An incomplete cold-reactive gamma G antibody with i specificity in infectious mononucleosis

Acute Liver Injury due to Severe Epstein-Barr Virus Infection

Epstein-Barr virus (EBV) is a widely dispersed herpesvirus, transferred through close personal contact between susceptible individuals and asymptomatic shedders of the virus. The liver is often affected, and involvement is usually subclinical and self-limited. However, immunocompromised patients and, more rarely, immunocompetent individuals can develop a severe and potentially fatal acute liver injury. To differentiate EBV hepatitis from other conditions, such as autoimmune hepatitis, lymphoproliferative disorders, and drug-induced liver injury, correlation with clinical history, laboratory findings, and histopathologic features is crucial. We report a unique case of a man who developed acute liver injury from a severe EBV infection.

The Clinical Pictures of Autoimmune Hemolytic Anemia

Autoimmune hemolytic anemia is characterized by shortened red blood cell survival and a positive Coombs test. The responsible autoantibodies may be either warm reactive or cold reactive. The rate of hemolysis and the severity of the anemia may vary from mild to severe and life-threatening. Diagnosis is made in the laboratory by the findings of anemia, reticulocytosis, a positive Coombs test, and specific serologic tests. The prognosis is generally good but renal failure and death sometimes occur, especially in cases mediated by drugs.

Autoimmune hemolytic anemia

Red blood cell (RBC) autoantibodies are a relatively uncommon cause of anemia. However, autoimmune hemolytic anemia (AIHA) must be considered in the differential diagnosis of hemolytic anemias, especially if the patient has a concomitant lymphoproliferative disorder, autoimmune disease, or viral or mycoplasmal infection. Classifications of AIHA include warm AIHA, cold agglutinin syndrome, paroxysmal cold hemoglobinuria, mixed-type AIHA, and drug-induced AIHA. Characteristics of the autoantibodies are responsible for the various clinical entities. As a result, diagnosis is based on the clinical presentation and a serologic work-up. For each classification of AIHA, this review discusses the demographics, etiology, clinical presentation, laboratory evaluation, and treatment options.

IVIG in the treatment of children with acute and chronic idiopathic thrombocytopenic purpura and the autoimmune cytopenias

IVIG has been shown to be useful in the treatment of acute and chronic ITP, immune neutropenia, and in some cases of AIHA. The mechanism of action of IVIG is owing to a number of factors, which include Fc blockade, immune modulation of T- and B-cell number and function, alterations in NK activity, and direct effects on autoantibody binding and production via the antiidiotypic antibody network. Current research efforts are directed toward elucidation of these modalities and determination of their relative importance in treating patients with immune-mediated cytopenias.

Autoantibodies against triosephosphate isomerase. A possible clue to pathogenesis of hemolytic anemia in infectious mononucleosis

In sera from patients with acute EBV, infection and the clinical symptoms of infectious mononucleosis antibodies of the Ig class M were found that are directed against two cellular proteins. The molecular mass of these proteins was determined to be 29 (p29) and 26 kD (p26), respectively, in SDS-PAGE. P29 was identified as part of the glycolytic enzyme triosephosphate isomerase (TPI) by comparison of the NH2-terminal amino acid sequences. A purified antibody against TPI induces a 51Cr release from human erythrocytes. Possibly, anti-TPI causes hemolysis, which is an infrequent but serious symptom of infectious mononucleosis.

