Age related differences in humoral immune response to respiratory syncytial virus infection in adults

The humoral immune response to Respiratory Syncytial Virus (RSV) was investigated in old and young adults. RSV was identified by culture and/ or reverse transcription polymerase chain reaction (RT-PCR) in 52 elderly (mean age 74 years) and 15 young adults (mean age 33 years) with respiratory illness. Preinfection serum neutralizing and binding antibody levels were similar in the two age groups, although older persons had significantly greater serum neutralizing responses to group A RSV (log(2) 2.8 increase vs. 1.7, P = 0.001) and group B RSV (log(2) 2.8 vs. 1.3, P = 0.0008). Older persons also had significantly increased responses to the RSV F (log(2) 2.9 vs. 1.1, P < 0.0001), Ga (log(2) 2.1 vs. 1.3, P = 0.0007), and Gb proteins (log(2) 2.7 vs. 1.4, P = 0.0004). The exuberant antibody response seen in older adults may be a reflection of greater viral load and antigenic stimulation and/or a shift from Th1 to Th2 dominant immune response with aging. The relationship of immune response to disease pathogenesis in older persons deserves further study.