» Anti-Human Globulin Serum conforms to the regulations of the FDA concerning biologics (see Biologics 1041). It is a sterile, liquid preparation of serum produced by immunizing lower animals such as rabbits or goats with human serum or plasma, or with selected human plasma proteins. It is free from agglutinins and from hemolysins to nonsensitized human red cells of all blood groups. It contains a suitable antimicrobial preservative. Three varieties of Anti-Human Globulin Serum are recognized: (1) a general-purpose polyspecific reagent which, as a minimum, contains antibodies specific for immunoglobulin IgG, and at least the C3d component of human complement (for use in the direct antiglobulin test, it contains this Anti-C3d and Anti-IgG activity) and which may be artificially colored green; (2) a reagent containing antibodies only against immunoglobulin IgG (not heavy chain specific) intended for use in the indirect antiglobulin test, and which may be artificially colored green; and (3) reagents containing antibodies specific for individual or selected components of human complement, such as Anti-C3, and Anti-C3b-C3d-C4, or a single class of immunoglobulins, such as Anti-IgG (heavy chain specific), used only to identify plasma components coated on the surface of red blood cells. Anti-Human Globulin Serums containing Anti-IgG meet the requirements of the test for potency, in parallel with the U.S. Reference Anti-Human Globulin (Anti-IgG) Serum (at a 1:4 dilution) when tested with red cells suspended in isotonic saline sensitized with decreasing amounts of nonagglutinating Anti-D (Anti-Rho) serum, and with cells sensitized in the same manner with an immunoglobulin IgG Anti-Fya serum of similar potency. Anti-Human Globulin Serum containing one or more Anti-complement components meets the requirements of the tests for potency in giving a 2+ agglutination reaction (i.e., agglutinated cells dislodged into many small clumps of equal size) by the low-ionic sucrose or sucrose–trypsin procedures when tested as recommended in the labeling. Anti-Human Globulin Serum containing Anti-3Cd activity meets the requirements for stability, by potency testing of representative lots every 3 months during the dating period.