Studies on the Conformation of Purified Human and Canine γA-Globulins and Equine γT-Globulin by Optical Rotatory Dispersion

Report of the Second Equine Leucocyte Antigen Workshop, Squaw valley, California, July 1995

The final assignment of antibody clusters for leucocyte antigens and immunoglobulins, as described in detail in Sections 3 and 4, is summarized in Table 4. Together with other mAbs developed outside of ELAW II (Table 9) this pool of reagents represent a powerful array of tools for the study of equine immunity. The Second Equine Leucocyte Antigen Workshop made considerable advances in pursuing the objectives of establishing the specificities of mAbs and achieving consensus on the nomenclature for equine leucocyte and immunoglobulin molecules. Of equal importance, several productive collaborations were fostered among the participating laboratories and observers. Overall, enormous advances have been made in the past decade since mAbs specific for equine leucocyte antigens and immunoglobulins were first reported. There remains enormous scope and need for further studies of equine leucocyte antigens and immunoglobulins, both for the purposes of comparative immunology and for the good of the horse. In the future novel techniques will be required to develop reagents for specific target antigens such as the orthologues of the CD25 or CD45 isoforms. In studies of equine immunoglobulins the functional role of the IgG isotypes must be better established, reagents for IgE must be developed, and cloning of the immunoglobulin heavy chain genes will be essential if the complexities of the IgG sub-isotypes are to be elucidated. The tasks still facing the currently small group of equine immunologists throughout the world remain formidable, and will only be tackled successfully in a spirit of collaboration.

Investigation of the antigenic relationship between equine IgG and IgGT

The antigenic cross reactivity between equine IgG and IgGT was investigated. On the basis of immunodiffusion and immunoelectrophoresis reactions using an antiserum raised against the Fc fraction of IgGT, this equine immunoglobulin can be unequivocally classified as a subclass of IgG.

Isoelectric focusing of IgA and IgM in composite acrylamide-agarose gels

A convenient method for isoelectric focusing of intact polymeric IgA and IgM is described. This technique employed composite gels containing 1.0% acrylamide and 0.75% agarose which exhibited minimal electroendosmotic properties. The spectrotypes obtained with mouse IgA myeloma proteins, a human IgA myeloma and rabbit secretory IgA preparations were compared in three gel systems: 5% acrylamide, 0.8% agarose and the composite gel. With respect to resolution of component bands, the composite gel was superior to the other two systems. Hapten binding studies with MOPC-315 IgA and a rabbit secretory IgA anti-DNP antibody indicated that the focused IgA molecules retained their binding site integrity in the composite gel. The pI ranges obtained with microscale sucrose isoelectric focusing and composite gel system showed good correspondence, with the latter exhibiting enhanced resolution. Studies with MOPC-104E IgM revealed improved resolution in the composite gel when compared to the agarose system. Comparison of pI ranges for IgA and IgM immunoglobulins obtained in the present study with those reported previously suggest that IgA spectrotypes are confined to an acidic pI range (3.4--6.4), whereas IgM spectrotypes are not (4.3--8.8).