Immunoglobulin double isotype-producing hybridomas isolated from an autoimmune (NZB x NZW)F1 mouse.
In the sera of (NZB x NZW)F1 (B/W) mice that develop a lupus-like syndrome, increased levels of IgG antibodies (Ab) reacting with TNP have been detected before the appearance of IgG anti-DNA Ab and clinical symptoms. A single injection of trinitrophenyl-bovine serum albumin (TNP/BSA) in physiological saline into a young B/W mouse (3 months old), followed by fusion of its splenocytes 3 days later, gave rise to hybridomas simultaneously secreting IgM and IgG Ab with anti-TNP reactivity. Both mu and gamma chains were detected in culture supernatants by ELISA, and double isotype-producing cells were labeled by immunofluorescence. Molecular analysis of two of these double isotype-producing hybridomas showed the presence of mRNA coding for both mu and gamma chains of Ig, and this gamma mRNA could be translated in vitro into a gamma heavy (H) chain. Comparison of the H chain variable-region sequences of IgM and IgG revealed 100% homology between mu and gamma V(H) genes in one clone, while mu and gamma V(H) genes showed only 80% homology in the other clone. Both clones produced a single kappa light (L) chain. These two hybridomas, isolated from a B/W mouse, thus represent two different mechanisms of double isotype expression: the first one corresponds to an IgM to IgG switch, while the second one reflects a lack of allelic exclusion.
Payelle-Brogard
B
B
Unité d'Immunocytochimie, CNRS URA 1961, Département d'Immunologie, Institut Pasteur, Paris, France.
Ragimbeau
J
J
Avrameas
S
S
Christodoulou
C
C
D000483:Alleles; D000595:Amino Acid Sequence; D000818:Animals; D000918:Antibody Specificity; D001323:Autoantibodies / Q000235:genetics / Q000276:immunology*; D001483:Base Sequence; D004797:Enzyme-Linked Immunosorbent Assay; D017578:Immunoglobulin Class Switching; D007074:Immunoglobulin G / Q000235:genetics / Q000276:immunology*; D007132:Immunoglobulin Isotypes / Q000276:immunology*; D007075:Immunoglobulin M / Q000235:genetics / Q000276:immunology*; D051379:Mice; D008969:Molecular Sequence Data
D001323:Autoantibodies; D007074:Immunoglobulin G; D007132:Immunoglobulin Isotypes; D007075:Immunoglobulin M