Optimization of antigen presentation to T cell hybridomas by purified Ia molecules in planar membranes. Ia molecule polymorphism determines the antigenic fine specificity of the response to cytochrome c peptides

Ia molecule (E_β^k,b : E_α^k or A_β^k : A_α^k)-containing planar membranes were constructed with cholesterol and a 9 : 1 molar ratio of the phospholipids dipalmitoyl phosphatidylcholine and dilinoleoyl phosphatidylcholine. This lipid composition was found to be optimal for the stimulation of T cell hybridomas of different specificities. Use of this system allowed the detection of weak responses not measurable when other artificial membranes were used. Activation of the cytochrome c E_α^k,b : E_α^k-reactive hybridoma 2B4.11 using such membranes resulted in responses comparable to those found using antigen-presenting cells (APC); that is, similar amounts of IL-2 were produced at the same concentrations of antigenic peptides. Presentation of moth and pigeon cytochrome c peptides by E_β^b : E_α^k - or E_β^k : E_β^b-reconstituted membranes resulted in 2B4.11 response patterns similar to those previously described using B10.A or B10.A(5R) APC. These data conclusively demonsrates that differential stimulation by moth and pigeon cytochrome c peptides depends solely on structural differences in the E_β : E_α molecules used for antigen presentation.