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

Abstract

Extract

Auto-immune, haemolytic anacmias (AHA) of man (Dacie, 1963) and domestiicated animals (Schalm, 1965; Farrelly et al., 1966; Lapras and Oudar, 1971) are classified either as idiopathic or secondary to an underlying disease process (Pirofsky, 1969). 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) while low titres of cold antibodies occur in most normal sera (Finland et al., 1945; Ellenhorn and Weiner, 1953). A similar situation occurs in animals (Wheeler, 1938). The normal cold antibodies act over a restricted temperature range and seldom agglutinate erythrocytes above 10 to 15 ° C (Pirofsky, 1969). 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) and may overlap low physiological temperatures (Barcroft and Edholm, 1946).