Heterogeneity of Rabbit Homologous Skin Sensitizing Antibodies: IgE and a New Subclass IgG_a

Abstract

Homologous skin sensitizing antibodies in the rabbit can be differentiated by their requirement for complement in expressing the passive cutaneous anaphylactic reaction as complement dependent (CD) or complement independent (CI). CI antibodies are representative of the IgE class, while the CD antibodies belong to a proposed new subclass of IgG designated IgG_a (a = anaphylaxis). The following are characteristics of CI (IgE) antibodies: elution at 0.05 M on DEAE at pH 8.1, migration ahead of 7S in ultracentrifugation, molecular weight 215,000 daltons by Sephadex G-200, fast γ-electrophoretic mobility, isoelectric point, pI = 4.98 (5.68–4.58), 85–95% heat sensitivity, sensitivity to reduction plus alkylation and optimal sensitization period of 1–7 days. In contrast CD (IgG_a) antibodies show: elution at 0.01 M on DEAE, 7S in ultracentrifugation, MW 138,000 daltons, slow γ-electrophoretic mobility, pI = 6.90 (8.30–5.70), resistance to heating and to reduction plus alkylation and 1-day optimal SP. CI antibodies could be absorbed by anti-Fab, anti-ε, the homologous antigen and were not absorbed by anti-γ, anti-α, or heterologous antigens. The CD antibodies were absorbed by anti-Fab, anti-γ and not absorbed by anti-ε, anti-α, or heterologous antigens.

Isolation and Preparation of Antisera to Ovine IgE

“…In this study, heating to 56 °C had a dramatic effect on reaginic sheep serum. 90% of the PCA activity disappeared after 2-4 h. However, neat serum showed no reduction in PCA activity even after heating for 8 h. The reason for this is unclear but these results are similar to those obtained in rabbits [25,32]. Lindqvist [32], suggested a possible protective agent in reaginic sera; whereas Stux and Ovary [25] suggested that it may indicate a heat-stable subpopulation of IgE.…”

“…It has also been induced by immuni zation with alum-precipitated human gamma-globulin [19], Short-term skin-sensitizing IgG antibody has also been reported after immunization with DNP-HGG [20], Immunoglobulin G with passive cutaneous anaphylaxis (PCA) activity has been defined in man [21], mouse [22], rat [23], guinea pig [24] and rabbit [25]. The PCA activity of IgG antibodies is not affected by heat and it does not re main in the skin for more than 1-3 days, except in the case of the guinea pig and rabbit [26], In these species IgG can remain in the skin for a week [25,27],…”

Inflammatory mechanisms in the passive cutaneous anaphylactic reaction in the rabbit: evidence that novel mediators are involved

“…There was a heat-resistant component which is consistent with previous observations made with rabbit IgE (Revoltella & Ovary, 1969;Kravis & Zvaifler, 1974a;Stux & Ovary, 1976).…”

“…The likelihood that C5a was involved was small since the IgE antibody would not be expected to be complement fixing. Henson & Cochrane (1969) and Stux & Ovary (1976) both reported an anaphylactic IgG antibody in the rabbit which induced a PCA reaction that was dependent on an intact complement system. However, we could not find evidence for the existence of this antibody in our experiments.…”

“…In rabbits, IgE antibody can be raised by immunisation with a low dose (ptg quantities) of antigen mixed with aluminium hydroxide. This procedure produces maximum IgE titres after 120 days (Kravis & Zvaifler, 1974a) and a detailed study of the antibody was made by Stux & Ovary (1976). However, in this and other studies, no attempts were made to investigate which mediators were generated following antigen challenge, other than establishing that antihistamines were weak inhibitors.…”