Table 1.

Signature immunological changes in pTfh and B cells in vaccine responders (VRs) following influenza vaccine at TO (baseline), T1 (7 days), and T2 (4 weeks).

Changes in pTfh cell compartment in vaccine responders Antigen induced IL-21 gene expression at TO Expansion of pTfh at T1, T2 Ag-stimulated intracellular IL-21 production in pTfh at T2 “Help” to autologous B cells for H1N1-specific IgG production and B cell differentiation in pTfh plus B cell cocultures at T2

B cell changes in vaccine responders Increase in frequencies of plasmablasts at T1 Increase in spontaneous H1N1-specific ASC at T1 Increase in memory B cells and switch memory at T2 Upregulation of IL-21R on total B and memory B cells at T2 Increase in TACI expression on total B and memory B cells at T2 Downregulation of BAFT-R expression on total B and memory B cells at T2

PBMC culture sups/plasma findings in vaccine responders Production of IL-21 and CXCL13 in H1N1-stimulated culture sups with increases in plasma IL-21 Increase in plasma BAFF and APRIL levels

pTfh, peripheral T follicular helper; PBMCs, peripheral blood mononuclear cells; Ab, antibody; BAPF-R, B cell activating factor receptor; APRIL, a proliferation inducing ligand; CXCL13, C-X-C motif chemokine ligand 13; ASCs, antibody secreting cells.