Comparative studies of local antibody and cellular immune responses to influenza infection and vaccination with live attenuated reassortant influenza vaccine (LAIV) utilizing a mouse nasal-associated lymphoid tissue (NALT) separation method

The first and most significant barrier against influenza infection is the mucosal-associated lymphoid tissue of the upper airways and rodent nasopharyngeal-associated lymphoid tissue (NALT) is considered equivalent to the lymphoid tissue of human Valdryer's ring. This study is the first attempt to analyze and compare local and systemic cellular and antibody immune responses in NALT and spleen in a mouse model of experimental influenza infection and intranasal vaccination with LAIV (live attenuated reassortant influenza vaccine). It was shown that the vaccine strain completely inherited the ability to induce high-grade local antibody responses (secretory IgA + IgG + IgM), local cellular lymphoproliferative activity, CD4⁺, CD8⁺ and CD19⁺ lymphocyte and cytokine production responses from the virulent parental strain but it had less capacity to stimulate production of serum IgG, accumulation of CD8⁺ cells and IFN-γ production in the spleen. Primary non-complicated influenza infection and primary vaccination were accompanied by a short-term (24 h) increase in the levels of lymphocyte apoptosis in both NALT and spleen. However, experimental data indicated that vaccination with LAIV and uncomplicated forms of influenza infection did not influence immune system apoptosis following a secondary immune response.