(a) Total anti-ovalbumin (OVA) serum IgG levels after immunisation using either microneedle (MN) or conventional intradermal administration (ID). Mice were treated with OVA-loaded MN, with or without IMI (OVA MN and OVA + IMI), IMI plus MN (IMI MN) or blank MN (blank MN). Mice treated by conventional ID injections received OVA (OVA ID), OVA plus IMI (OVA + IMI ID), IMI (IMI ID) and PBS (PBS ID). Animals were bled on days 14, 47 and 70. Data are presented as mean ± standard deviation (SD), n = 4. (For reference to the statistical significances, please refer to the main text.) Humoral and cellular immune responses elicited in mice following immunisation via MN or ID was determined in sera (b, c) or in cultured splenocytes (d, e). The titres of total anti-OVA IgG subclasses (b, c), as well as IL-4 (d) and IFN- γ (e) cytokines are presented. Mice were treated with OVA-loaded MN, with or without IMI (OVA MN and OVA + IMI), IMI plus MN (IMI MN) or blank MN (blank MN). Mice treated by ID were injected with solutions of OVA (OVA ID) or OVA plus IMI (OVA IMI). Data are presented as means ± SD. In the case of IgG1, n = 4; IgG2a, n = 2; IFN- γ, n = 2; IL-4, n = 4.