naive (CD4+CD45RA+) helper T cells did not differ between allergic patients and controls. The percentage of CD4+CD45RO+ cells increased during natural antigen exposure (grass pollen season) in allergic patients with seasonal symptoms. The results show at least two important observations. A potential homing tendency to nasal, bronchial and conjunctival mucosa of memory T cells (CD45RO) in atopic allergy patients may explain their deficiency in peripheral blood. Secondly, the grass pollen season may switch their phenotype from naive into memory T cells causing the increase of CD45RO cells. These events do not occur in non-allergic individuals and may thus constitute new insight into the basic mechanism of atopic allergy.
