CELL-SURFACE IMMUNOGLOBULIN OF HAMSTER LYMPHOID-CELLS

Cell surface immunoglobulin (Ig) of hamster lymph node cells was analyzed utilizing lactoperoxidase catalyzed radioiodination, lentil leclin affinity chromatography, immunoprecipitation, and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Immunoprecipitation of the radiolabeled cell surface Ig with a polyvalent rabbit anti-hamster Ig antiserum yielded 3 peaks of radioactivity when unreduced samples were analyzed by SDS-PAGE: a major Ig peak (I) at 220,000 daltons and two minor peaks, one (II) at 170,000 daltons and another (III) at 110,000 daltons. Upon reduction peak I yielded heavy chains with mobilities similar to mouse cell-surface μ (84,000 daltons) and light chains: peak II yielded heavy chains of 68,000 daltons and light chains; peak III yielded the same size heavy chains as peak I plus light chains and thus represents Ig half molecules (H-L). A maximum of 40% of peaks I and III were precipitated by a cross-reactive rabbit anti-mouse μ antiserum. The 68,000 dalton heavy chain has some of the characteristics of mouse δ chain (apparent mol. wt and susceptibility to papain), however, it is not precipitated by an anti-mouse δ antiserum and represents only 20% of the total heavy chains in 1-6-month old hamsters. The same results were obtained with radioiodinated hamster spleen cell lysates. These results indicate that hamster cell surface Ig consists of monomeric IgM and one (or two) other isotype(s). Either a sub-population of the 220,000 dalton Ig (H = 84,000), or the 170,000 dalton Ig (H = 68,000) may be the hamster IgD equivalent. © 1979.