Abstract
Examination of the subclass distribution of murine antibodies directed against groups A and C streptococcal carbohydrate, α-(1→3) dextran and phosphocholine yields the surprising observation that these carbohydrate antigens stimulate IgG responses largely restricted to the rare IgG3 subclass. This subclass restriction is particularly impressive in light of the low circulating levels of IgG3 in nonimmune mouse serum and the failure of a variety of other antigens including proteins and aromatic haptens to stimulate IgG3 antibody production. Attempts to alter the subclass restriction of antibodies with carbohydrate specificity by immunization with carbohydrate-coupled protein have been unsuccessful and indicate that immunoregulation of subclass expression probably occurs at the level of the antibody forming (B) cell. It is therefore conceivable that VH regions of murine immunoglobulins may be restricted to particular IgG subclasses. A similar type of subclass restriction has been reported in human and rat anti-carbohydrate antibodies. This recruitment of a minor immunoglobulin isotype by carbohydrate antigens in several species further supports the concept of immunoregulation at the level of subclass, and suggests that these and other mammals may share a structurally similar isotype with perhaps a common evolutionary origin.
Footnotes
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↵2 Supported by the Medical Scientist Training Program Grant GM-02016.
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↵3 Supported by United States Public Health Service Fellowship AI-05344.
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↵4 Supported by United States Public Health Service Training Program Grant H1-07081.
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↵5 Supported by United States Public Health Service Fellowship AI-05558.
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↵1 This work was supported by United States Public Health Service Grant A1-11635 and by National Science Foundation Grant PCM76-09719.
- Received March 23, 1978.
- Accepted May 2, 1978.
- Copyright © 1978 by The American Association of Immunologists, Inc.
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