anti-I Specificity Research Articles

Fatal, Rapidly Progressive EBV-Associated Warm Autoantibody Hemolytic Anemia (WAIHA): A Rare Case Study

Abstract Introduction/Objective Separately WAIHA and Epstein-Barr Virus-infectious mononucleosis (EBV-IM) are well- studied clinical entities. EBV-IM cases are commonly linked with cold autoagglutinins (IgMs with anti-i specificity), but uncommonly associated with WAIHA. More rarely, EBV-IM can be associated with rapidly fatal AIHA. Prompt and appropriate diagnostic Blood Bank testing for WAIHA in EBV-infected patients should include work-ups to prevent missing the possibility of treating complicating WAIHA. Methods/Case Report A 24-year-old woman presented to the ED with a month of cough/cold symptoms, night sweats, cervical lymphadenopathy, and imaging showing diffuse thoracic lymphadenopathy. DNA/PCR testing was positive for active EBV infection and a lymph node biopsy was diagnostic for EBV lymphadenitis. Increasing respiratory distress developed, coupled with renal and liver insufficiency, hypotension, and possible DIC, and (suspected septic) shock. On hospital day (HD) 5, altered mental status worsened, cardiac arrest occurred requiring resuscitation and vasopressors, and acidosis trended rapidly higher. The patient rapidly decompensated and she was compassionately extubated, expiring on HD 6. There were significant laboratory interval changes in the final 20 hours of life. New positive DATs (with anti-IgG and - C3b/d), a pan-reactive warm autoantibody of broad specificity (in plasma & eluate), onset of acute hemolysis (nadir Hgb to 4.6 g/dL with net drop of 4.7 g/dL & LDH 23, 582 U/L), coagulopathy (peak PT 96.6 sec) and evidnece of organ failure. Blood Bank testing, received on HD 5 at 21:45, was resulted in the EMR on HD 6 at 00:30 and the patient expired at 05:15--further illustrating the rapid clinical course presented in this case. Results (if a Case Study enter NA) N/A Conclusion This patient died of complications directly associated with acute, immune-mediated intravascular hemolysis leading to high-output cardiac failure and resulting in multi-organ failure. With a relative paucity of published EBV-IM WAIHA associations, the rapidly evolving unexpected hematologic sequelae observed complicated the clinical recognition and treatment of severe WAIHA during the course of treatment for clinically suspected DIC. The rapid progression of this patients’ symptoms and laboratory values did not allow for adequate recognition of WAIHA-related pathogenesis and appropriate interventions.

EBV-related Cold Agglutinin Disease Presenting With Conjugated Hyperbilirubinemia: A Pediatric Case Report and Mini Review

Hemolytic anemia occurs in only 1% to 3% of hospitalized patients with infectious mononucleosis. The authors describe an 8-year-old girl without cervical lymphadenopathy or splenomegaly, who presented with conjugated hyperbilirubinemia and was diagnosed with cold agglutinin disease caused by an immunoglobulin M autoantibody with anti-i specificity. Acute Epstein-Barr virus infection was confirmed by serologic and molecular methods. She recovered uneventfully after a 3-week course of methylprednisolone. Epstein-Barr virus infection should be considered in any case of hemolytic anemia associated with hepatic dysfunction, especially when direct antiglobulin test is positive for C3d. In these cases, a course of corticosteroids seems safe and may be beneficial.

Severe hemolytic crisis due to cold agglutinins associated with Mycoplasma pneumoniae infection that complicated the compatibility tests

