A cold agglutinin: Om

Anti-j: human cold agglutinins recognizing linear (i) and branched (I) type 2 chains

Two IgM lambda cold agglutinins (CAs) reacted with protease- and sialidase-resistant antigens expressed in equal strength on human adult (I), newborn (i), i adult, rabbit (I) and rhesus monkey (i) erythrocytes. The antibodies were inhibited by the linear type 2 sequence lacto-N-neotetraose and the branched type 2 sequence lacto-N-neohexaose. Endo-beta-galactosidase treatment of red cells, which splits type 2 chains from the surface, abolished CA reactivity. The CAs expressed the idiotype recognized by the anti-idiotype 9G4 specific for anti-I and anti-i CAs. The data suggest that the two CAs recognize linear (i) as well as branched (I) type 2 chains. It is proposed to term these CAs anti-j.

Characterization of autoantibodies in mixed-type autoimmune hemolytic anemia

Three of 46 patients with autoimmune hemolytic anemia (AIHA) satisfied the diagnostic criteria for mixed-type AIHA in which both warm-type and cold-type autoantibodies against red blood cells (RBCs) are present. The specificities of these autoantibodies were analyzed. All of the warm-type autoantibodies were IgG-chi, and the specificities were not serologically classified. The autoantibody of patient 1 reacted to the 41- and 80-kD peptides on immunoblotting, and the epitope corresponding to it was papain sensitive. Two warm-type autoantibodies from patients 2 and 3 resembled each other in serological analyses and reacted with a protease- and neuraminidase-resistant antigen. However, the antigen corresponding to the autoantibody of patient 3 was located on the 37-kD peptide by immunoprecipitation. All of the cold-type autoantibodies were IgM-cha and showed high titer and high thermal amplitude. According to the reaction pattern with untreated and enzyme-treated RBCs, the cold-type autoantibodies of patients 2 and 3 were revealed to be anti-Om and anti-I, respectively. In patient 1, the cold-type autoantibody was characterized as having high affinity for autologous RBCs, but its specificity was unclassified. The antigens corresponding to the cold-type autoantibodies were not located by immunoblotting and immunoprecipitation. These serological and immunochemical approaches to autoantibodies in mixed-type AIHA revealed that the warm and cold components recognized the different antigens.

[Two-dimensional electrophoretic study of monoclonal gammopathies and cold agglutinins associated with a chronic hemolytic anemia]

Two-dimensional gel electrophoresis (2-DGE) associated with a very sensitive silver staining is one of the most powerful technique available for protein analysis. Proteins are separated in the first dimension by isoelectric focusing in a pH gradient, and in the second dimension by polyacrylamide gel electrophoresis. Proteins are thus separated according to their charge and to their size. The high resolution of 2-DGE allows the analysis of complex mixture of proteins with a great reproducibility. More than hundred different proteins can be individualized after 2-DGE of plasma or serum samples. Using this technique, we analysed samples obtained from normal donors and from patients with different gammopathies. Our results confirm that the heavy chains of immunoglobulins are easily detected and that the alpha, gamma and mu chains are clearly differentiated from one another. The typical polyclonal heavy and light chains appear as indiscrete spots after staining of the gels. On the contrary, the monoclonal chains appear as discrete spots. Monoclonal heavy chains have a restricted charge heterogeneity. We also analysed cold agglutinins, partially purified from plasma of three patients showing evidence of chronic hemolysis, a positive direct antiglobulin test of the complement type and anti-I autoantibodies. The 2-DGE have clearly demonstrated that these cold agglutinins were monoclonal IgM, when these later were not detectable by immunofixation electrophoresis. We think that the 2-DGE is a very usefull specialized aid to the analysis of such particular immunohematological problems.