Infectious mononucleosis: immunoglobulin synthesis by cell lines.

Immunoglobulin synthesis by 16 long-term suspension cultures of mononuclear cells derived from peripheral blood of nine patients with heterophile-positive infectious mononucleosis (IM) has been demonstrated by radioimmunoelectrophoretic techniques. All cell lines synthesized molecules with IgG (gamma) heavy chain specificity. 14 cell lines produced molecules with IgM (mu) heavy chain specificity and 11 cell lines produced molecules with IgA (alpha) heavy chain specificity. No detectable synthesis of molecules with IgD (delta) heavy chain specificity was observed by these cell lines derived from peripheral blood of patients with IM. 13 cell lines produced molecules with type K (kappa) light chain specificity and 6 cell lines produced molecules with type L (lambda) light chain specificity. Of interest, 9 of 16 lines produced IgG (gamma), IgA (alpha), and IgM (mu) heavy chain molecules and 5 of these cell lines produced molecules with type K (kappa) and type L (lambda) light chain specificity as well. Further characterization by combined polyacrylamide gel filtration, immunodiffusion, and radioautography indicated the presence of newly synthesized immunoglobulin molecules with both heavy and light polypeptide chains in close association as well as free light polypeptide chain synthesis. Investigation of the localization of immunoglobulin in single cells by immunofluorescent techniques revealed that 5-22% of cells in these lines were strongly reactive with a fluorescein isothiocyanate-conjugated rabbit antisera directed against the antigenic determinants of human IgG and cross-reactive with the determinants common to IgA and IgM. No heterophile antibody, heteroagglutinin, or hemolytic antibody could be demonstrated in these cell lines derived from peripheral blood of patients with heterophile-positive infectious mononucleosis.