The cold agglutinins (CAs) associated with Mycoplasma infection may give rise to autoimmune hemolytic anemia (AIHA), and in rare cases, results in severe crises requiring hospitalization. The present case was this kind with severe hemolytic crises due to clinically significant CA that had caused the life-threatening AIHA in association with the infection by Mycoplasma pneumoniae. The blood specimens were collected in the warm environment to obviate spontaneous autoagglutination. Autoimmune nature of the CA involved was established by the direct antiglobulin test (DAT) using reagents obtained from commercial sources. The serological specificity of the CA was ascertained by titration by saline tube test against the red blood cells (RBCs) from the adults and the newborn infants as well as the hemagglutination inhibition study using human milk as a source of the soluble I antigen. The patient's clinical and other details were obtained from the hospital records. A 20-year-old male admitted to the hospital with a severe hemolytic crisis that required blood transfusion. DAT on his RBCs was positive due to the presence of C3d complement fraction, in concurrence with a high-titer CAs with anti-I specificity and positive serological test for M. pneumoniae. A severe hemolytic crisis was evident by sudden drop in hemoglobin, presence of reticulocytes and erythroblasts in circulation. The patient was conservatively treated with antibiotics, steroid, and blood transfusions with improvement in condition and was discharged after 7 days of hospitalization. He was followed up for the next 3 months through which he continued to be in good condition. The investigations showed a rare case of the CA, with anti-I specificity, causing severe hemolytic crisis in association with M. pneumoniae infection that required hospitalization.

Clinical and Serological Characteristics of Cold Autoimmune Hemolytic Anemia with Concomitant Cold Agglutinin and Donath-Landsteiner Antibodies

BackgroundThe two major types of cold autoimmune hemolytic anemias are cold agglutinin disease (CAD) and paroxysmal cold hemoglobinuria (PCH). In CAD, the cold agglutinin is usually IgM with anti-I specificity. In PCH, the Donath-Landsteiner (DL) antibody is a cold reacting IgG with anti-P specificity. In this study, we describe the clinical and serological characteristics of patients with autoimmune hemolytic anemia positive for both cold agglutinin and DL antibodies.MethodsOn review of our immunohematology reference laboratory database, we identified patients over a 16-year period (January 2000- March 2016) with the following: i) age ≥18 years, ii) hemoglobin (Hb) <12g/dL, iii) positive direct antiglobulin test (DAT) with hemolysis (increased lactate dehydrogenase/low serum haptoglobin/ elevated indirect bilirubin), and iv) tested for both CAD and DL antibodies. We classified the patients into 3 cohorts. Cohort 1 included patients positive for both cold agglutinin (titer ≥1:64) and DL antibodies. Cohort 2 consisted of patients with DL antibody but no cold agglutinin (titer <1:64), while Cohort 3 was comprised of patients with cold agglutinin but no DL antibody. We evaluated the clinical response based on the GIMEMA (Gruppo Italiano Malattie EMatologiche dell'Adulto) criteria (Barcellini W, et al . Blood 2014) defined as i) complete (CR): hemoglobin ≥12 g/dL with normalization of at least one previously abnormal hemolytic marker; ii) partial (PR): hemoglobin 10-12 g/dL with hemolysis; or iii) none (NR): if any of the above criteria were not met.ResultsSeven patients had cold autoimmune hemolytic anemia with concomitant cold agglutinin and DL antibodies (Cohort 1). The clinical and serological characteristics are described in table 1. The median age at diagnosis was 68 years (range: 59-78) and the median hemoglobin at onset was 10.3 g/dL (range: 8.2-10.6). Six had red cell agglutination in the blood smear. Two patients had a recent history of infection (1 with Mycoplasma pneumoniae and 1 with upper respiratory tract infection). The median follow-up was 4.8 months (range: 1.0-166.4). Five patients received steroid/other immunosuppressants and two were managed conservatively. The clinical response to treatment was CR in 28.6% patients, PR in 42.9%, and NR in 14.3%. In comparison, Cohort 2 had a 20% CR, 20% PR and 40% NR, while Cohort 3 had a 50% CR, 25% PR and 25% NR, respectively.ConclusionOur study is the first series describing patients with cold autoimmune hemolytic anemia with concomitant cold agglutinin and DL antibodies. In terms of clinical response, patients with negative DL antibodies and cold agglutinin titers >1:64 had better response (50% CR, Cohort 3) to immunosuppressants compared to patients with positive DL antibody (20-30% CR, Cohorts 1 and 2). Large scale studies may be warranted to determine the treatment strategies among patients with concomitant DL and high cold agglutinin titers. [Display omitted] DisclosuresKay:Agios: Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Research Funding; Tolero Corporation: Research Funding; Gilead: Research Funding. Winters:Fresenius Kabi USA: Consultancy; Eliaz Therapeutics Inc: Membership on an entity's Board of Directors or advisory committees; Sanofi Inc: Other: Moderated opinion leader's forum; Wiley Blackwell: Employment; Regional Health Inc: Consultancy; Mayo Clinic: Employment; Grifols International SA: Consultancy.