Cold agglutination

Autoantibodies against red cells optimally reacting at 0 degree C, ie, CA, are normally found with low titers in the serum of human adults. High-titer CA may be induced by certain infectious agents, including M pneumoniae, EBV, CMV, and rubella virus, or may develop on the basis of chronic (malignant) B cell lymphoproliferation. The main clinical manifestation of cold agglutination is AIHA. Antigens and antibodies of cold agglutination are the best characterized reaction partners of a human autoimmune process. CA may recognize I and i antigens, which are lipid- and protein-linked branched and linear N-acetyl-lactosamine chains, respectively. They are precursors of the ABH blood group antigens and are converted into H by fucosylation. An alternative substitution by sialylation creates Gd, Fl, and probably Vo/Li antigens. CA with anti-Pr and anti-Sa specificities recognize 0-glycans with immunodominant sialyl groups on glycophorins. Several Pr subspecificities can be identified by chemically modified sialyl groups on glycophorins. Because CA in chronic lymphoproliferation are monoclonal antibodies, structure-specificity-interrelations of the antibodies could be identified by primary structure analyses of the N-terminal variable regions of H and L chains and by studies on CA idiotypes. Interrelations between distinct CA specificities and particular infectious agents could explain cold agglutination as a response to receptors for the agents or to the binding sites of antibodies against the agents. Interrelations also existing between certain CA isotypes (Ig classes and L chain types) and CA specificities could be a basis for the elucidation of the enigmatic etiology of chronic (malignant) monoclonal cold agglutination.

Comparative biochemical and genetic characterization of clonally related human B-cell lines secreting pathogenic anti-Pr2 cold agglutinins

To study the biology of cold autoimmune hemolytic anemia, Epstein-Barr virus (EBV)-transformed B-cell clones were established from a patient with splenic lymphoma associated with immune hemolysis due to an anti-Pr2 cold autoantibody. Studies were performed comparing the cold autoantibody present in culture supernatants of these cell lines to the pathogenic cold autoantibodies present in the patient's plasma. Cytogenetic studies of splenic lymphocytes demonstrated an abnormal karyotype (51XX, +3, +9, +12, +13, +18). After EBV transformation, eight clones secreting IgM, kappa anti-Pr were isolated; each clone had the same abnormal karyotype as above. DNA isolated from the clones and spleen was analyzed by Southern blot hybridization with JH, C mu, and C kappa probes; identical gene rearrangements were seen in each case. Anti-Pr antibodies, isolated from culture supernatant and serum were compared by isoelectric focusing (IEF) and demonstrated similar banding patterns. Distinctive binding patterns, however, were observed in 2/8 clones, suggesting structural differences. Adsorption studies with red blood cells further showed that the observed IEF banding patterns were solely due to anti-Pr cold autoantibody. With a thin-layer chromatography method, the biochemical determinants recognized by the cold autoantibodies were defined as glycolipids containing Neu Ac alpha 2-3Gal beta 1-4Glc sequences. The data demonstrate that the autoantibodies of the EBV-transformed B-cell lines were similar to the pathogenic monoclonal serum autoantibody in both structure and specificity. These clonal cell lines may thus serve to further study the biology of human B-cell lymphomas with defined autoantibody specificity.

Evans' syndrome as a presenting manifestation of atypical paroxysmal cold hemoglobinuria

Paroxysmal cold hemoglobinuria is a rare and potentially life-threatening acquired hemolytic anemia occurring either as an acute transient anemia following several different viral syndromes, or in a chronic idiopathic form. Episodic hemolysis in paroxysmal cold hemoglobinuria is usually associated with a biphasic (Donath-Landsteiner) IgG cold-reactive complement-fixing autohemolysin with anti-P specificity. Paroxysmal cold hemoglobinuria has not previously been associated with malignancy nor has it been clearly shown to be steroid-responsive. This report describes a patient with steroid-responsive autoimmune hemolytic anemia and immune thrombocytopenia (Evans' syndrome) associated with oat cell carcinoma of the lung and a unique biphasic anti-IgM autohemolysin. This case extends the spectrum of biphasic antibody-mediated immune cytopenias and widens both the clinical and the serologic definition of paroxysmal cold hemoglobinuria.

