Detection and quantification of CD4(+) T cells with specificity for a new major histocompatibility complex class II-restricted influenza A virus matrix protein epitope in peripheral blood of influenza patients

FVFTLTVPS was identified as the core sequence of a new major histocompatibi lity complex class II-restricted T-cell epitope of influenza virus matrix p rotein. Epitope-specific CD4(+) T cells mere detected in the peripheral blo od of patients with frequencies of up to 0.94%, depending on the number of additional terminal amino acids.