Influence of the valency and hydrophobicity of an antigen on its efficiency of processing and presentation by antigen-specific B cells.

We examined the influence of antigen structure on the efficiency of antigen-specific B-cell processing and presentation. The ability of untransfected and anti-TNP surface IgM (sIgM) bearing transfected TA3 B-hybridoma cells to process and present various conjugates of 2,4,6-trinitrophenyl-pork insulin (TNP-PI) to PI/I-Ad-specific T cells was investigated. Similar antigen concentrations were required for presentation of underivatized antigen by untransfected and transfected cells (antigen-non-specific presentation). Transfected cells present TNP-PI at about a 50-fold lower concentration and TNP-ovalbumin (TNP-OVA), at a 600-fold lower concentration than do untransfected cells (antigen-specific presentation). PI was derivatized at 3 possible residues, A1, B1 and B29, and the different TNP-PI conjugates obtained were separated by hydrophobic interaction high-pressure liquid chromatography. All TNP1-PI conjugates were presented equally by transfected and untransfected cells. Transfected TA3 cells presented a TNP2-PI conjugate derivatized at A1 and B29, TNP2(A1,B29)-PI, at about a 50-fold lower concentration than was required by untrasfected cells. Another TNP2-PI conjugate, derivatized at residues A1 and B1, TNP2(A1,B1)-PI, and a TNP3(A1,B1,B29)-PI conjugate were presented at about the same concentration by transfected vs untransfected B cells. Of the various TNP conjugates tested, only TNP2(A1,B29)-PI, which is more hydrophobic than any of the other TNP-PI conjugates, was processed more efficiently by transfected anti-TNP-specific TA3 cells vs untransfected cells. The efficiency of presentation of these TNP-PI conjugates was directly proportional to their rate of processing. Our data demonstrate that the valency and relative hydrophobicity of an antigen control its binding to sIgM and the efficiency of processing and presentation by B cells.