Extensive cutaneous necrosis in a 12-year-old girl: an unusual complication of secondary cold agglutinin syndrome.

Cold agglutinin syndrome (CAS) secondary to infection is rare, usually presenting with anaemia and minor skin changes. A 12-year-old girl with secondary CAS associated with extensive cutaneous necrosis is reported. She presented with fever and multiple necrotic lesions over both cheeks, the tip of nose, ear margins, hands and buttocks, along with pallor, hepatospenomegaly, acrocyanosis and gangrene of the fifth digit of the right hand. She had anaemia, unconjugated hyperbilirubinaemia and a positive direct antiglobulin test owing to cold agglutinins of the IgM type with anti-i specificity and titres of 1:512 at 4°C. Results of bone marrow examination were normal and cryoglobulins were negative. Cold antibodies released even during a brief, self-limited febrile illness can cause widespread cutaneous gangrene. We believe this is the first report in the paediatric age group.

Immunoregulatory role for a public IgM idiotype in the induction of autoimmune diseases in Mycoplasma pneumoniae infection

Mycoplasma pneumoniae (MP) infection is associated with the emergence of various autoimmune disorders and autoantibody production. The most common autoantibodies induced are of anti-I specificity and express cold agglutinin (CA) activity. However, the mechanisms by which the microbial infection triggers the appearance of these autoantibodies are still unknown. To investigate these mechanisms, we used BALB/c mice as experimental models. In this paper, we show that BALB/c mice polyclonal antisera to MP react with human CA IgMs, and reciprocally, that BALB/c mice polyclonal antisera to human IgM CA react with MP. However, antibodies directed against MP and against CA IgM triggered by both immunizations represent two separate sets of antibodies. This was also confirmed using monoclonal antibodies derived from the immunized mice. Among these MAb we selected a monoclonal antibody MAb1D3 which reveals a cross-reactive idiotope (CRI) shared by human CA and other MIgMs with various autoantibody activities (anti-MAG and anti-IF). The CRI defined by MAb1D3 is a recurrent interspecies idiotope that is expressed by post infectious IgM antibodies to MP. Hence, we present in this study new data showing that the concomitant appearance of CAs and anti-MP IgM antibodies during acute MP infection is the consequence of a common idiotypic regulation of antibodies to infectious and to self antigens.

Mycoplasma pneumoniae associated with severe autoimmune hemolytic anemia: case report and literature review

We report a case of severe hemolytic anemia following Mycoplasma pneumoniae infection in a 29-year-old male patient who was treated with azithromycin. Direct Coombs' test was strongly positive and the cold agglutinin titer was high, with anti-I specificity. Antimycoplasma antibody titer by complement fixation was high 1:10,240. The patient was discharged after 12 days of hospitalization in good health. He remains clinically well with no recurrence of jaundice.

Hyperhemolytic transfusion reaction attributable to anti-Fy3 in a patient with sickle cell disease

Abstract A case of hyperhemolytic transfusion reaction attributable to anti-Fy3 in a 30-year-old African American woman with a history of sickle cell disease is reported. The patient was admitted for vaso-occlusive sickle cell crisis and received 4 units of packed RBCs secondary to worsening symptomatic anemia (Hb 5.0 g/dL). On admission, the patient’s antibody screen and identification showed anti-V and anti-E, and her antibody history included anti-E, -C, -Jkb, -N, -V, -S, -Sla, and a cold agglutinin with possible anti-I specificity. A DAT performed on her RBCs was negative. RBC units that lacked E,C,Jkb,N,V,and S were transfused. Posttransfusion Hb was 8.9 g/dL. On day 10 she developed a fever of 103°F, and on day 11 her Hb decreased to 6.4 g/dL. She complained of severe back pain and dark urine. In addition, she became hypertensive, tachycardic, and jaundiced. The DAT indicated the presence of IgG on the patient’s RBCs. Anti-Fy3 was identified in the serum and eluate. During the next 24 hours,her Hb decreased to 2.4 g/dL. The LDH level was 1687 U/L, and her reticulocyte count was 2.6%. A delayed hemolytic transfusion reaction with hyperhemolysis secondary to anti-Fy3 was suspected and was successfully treated with IVIG and high-dose prednisone. To the best of our knowledge, this is the first published case of hyperhemolysis in sickle cell disease attributable to anti-Fy3. Immunohematology 2008:24:45–51.

