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

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. [Crossref], [PubMed] , [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. [Crossref], [PubMed] , [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. [Crossref], [PubMed] , [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. [Crossref] , [Google Scholar]).