FIG. 2.

Conjugation of antigen to CTB enhances antigen presentation in vitro. Spleen cells were incubated with antigen in free form or conjugated to CTB together with purified antigen-specific TCR-transgenic T cells. Data are expressed as the proliferative responses obtained in response to free or CTB-conjugated whole OVA (A), OVA peptide (B), or HA peptide (C). (A) APC and OVA-specific TCR-transgenic T cells were incubated with 10⁻⁸ M OVA or OVA-CTB or 10⁻⁸ M OVA plus 6 × 10⁻⁹ M CTB. (B) APC and OVA-specific TCR-transgenic T cells were incubated with graded amounts of OVA peptide (□) or with CTB-conjugated OVA peptide (■). (C) APC and HA-specific TCR-transgenic T cells were incubated with graded amounts of free HA peptide (□), CTB-conjugated HA peptide (●), or the equivalent amounts of unconjugated HA peptide and CTB (○).