A Case of Recurrent Paroxysmal Cold Hemoglobinuria With the Different Temperature Thresholds of Donath-Landsteiner Antibodies

In this article, we first report a case of recurrent paroxysmal cold hemoglobinuria with serologic confirmation. On 2 occasions, the Donath-Landsteiner (DL) antibodies belonged to an IgM subclass and showed neither anti-P nor anti-I specificity. Furthermore, it is very interesting that the temperature thresholds of DL antibodies were different on each occasion. Although acute paroxysmal cold hemoglobinuria is considered to be self-limited and transient, we should be careful of its possible recurrence. DL tests must be repeated after the complete recovery from the first episode, with careful attention to several possible causes of false-negative DL tests.

Correspondence

Rituximab (anti-CD20 monoclonal antibody) represents a new interesting tool for treating B-cell malignancies, especially low-grade lymphomas (McLaughlin et al, 1998). To our knowledge, only one paper has reported on the efficacy of this agent for treating cold agglutinins and refractory autoimmune haemolytic anaemia (AIHA) complicating B non-Hodgkin's lymphoma (Lee & Kueck, 1998). We would add a similar clinical case in which this monoclonal antibody has played a significant role. A 73-year-old Caucasian man was admitted to the Haematology Department to December 1997 because of fatigue and anaemia. His past medical history was unremarkable. Physical examination found the patient to be icteric and he did not have hepatosplenomegaly or lymphadenopathy. Haemoglobin (Hb) was 8·5 g/dl, reticulocytes were 190 × 109/l, haematocrit was 25%, mean corpuscular volume (MCV) was 104 fl, platelets were 383 × 109/l, white blood cells were 6·3 × 109/l including 58% neutrophils, 1% eosinophils, 1% basophils, 33% lymphocytes and 7% monocytes. Biochemical evidence of haemolysis was supported by the following results: increased bilirubin at 51 μmol/l, lactate dehydrogenase (LDH) at 495 IU/l (normal < 450 IU/l) and haptoglobin below the detection limit. Serum protein electrophoresis and immunofixation were normal. Immunoglobulin (Ig) levels were: IgG 11·7 g/l, IgA 4·86 g/l and IgM 1·14 g/l. The direct anti-globulin test was positive for polyvalent serum (++++), complement (++++) and IgG (weak). Cold agglutinins of the IgM type, showing anti-I specificity, were strongly positive with a titre of 1/4096. Serologies for human immunodeficiency virus (HIV), hepatitis B and C, syphilis and mycoplasma were negative. A nodular infiltration by CD20-positive lymphoplasmacytic cells was evidenced at the trephine biopsy. This cell population was not detected in peripheral blood on morphological or immunophenotypical investigations. Beta-2 microglobulin was 3 mg/l (normal < 2 mg/l). No lymphadenopathy was seen on thoracic and abdominal computerized tomography (CT) scans. This picture was suggestive of bone marrow-localized low-grade B non-Hodgkin's lymphoma. The patient (body weight: 60 kg) was initially treated with oral cyclophosphamide (100 mg/d) and prednisolone (1 mg/kg/d) plus folic acid. Four weeks after introduction of therapy, his Hb was about 10 g/dl. As soon as steroids were decreased, haemolytic signs reappeared. By May 1998, Hb was 12·7 g/dl with 60 mg/d prednisolone alone. Again, steroids were tapered until 25 mg/d in January 1999. During this period, Hb continued to fall below 10 g/dl. In spite of increased dosage of steroids up to 70 mg/d, Hb levels did not improve. Then, in May 1999, the patient was placed under cyclosporin up to 400 mg/d with reduced doses of prednisolone. Because of lack of efficacy and significant renal toxicity, this treatment was stopped in July 1999. Then, five monthly intravenous boluses of cyclophosphamide were given without any change of transfusional needs. The patient refused to receive polychemotherapy and was under high-dose oral prednisolone (100 mg/d). Three therapeutic plasma exchanges were performed in November 1999. All these modalities did not induce a significant effect on Hb levels and transfusion requirements. This man demonstrated a high degree of steroid-related toxicities including cushingoid facies, myopathy and osteoporosis. Furthermore, by December 1999, 33 units of red cells had been transfused since diagnosis, inducing a marked haemochromatosis picture (serum ferritin, 5093 μg/l; normal, 19–495 μg/l). Considering the experience of Lee & Kueck (1998), our patient was treated from mid-December 1999 with four weekly injections of rituximab at 375 mg/m2 (Mabthera®, Laboratoires Roche, Neuilly, France). No side-effects were noted. Red cell transfusions were stopped after the second rituximab infusion and the Hb level raised above 10 g/dl in January 2000. Under this therapy, at the last evaluation performed 9 months later, this man remained transfusion free and demonstrated a Hb level of 12·5 g/dl with normal bilirubin, LDH and haptoglobin levels. Nevertheless, the direct anti-globulin test remained positive. No haemolysis relapse has been observed to date in spite of the tapering and arrest of corticosteroids. As in the case report of Lee & Kueck (1998), our patient had a marrow-localized CD20-positive chronic lymphoproliferative disease, cold agglutinins and a severe AIHA. This latter manifestation was unresponsive to steroids (albeit an initial response was obtained), cyclophosphamide, cyclosporine or plasma exchange. It is clear that, in this case, rituximab was active against the haemolytic phenomenon. The tolerance was excellent. Interestingly, the response was relatively rapid and no evidence of relapse has been noted 9 months after therapy initiation. Clinicians must be aware of this therapy tool in such severe situations. Reporting of further cases may provide important information regarding the management of refractory AIHA in this setting.

