IN-VIVO CLONAL DOMINANCE AND LIMITED T-CELL RECEPTOR USAGE IN HUMAN CD4(-CELL RECOGNITION OF HOUSE-DUST MITE ALLERGENS() T)

Sensitivity to house dust mite antigens in atopic individuals is a maj or cause of aliergic diseases, ranging from asthma to rhinitis and der matitis. We have studied the T-cell receptor (TCR) usage of house-dust -mite-specific CD4+ T-cell clones isolated from an atopic individual, by using the anchored polymerase chain reaction, and have analyzed the peripheral TCR repertoire of the same individual. Several T-cell clon es had identical TCRs at the sequence level, despite the fact that the y had been independently isolated, in some cases, in different years. These data suggest the presence in vivo of long-lived T-cell clones. W e have also shown that junctional sequences identical to these clones are present in peripheral blood T cells taken 6 years after the isolat ion of the T-cell dones. The analysis of TCR genes used by the panel o f clones reveals oligoclonality, with the variable (V) region gene seg ments Valpha8 and Vbeta3 being dominant, although there is minimal con servation of junctional sequences. The results have implications for u nderstanding the TCR recognition of an environmental aeroallergen and the life span of T-cell clones in vivo during a chronic immune respons e.