A new intra-NALT route elicits mucosal and systemic immunity against Moraxella catarrhalis in a mouse challenge model

Mucosally administered antigens are often poorly immunogenic due to the difficulty of transporting antigens through the mucosal epithelium. We investigated a new route of intranasal-associated lymphoid tissue (intra-NALT) administration of antigens to circumvent the antigen transportation barrier. A comparative study was carried out on mice administered with killed whole cells of Moraxella catarrhalis strain 25238 plus cholera toxin (CT) by intra-NALT injection and nasal inoculation. Both routes induced significant elevations of several isotype antibodies against strain 25238 in saliva, lung lavage, and serum as measured by an enzyme-linked immunosorbent assay (ELISA). Most of these antibodies were paralleled by the numbers of their corresponding antibody forming cells in mucosal or systemic lymphoid tissues. However, intra-NALT injection elicited higher levels of immunoglobulin (Ig) A and IgG in saliva, IgA and IgG in lung lavage, and IgG and IgM in sera than nasal inoculation (P