A Boy with Summer Onset Paroxysmal Cold Hemoglobinuria Induced by Donath-Landsteiner Antibody with Anti-I Specificity

A Boy with Summer Onset Paroxysmal Cold Hemoglobinuria Induced by Donath-Landsteiner Antibody with Anti-I Specificity

Coexistence of erythrocyte agglutination and EDTA-dependent platelet clumping in a patient with thymoma and plasmocytoma.

For 8 years, EDTA-dependent pseudothrombocytopenia was observed in a 55-year-old woman with a history of rheumatoid arthritis who had undergone surgery for lymphoepithelial thymoma 11 years earlier. The clinical picture was characterized by the presence of platelet clumps and antiplatelet antibodies of the IgM class. With the recent appearance of a solitary extramedullary plasmocytoma in the right retrobulbar region and the detection of an IgGlambda monoclonal gammopathy, blood examination also revealed erythrocyte agglutinates alongside the platelet clumps and the presence of a cold IgG antibody with antiI specificity. Both phenomena were observed in vitro when the sample temperature declined to 20 degrees C to 25 degrees C, but not at 37 degrees C. While the EDTA-dependent antiplatelet antibodies did not appear to be chronologically correlated with the patient's diseases, the cold antierythrocyte autoantibodies were strictly related to the plasmocytoma and the IgGlambda monoclonal component in serum. To our knowledge, this is the first description of an association between EDTA-dependent platelet and erythrocyte agglutinates, with a clinical picture of pseudothrombocytopenia and pseudoerythrocytopenia due to cold agglutinins.

Index of Suspicion

Index of Suspicion

Rifampicin-associated acute renal failure: Pathophysiologic, immunologic, and clinical features

