Homing potentials of circulating antibody-secreting cells after administration of oral or parenteral protein or polysaccharide vaccine in humans

The site of antigen encounter influences the Ig-distribution and homing pot entials of circulating antibody-secreting cells (ASC) induced. After oral a ntigen administration, the majority ASC secrete the mucosal Ig-isotype, IgA , and all of them express the gut homing receptor (HR), alpha(4)beta(7), th us implying mucosal homing of these cells. Parenteral protein vaccine induc es an IgG-dominated response with a low proportion of alpha(4)beta(7) expre ssing cells. However, a polysaccharide vaccine, even if administered parent erally, elicits an IgA-dominated response, hence suggesting homing to the m ucosa. In order to study the influence of the nature of the antigen on the targeting of the ASC response, the present work compares the homing potenti als of circulating ASC in humans after administration of an oral Salmonella Typhi Ty21a vaccine (antigen studied: O-9,12 polysaccharide), an oral reco mbinant cholera vaccine (antigen studied: cholera toxin B-subunit, CTB prot ein), a parenteral pneumococcal vaccine (antigen studied: Pnc capsular poly saccharide 19F) or a parenteral tetanus toroid vaccine (antigen studied: TT protein), alpha(4)beta(7) was expressed on a higher proportion of ASC indu ced by oral O-9,12 (99%) and CTB (99%) than by parenteral Pnc (70%) or TT ( 63%). L-selectin, the peripheral lymph node HR, was expressed on a smaller proportion of ASC induced by O-9,12 (37%) or CTB (43%) than of those induce d by Pnc (78%) or TT (81%). The results imply that even if the nature of th e antigen has a profound effect on the Ig-distribution of the ASC response, it does not seem to influence the targeting of the response. (C) 1998 Else vier Science Ltd. All rights reserved.