Influenza-specific and total-IgG ASCs were enumerated by Elispot and flow cytometry daily in the blood in 6 healthy adults after trivalent influenza vaccination (TIV).
Peak H1-specific IgG ASC frequencies occurred variably from day 5 to 8 and correlated with the fold-rise rise in hemagglutination inhibition (HAI titers); r = 0.91, p = 0.006. H3-specific IgG ASC frequencies correlated less well, perhaps due to a mismatch of the H3 protein in the vaccine and that used in the Elispot assay. Peak frequencies of vaccine-specific and total-IgG ASCs were 0.3 % and 0.8 % , respectively, of peripheral blood mononuclear cells (PBMC). Peak TIV-, H1-, H3-, and total-IgG ASC frequencies were 1736 ± 1133, 626 ± 520, 592 ± 463, and 4091 ± 2019 spots/106 PBMC, respectively. Peak TIV-, H1-, and H3-specific IgG ASC of total-IgG ASC frequencies constituted 63 % ± 21, 26 % ± 10, 22 % ± 17, respectively.
After immunization with inactivated influenza vaccine the peak in influenza-specific ASC frequencies is variable but correlates well with the magnitude of protective HAI responses.