The immune response to pneumococcal polysaccharide type III is followed by increased production of an antibody antifactor

Purification of an IgM antibody response-enhancing factor to the alpha 1-6 epitope of native dextran from serum and supernatants from T-cell hybridomas

We have found that some hybrids produced by fusing AKR thymoma BW 5147 with spleen cells from Dx-hyperimmunized CBA mice produce factors that affect the primary CBA IgM PFC response. By the use of HPLC-DEAE chromatography, sometimes combined with affinity chromatography, we have purified from hyperimmune anti-Dx serum, from ascites-growing T hybrids, and from normal CBA serum a family of factors that specifically enhance the anti-Dx IgM response. They show specificity for either Dx or anti-Dx, they may contain an Iak determinant, and they are genetically restricted in their function. The factors from all three sources are found in the same fractions after separation and move in fractions without Ig contamination. The affinity-purified factor was eluted at an NaCl concentration of 0.15-0.20 M. On the basis of these characteristics we believe that we have separated a class of T cell-derived helper factors from serum. The concentration of the factor in serum increases after hyperimmunization with Dx. As a specificity control we show that the same sera contain a natural anti-SRBC IgM response-enhancing factor. It co-separates with the anti-Dx-enhancing factor, but they can be distinguished by their preferential binding to their own antigens.