Could ADCC Predict Flu Vaccine Responsiveness in Older Adults?

Baseline antibody-dependent cellular cytotoxicity (ADCC) is not predictive of hemagglutination inhibiting (HAI) vaccine responsiveness in older adults who receive the influenza vaccine, indicating that alternate measures of vaccine responses in this patient population are still needed, according to a recent study.

Although older adults have an increased risk of influenza, they generally do not respond well to vaccination. However, previous evidence has suggested that ADCC may play a role in protection against influenza in this patient population.
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To explore this further, the researchers evaluated sera samples from 3 groups of participants who received the 2008-2009 seasonal trivalent influenza vaccine (TIV). All patients included in the study had pre-existing HAI antibodies and either no, low, or high HAI responses induced by TIV.

Fc receptor cross-linking, natural killer (NK) cell activation, and influenza-infected cell killing were used to assess serum ADCC activity.

Results indicated that, although most participants with TIV-induced no, low, or high response had detectable ADCC antibodies prior to vaccination, baseline ADCC did not predict HAI vaccine responsiveness. However, the researchers noted that ADCC and HAI responses tracked closely across all groups, against all 3 TIV hemagglutinins, and in all ADCC assays that were tested.

“Older adults commonly have pre-existing ADCC antibodies in the absence of high HAI titers to circulating influenza strains,” the researchers concluded. “In older vaccinees, ADCC response mirrored HAI antibodies and was readily detectable despite high postvaccination HAI titers. Alternate measures of vaccine responsiveness and improved vaccinations in this at-risk group are needed.”

—Christina Vogt

Reference:

Vanderven HA, Jegaskanda S, Wines BD, et al. Antibody-dependent cellular cytotoxicity responses to seasonal influenza vaccination in older adults. J Infect Dis. 2017;217(1):12-23. https://doi.org/10.1093/infdis/jix554.