A 71-year-old woman was treated for a relapsing pulmonary tuberculosis with reinstitution of rifampicin after a medication-free interval of 2 years. After ingestion of the second dose, she developed severe hemolytic anemia and acute renal failure (ARF) necessitating dialysis. We demonstrated the presence in the patient's serum of rifampicin- dependent immunoglobulin G (IgG) and IgM antibodies, which caused red blood cell lysis through interaction with the I antigen on the erythrocyte surface. A review of the literature yielded 48 cases of rifampicin-associated renal failure. A subgroup of 37 patients could be distinguished, which, analogous to our case, suddenly developed ARF and frequently also developed hemolytic anemia and/or thrombocytopenia during intermittent or interrupted treatment. Regarding the pathogenesis of the ARF, renal biopsy consistently revealed tubular lesions. Although intravascular hemolysis with hemoglobinuria may play a role, it is not uniformly present. Our demonstration of an antibody with anti-I specificity provides a possible explanation. The I antigen is also expressed on tubular epithelium and may, therefore, be the target structure through which rifampicin-antibody complexes lead to tubular cell destruction. The other cases of rifampicin-associated ARF were unrelated to this subgroup: two cases of rapidly progressive glomerulonephritis, five cases of acute interstitial nephritis, and four cases of light chain proteinuria were recorded. (Am J Kidney Dis 1998 Jan;31(1):108-15)

Cold agglutinin activity is common among human monoclonal IgM Rh system antibodies using the V4-34 heavy chain variable gene segment.

The V4-34 gene segment is commonly used by human monoclonal IgM alloantibodies against blood group antigens and by cold-reactive red cell autoantibodies with anti-I or anti-i specificity. This study was conducted to determine whether cold agglutinin activity is found among the V4-34-encoded alloantibodies. Fifty-four human IgM monoclonal antibodies (MoAbs) against Rh system antigens were tested for cold agglutinin activity against red cells lacking the relevant Rh system antigen and for reactivity with tissue I and/or i antigens using immunohistochemistry. The findings were correlated with the utilization of the V4-34 segment as determined in an enzyme-linked immunosorbent assay with an antibody (9G4) that is specific for this gene product and were also correlated with other serologic properties. Of the MoAbs, 59 percent were 9G4-positive. Of the 9G4-positive subset, 16 and 44 percent agglutinated native adult (express I) and cord (express i) cells, respectively, at 4 degrees C; these levels rose to 84 and 94 percent, respectively, with the use of papain-treated cells. The red cell antigens recognized at 4 degrees C were cleaved by endo-beta-galactosidase, which is consistent with their being I and i. Of the 9G4-positive subset, 53 percent bound to tissue i antigen. These reactivities were not found among 9G4-negative MoAbs. Endo-beta-galactosidase treatment of red cells enhanced Rh system antibody agglutination by 9G4-negative MoAbs. Anti-I/i reactivity is common among IgM Rh system MoAbs and is shown only by the V4-34-encoded subset. This finding has implications for the use of MoAbs for Rh system typing of blood.

Activation of complement by cold agglutinins.

To review recent reports on the interaction of cold agglutinins with the complement system and its relevance to cold agglutinin disease. Review articles and original papers have been selected for this contribution. The report focuses on experimental data available from in vitro studies as well as clinical findings regarding the mechanisms of cold agglutinin-induced complement activation. Despite the observation that only few cold agglutinins (almost exclusively IgM molecules with anti-I specificity) induce in vitro hemolysis of human red blood cells with human serum (homologous system), the vast majority of these autoantibodies are able to initiate the classical pathway sequence with the fixation of C1 and to a lesser degree of C4. The ability of IgM cold agglutinins to activate, in principle, complement is demonstrated by their hemolytic efficiency in the presence of animal serum as a source of heterologous complement. In addition to the thermal amplitude of cold agglutinin binding, a possible interference with membrane regulatory proteins may render certain cold agglutinins hemolytically active in a homologous system. Despite a hemolytic inefficiency, cold agglutinin-induced fixation of early complement components up to C3 leads to an accelerated clearance of red cells from the circulation by hepatic sequestration. However, it is not yet clear, to what degree these cells are eliminated by the reticuloendothelial system or whether they return to the circulation. Dependent on the amount of membrane-bound C3 fragments these cells may even be protected against further cold agglutinin-induced complement attack.

VH4.21-encoded natural autoantibodies with anti-i specificity mirror those associated with cold hemagglutinin disease.