Haemolytic anaemia in previously healthy adult patients with CMV infections: report of two cases and an evaluation of subclinical haemolysis in CMV mononucleosis

Whereas haemolytic anaemia is commonly encountered in infants and young children with cytomegalovirus (CMV) infections, it is an infrequent complication of CMV-induced infections in previously healthy adults. The data from 2 such patients are presented. One patient's Hb fell to a level of 36 g/l, and she required prednisone and blood transfusions. Her direct antihuman globulin test (DAT) was positive (IgG), and her red blood cell survival (51Cr) revealed a T 1/2 of 5 d. Both saline-agglutinating and low-molecular-weight cold agglutinins (CA) (4 degrees C) that reacted against both cord and adult cells were identified. In the second case, a moderate haemolytic anaemia (lowest Hb 87 g/l) was accompanied by negative DAT and CA studies. 20 other patients with CMV-mononucleosis were evaluated for evidence of subclinical haemolysis. Reticulocyte counts greater than 3.0% were noted in 9 of these patients. Haptoglobin values were below 0.5 g/l in 13 patients, and a positive DAT was recorded in 3/10 cases. This study documents haemolysis in many non-immunosuppressed adult patients with CMV infections. The mechanism responsible remains obscure.

Autoimmune hemolytic anemia. 3. Cold antibody type

In cold autoimmune hemolytic anemia, the causative autoantibodies (cold agglutinins) are most reactive at low temperatures. The anti-I type of cold agglutinin is found in cold hemagglutination disease and in hemolytic anemia secondary to malignant lymphoma, leukemia, or atypical pneumonia. The anti-I type of cold agglutinin is found in many patients with infectious mononucleosis and in an occasional patient with other lymphoproliferative disorders. Paroxysmal cold hemoglobinuria, a disorder in which exposure to cold temperatures triggers massive hemolysis, is characterized by a unique biphasic cold autoantibody called the Donath-Landsteiner antibody. By way of summary and review of this and the two previous articles in this series, table 4 presents a practical approach to diagnosis of the autoimmune hemolytic anemias.

Lyme arthritis: correlation of serum and cryoglobulin IgM with activity, and serum IgG with remission

Forty-eight patients with erythema chronicum migrans (ECM) were studied prospectively for 6 to 18 months. Twenty-six patients had no later symptoms, but 22 subsequently developed Lyme arthritis and 9 of them also experienced neurologic abnormalities. Eighty-seven percent of patients with active ECM followed by subsequent involvement had cryoglobulins containing IgM compared to only 13% of those with active ECM and no later symptoms. The former group also had significantly lower IgG, C3 and C4 levels. Sixty-seven percent of patients still had serum cryoglobulins when neurologic disease was most active, and 45% had them when joint symptoms were most severe, but only 11% continued to have small amounts in remission. The number of patients who continued to have serum cryoglobulins with recurrent attacks of arthritis decreased with time. In contrast, patients always had cryoglobulins in joint fluid, a finding Lyme arthritis shares with rheumatoid arthritis. The cryoprecipitates from 2 of 10 patients contained particles with internal structure, but their viral nature is problematic. All components of antisera obtained from goats and rabbits immunized with cryoglobulins were absorbed by normal human sera. The amount of IgM in cryoglobulins correlated directly with serum IgM, which generally rose during exacerbations and fell during remissions; serum IgG and IgA moved conversely. Thus, IgM was an important correlate of clinical disease activity and IgG or remission.

Autoimmune haemolytic anaemia with the unusual combination of both IgM and IgG autoantibodies

Two patients with autoimmune haemolytic anaemia of no obvious aetiology are presented. Both cases had IgM autoantibodies which were cold agglutinins with anti-I specificity and were complement binding. Both cases also had IgG autoantibodies which were incomplete, of wide thermal range and also had anti-I specificity, but were not complement binding. The red cells of both patients were coated with C4/C3d and IgG.

Actual aspects of cold agglutination

Cold agglutinins (CA) can be directed against antigens of the I/i system and the Pr complex. In addition, anti-Gd CA have been recently described. The CA immunoglobulins, serological specificities and the antigen immunochemistry are reviewed. CA permitted studies on interrelations between antibody structures and specificities. The significance of subgroup preferences and cross-idiotypic specificities is discussed. Interrelations between CA specificities and certain virus infections are pointed out, and recent results obtained from studies using CA as indicators for membrane alterations of other than red cells are reviewed.

