OVA Peptide (323-339) represents a T and B cell epitope of OVA, which is important in the generation and development of immediate hypersensitivity responses in BALB/c mice. Daily aerosolization of OVA Peptide (323-339) for 20 minutes over a period of 10 days has been as effective in the stimulation of a serum anti-OVA IgE antibody response as sensitization to native OVA by the same route. After sensitization to native OVA, the majority of the IgE anti-OVA response is directed against OVA Peptide (323-339). Evaluated by hematoxylin/eosin and major basic protein immunohistochemical stainings, OVA and OVA Peptide (323-339) induce similar lung inflammation. Interestingly, significant serum total IgE and OVA-specific IgE are observed in OVA mice when compared to saline control. OVA Peptide (323-339) mice show higher serum OVA-specific IgE, OVA Peptide (323-339)-specific IgE, IL-4 and lower IFN-γ similar to OVA mice. The proliferative response to OVA is found in cultured splenocytes of both OVA and OVA Peptide (323-339) mice, while the similar proliferative response to OVA Peptide (323-339) is only observed in the splenocytes of OVA Peptide (323-339)-sensitized and challenged mice. Although OVA Peptide (323-339) induces a Th2-like response in the mouse model as does OVA, OVA Peptide (323-339) has clearly limited immunogenic potency to activate OVA-sensitized and challenged mice splenocytes, unlike OVA^[2].