Immunology. Named after Robin Coombs, born 1921. An immunological laboratory test to detect incomplete antibodies coating erythrocytes. In the direct Coombs test, red blood cells, taken directly from a sensitized individual, are agglutinated by antigammaglobulin antibodies (e.g., in haemolytic disease of newborn and autoimmune haemolytic anaemia). In the indirect Coombs test, a patients serum is incubated with test red blood cells to detect circulating antibodies.