An anaemic state in a horse associated with a cold-acting antibody

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Abstract
Extract Auto-immune, haemolytic anacmias (AHA) of man (Dacie, 1963 Dacie, J. V. 1963. The Haemolytic Anaemias; Congenital and Acquired. Part II. The Auto-immune Haemolytic Anaemias, London: Churchill. [Google Scholar] ) and domestiicated animals (Schalm, 1965 Schalm, O. W. 1965. Veterinary Hematology, 2nd ed., Philadelphia: Lea and Febiger. [Google Scholar] ; Farrelly et al., 1966 Farrelly, B. T. , Collins, J. D. and Collins, S. M. 1966. Autoimmune haemolytic anaemia (AHA) in the horse. Irish vet. J., 20: 42–45. [Google Scholar] ; Lapras and Oudar, 1971 Lapras, M. and Oudar, J. 1971. “Autoimmune diseases of animals: the present state of knowledge”. In Veterinary Medical Review, Vol. 2/3, 248–287. Leverkusen, , Germany: Farbenfabriken Bayer AG. [Google Scholar] ) are classified either as idiopathic or secondary to an underlying disease process (Pirofsky, 1969 Pirofsky, B. 1969. Autoimmunization and the Autoimmune Haemolytic Anemias, Baltimore: Williams & Wilkins. [Google Scholar] ). In both categories antibodies active against the indivual's own erythrocytes are formed. These auto-antibodies are of two types being either warm or cold-acting. Warm-acting antibodies are most effective at 37°C, belong to the IgG class of immunoglobulins, and are incomplete in that, generally, they do not cause autohaemagglutination. Coldacting, or cryopathic, antibodies show maximum activitv at 4°C, are of the IgM immunoglobulin class and are capable of effecting autohaemagglutination. The two types of antibodies also differ in their prevalence. In man warm-acting antibodies occur infrequently and are always pathological (Dacie, 1963 Dacie, J. V. 1963. The Haemolytic Anaemias; Congenital and Acquired. Part II. The Auto-immune Haemolytic Anaemias, London: Churchill. [Google Scholar] ) while low titres of cold antibodies occur in most normal sera (Finland et al., 1945 Finland, M. , Samper, B. A. and Barnes, M. W. 1945. Cold agglutinins. IV. Critical analysis of certain aspects of a method for determining cold isohemagglutinins. J. clin. Invest., 24: 483–490. [Google Scholar] ; Ellenhorn and Weiner, 1953 Ellenhorn, M. J. and Weiner, D. 1953. Variables in the determination of cold hemagglutinins. Am. J. clin. Path., 23: 1031–1039. [Google Scholar] ). A similar situation occurs in animals (Wheeler, 1938 Wheeler, K. M. 1938. Group specific agglutinins in rabbit serum for human cells; cold agglutinins. J. Immunol., 34: 409–417. [Google Scholar] ). The normal cold antibodies act over a restricted temperature range and seldom agglutinate erythrocytes above 10 to 15 ° C (Pirofsky, 1969 Pirofsky, B. 1969. Autoimmunization and the Autoimmune Haemolytic Anemias, Baltimore: Williams & Wilkins. [Google Scholar] ). Clinically important cold antibodies differ from normal cold antibodies in two respects. First, the titres of such antibodies are much higher, and, secondly, while being most effective at 4°C, their range of thermal activity is extended (Evans et al., 1965 Evans, R. S. , Turner, E. and Bingham, M. 1965. Studies with radioiodinated cold agglutinins of ten patients. Am. J. Med., 38: 378–395. [Google Scholar] ) and may overlap low physiological temperatures (Barcroft and Edholm, 1946 Barcroft, H. and Edholm, O. G. 1946. Temperature and blood flow in the human forearm. J. Physiol., 140: 366–376. [Google Scholar] ).