Immunofluorescence microphotometry for the detection of platelet antibodies. III. Demonstration of autoantibodies against platelets

After a survey of the literature dealing with the demonstration of platelet autoantibodies by immunofluorescence techniques, the results are given of a study in which immunofluorescence microphotometry was used for this purpose. The serum of 58, the platelets of 34, and the megakaryocytes of 2 patients with thrombocytopenia were investigated. In 21 of 52 sera (40%) in which the presence of platelet autoantibodies could be expected, positive results were obtained that could not be due to isoantibodies, either because the patients had not been pregnant and had not received blood transfusions or because the reactivity of the serum with the patient's own platelets was demonstrated. The platelets of 28 patients with thrombocytopenia not due to a platelet defect or decreased thrombopoiesis were investigated. In the platelets of 15 (54%) of these, significant differences in fluorescence were found with anti-immunoglobulin conjugate as well as with anti-IgG, -IgA, -IgM, or -complement reagents. It was concluded that in these patients in vivo sensitization of the platelets with autoantibody was demonstrated. In two patients an indication of the in vivo sensitization of the megakaryocytes was also obtained.

Hemolytic anemia associated with multiple autoantibodies and low serum complement

A 37 year old woman with extravascular hemolytic anemia had a positive Monospot test associated with positive antiglobulin and anticomplement Coombs' tests, cold agglutinins and warm autoantibodies. IgG-kappa (k) antibodies, which reacted with all panel red cells at 37 degrees C, were eluted from her circulating red cells. However, neither immunoglobulins nor C3 was detected after her serum was adsorbed with heterologous red cell stroma at 37 degrees C and eluted at the same temperature in glycine buffer. In contrast, IgM-kappa and IgM-lambda (lambda), IgG-3-kappa, IgG4-lambda, IgA-lambda and C3 were eluted at 37 degrees C from heterologous red cell stroma after adsorption with her serum at 0 degrees C. Thus, antibodies of several types, which were present in the patient's serum, reacted optimally with red cell antigens at low temperature. Cold-reactive IgG3-kappa antibodies, which also capable of interacting with red cells at 37 degrees C, probably accounted for the IgG-kappa antibodies eluted from the patient's circulating red cells. The patient's serum C4 titers were decreased, with low normal to moderately depressed C3 and low normal C5, indicating that the anti-red cell IgM and/or IgG3-kappa antibodies probably fixed complement. A localized cold stress test resulted in a transient increase in plasma hemoglobin and a decrease in serum C3 titer. These findings, and the beneficial clinical response obtained with small doses of prednisone, suggest that both the cold-reactive antibodies and the IgG-kappa on circulating red cells were pathophysiologically significant. This is the first report of a patient with multiple red cell autoantibodies in whom serum complement component titers were determined in conjunction with characterization of the anti-red cell immunoglobulins. Subclinical infectious mononucleosis may have preceded the prolonged hemolytic episode. Clinical evidence of systemic lupus erythematosus has not appeared.

Light chain sequences of human IgM cold agglutinins (variable-region subgroups amino-acid sequence-kappa light chain-N-terminal)

The amino-terminal amino-acid sequence has been determined for the kappa light chains of nine IgM cold agglutinins with specificity for blood group-related carbohydrate antigens. Six of the nine sequences corresponded to the prototype VK(III) subgroup pattern, two to that of subgroup VK(II), and only one to the VK(I) subgroup. This distribution of kappa subgroups differs markedly from that of normal and myeloma proteins sequenced to date, where the VK(I) subgroup is more prevalent than either VK(II) or VK(III). Evidence is presented that supports the conclusion that the unusual subgroup distribution relates to the antibody property itself and not to some other attribute of these molecules.