The Ig VH regions of virtually all human pathogenic cold agglutinin (CA) anti-i/l autoantibodies are encoded by a single Ig VH gene segment, VH4.21, in conjunction with a highly variable CDR3 structure. The anti-I specificity is often associated with V kappa III-encoded L chains, whereas anti-i autoantibodies appear to use a broader array of kappa and lambda VL gene segments. B cells expressing VH4.21 are abundantly present in adult lymphoid tissues from healthy individuals but their relationship with B cells secreting pathogenic CA is unknown. Herein we have analyzed the distribution of VH4.21-expressing B cells in fetal, neonatal, and adult B cell populations using the monoclonal anti-VH4.21 antibody 9G4. In addition, we have analyzed the anti-i and anti-I binding capacity and V regions of 19 VH4.21-encoded mAb secreted by cord and adult blood-derived cell lines from healthy individuals. The results show that VH4.21 expressing B cells are overrepresented in all repertoires studied and are evenly distributed over cord blood CD5+ and CD5- B cell populations. VH4.21-encoded H chains strongly predispose for anti-i binding capacity, regardless of the VL regions or H chain CDR3 structure. The avidity of some of these antibodies was similar to those of pathogenic CA. In addition, we found evidence for monospecific anti-I binding in antibodies encoded by other members of the VH4 gene family. We conclude that VH4.21-encoded antibodies with anti-i specificity from the normal B cell repertoire mirror their pathogenic counterparts and that naturally occurring anti-I antibodies may be encoded by a more diverse array of VH4 genes.

Naturally occurring anti-i/I cold agglutinins may be encoded by different VH3 genes as well as the VH4.21 gene segment.

In the current study, we wished to determine if the V regions encoding the naturally occurring anti-i/I Cold Agglutinins (anti-i/I CA) differ from pathogenic anti-i/I CA that are exclusively encoded by the VH4.21 gene. After EBV transformation of B lymphocytes, we generated one anti-I secreting clone from each of two individuals; clone 4G (individual CM, PBL) and clone Sp1 (individual SC, spleen). Clone 4G expresses a VH3 gene sequence that is 92% homologous to the germline gene WHG26. Clone Sp1 also expresses a VH3 gene that is 98% homologous to the fetally rearranged M85/20P1 gene. Another clone, Sp2 (anti-i specificity), from individual SC is 98% homologous to the germline gene VH4.21. For correlation, we studied anti-i/I CA fractions purified from 15 normal sera and found no or relatively small amounts of 9G4 (VH4.21 related idiotype) reactive IgM. Five cold agglutinin fractions contained large amounts of VH3-encoded IgM (compared to pooled normal IgM) by virtue of their binding to modified protein Staph A (SPA), and absorption of three CA fractions with modified SPA specifically removed anti-i/I binding specificity entirely. Collectively, the data indicate that naturally occurring anti-i/I CA may be encoded to a large extent by non-VH4.21-related genes, and that the VH4.21 gene is not uniquely required for anti-i/I specificity.

Immune hemolytic anemia and renal failure associated with rifampicin-dependent antibodies with anti-I specificity

A 50-year-old woman with primary biliary cirrhosis developed immune hemolytic anemia and renal failure while receiving rifampicin for the treatment of refractory pruritus. Serological studies revealed the presence of rifampicin-dependent antibodies of the IgM class that, when tested against a wide panel of erythrocytes, had anti-I specificity. Subsequently, rifampicin was withdrawn and prednisone treatment instituted, this resulting in a rapid resolution of the hemolysis, whereas hemodialysis was required for recovery of the renal function. A role is suggested for the anti-I specificity of the antibodies in the development of renal failure associated with rifampicin therapy.

Cold agglutinins in haemophiliac boys infected with HIV.

Eleven haemophiliac boys infected with HIV were screened for irregular red cell antibodies and were compared with nine haemophiliac boys who did not have antibodies to HIV. Seven (64%) of the children who had antibodies to HIV also had cold agglutinins, mostly of anti-I specificity, compared with one (11%) of those who did not have antibodies to HIV. The children with antibodies to HIV and cold agglutinins had a significantly increased mean IgM concentration. The presence of cold agglutinins was not correlated with T4 lymphocyte count, symptoms of HIV infection, serum beta 2 microglobulin concentrations, concentrations of IgG or IgA, or with the evidence of past infection with cytomegalovirus or Epstein-Barr virus.