Expression of chemokine receptors by lung T cells from normal and asthmatic subjects

The lung is an important tertiary lymphoid organ with constant trafficking of T cells through the lung in both health and disease. T cell migration is controlled by a combination of adhesion receptors and chemokines expressed on vascular endothelium and in the tissue, often in an organ-specific mann er. This leads to selective accumulation of different T cell subsets, a pro cess called lymphocyte homing. There is evidence for a distinct lung-homing pathway, but no specific lung-homing receptors have been described. We ana lyzed the chemokine receptor profile of lung T cells to determine the exten t to which lung T cells shared homing pathways with other organs such as th e gut and skin. In addition, we compared expression of receptors in normal and asthmatic individuals to determine whether different pathways were used in health and disease, We observed that lung T cells expressed a profile o f chemokine and adhesion receptors distinct from that of gut- and skin-homi ng T cells although no chemokine receptor specific for the lung was found. In particular, lung T cells expressed CCR5 and CXCR3, but not CeR9 or cutan eous lymphocyte Ag, and only low levels of CCR4 and alpha (4)beta (7). No d ifferences were observed between lung T cells from normal vs asthmatic subj ects. This study provides added support far the concept of a lung-homing pa thway separate from other mucosal organs such as the gut and suggests that the chemokine pathways that control T cell migration in normal homeostasis and Th2-type inflammatory responses are similar.