Lawrence D. Petz

Drug-induced immune hemolytic anemia

Drug administration causes from 16 to 18 per cent of cases of acquired immune hemolytic anemia. The pathogenesis of erythrocyte sensitization by drug-related antibody with or without fixation of complement is variable, and there is a relationship between the responsible drug, the mechanism of red cell sensitization, clinical manifestations and laboratory methods of diagnosis. Drugs such as phenacetin and quinidine form a complex with the antidrug antibody, and the immune complex attaches to red cells usually fixing complement and causing acute intravascular hemolysis. Other drugs (e.g., penicillins), when given in large doses, coat normal red cells in vivo and in some patients a high titer IgG anti-drug antibody develops which reacts with the coated cells. Hemolytic anemia may develop with red cell destruction being primarily extravascular. Cephalosporins cause positive direct antiglobulin tests in a small percentage of patients either by the same mechanism as penicillins or by modification of the red cell membrane leading to nonimmunologic absorption of serum proteins. Hemolytic anemia has been reported only rarely. A few drugs (notably alpha methyldopa) cause the development of autoimmune hemolytic anemia. Knowledge of clinical manifestations and laboratory aids to diagnosis is necessary to distinguish immunohematologic abnormalities caused by drugs from other causes.

The sickle cell hemolytic transfusion reaction syndrome

BACKGROUND: Patients with sickle cell anemia may develop serious, life‐ threatening hemolytic transfusion reactions (HTRs). More severe anemia may develop after the HTR than was present before transfusion, which suggests the possibility of an increased rate of hemolysis of autologous red cells. STUDY DESIGN AND METHODS: The signs and symptoms occurring during eight severe HTRs that occurred in five patients with sickle cell anemia were reviewed, as were published reports by other investigators. Calculations of red cell production and destruction incorporating known correction factors for reticulocyte maturation were performed to determine the most probable mechanism for the striking drop in hematocrit observed in several instances. RESULTS: A characteristic constellation of findings was recognized in some severe HTRs in patients with sickle cell anemia. Calculations of daily red cell production and senescence indicated that a marked drop in hematocrit occurs when erythropoiesis is suppressed in a patient with a short red cell life span and that this could account for severe posttransfusion anemia when donor red cells are hemolyzed during an HTR. CONCLUSION: A sickle cell HTR syndrome was defined. A rapid increase in the severity of anemia occurs in patients with sickle cell anemia when all donor red cells are hemolyzed during an HTR and when there is suppression of erythropoiesis, as commonly occurs as a result of transfusion or concomitant illness. Although an increased rate of hemolysis of autologous red cells may also occur, more definitive data are required to document that in these patients.

Immunohematologic consequences of major ABO-mismatched bone marrow transplantation.

Twelve of 58 (21%) evaluable patients of blood group 0 who received a bone marrow transplant (BMT) from an HLA-matched sibling of a donor of group A or B developed significant immunohematologic problems in the posttransplant period. Anti-A or anti-B isohemag-glutinins persisted for longer than 120 days post-BMT in nine patients and are still present in three patients at days +162 to +605. Red cell production as indicated by a reticulocyte count of > 0.5% was delayed to 40 days or more in nine patients, and in five of these was markedly delayed to 170 days or longer. One patient does not as yet have red cell production on day +605 in spite of having had 13 plasma exchanges performed to reduce the anti-B titer. Five patients experienced overt hemolysis, manifested by a sudden drop in hemoglobin of 1.5 to 4 gm/dl (median = 2.5 mg/dl), starting on day +37 to +105 (median = +65), persisting for 10 to 94 days (median = 36 days). Hemolysis and a delay in the onset of erythropoiesis beyond 170 days were more frequent in 30 patients treated with cyclosporine/prednisone than in 28 patients treated with methotrexate/prednisone for graft-versus-host disease prophylaxis. Our data indicate that ABO major mismatched BMT can be associated with significant immunohematologic consequences, some of which occur more frequently in association with cyclosporine administration.

Transfusion-associated graft-versus-host disease in immunocompetent patients: report of a fatal case associated with transfusion of blood from a second-degree relative, and a survey of predisposing factors.

A patient without evident immune deficiency who received a transfusion of blood from a second‐degree family member developed fatal transfusion‐ associated graft‐versus‐host disease (TA‐GVHD). The donor was homozygous for an HLA haplotype for which the recipient was heterozygous (one‐way HLA match). All 39 reported cases of TA‐GVHD in immunocompetent patients were reviewed to ascertain the predisposing factors and to define the indications for irradiating blood for this population. HLA typing was described in 15 cases; in 13, including seven related and six unrelated donors, a one‐way HLA match was present. Thirty‐one (79%) of the 39 cases were reported from Japan (and 196 other cases are cited in the Japanese literature), but a one‐way HLA match among unrelated donors at HLA‐A, ‐B, ‐DR loci is only approximately two to four times more likely in Japanese persons than in whites. Fresh blood (< 96 hours old) was used in 29 (94%) of the 31 cases reported from Japan and in 33 (87%) of 38 cases overall (in one case, the age of the blood used was not reported). Thus, factors that appear to predispose to TA‐GVHD in immunocompetent patients are a one‐ way HLA match, fresh blood, and, possibly, Japanese ancestry. Irradiating cellular blood components from all blood relatives of transfusion recipients will not completely eliminate the risk of TA‐ GVHD.

Selecting donors of platelets for refractory patientson the basis of HLA antibody specificity

BACKGROUND: Patients who are refractory to platelet transfusion as a result of HLA alloimmunization are generally given HLA‐matched or crossmatched platelets. However, HLA‐matched platelets that are matched at HLA‐A and ‐B loci (A‐matched) or those without any mismatched or cross‐reactive antigens (BU‐matched) are frequently unavailable. A disadvantage of crossmatching is that crossmatched platelets have a shelf life of only 5 days, so that crossmatch tests must be performed frequently for patients requiring long‐term platelet transfusions. An alternative method is the selection of platelets according to the patients HLA antibody specificity, called the antibody specificity prediction (ASP) method.

Selection of platelets for refractory patients by HLA matching and prospective crossmatching.

A multi‐site clinical study compared platelets chosen for refractory patients by prospective platelet crossmatching using stored donor platelets and HLA‐based selection. Seventy‐three patients who were refractory to random‐donor platelets received two plateletpheresis components, one chosen by HLA‐based criteria and the other by crossmatching. Patients were carefully evaluated to exclude nonimmune factors that could adversely affect transfusion results. Each of the five study sites used a crossmatch procedure with which it had experience. Results from this study indicate the following: 1) The overall rate of successful transfusion was similar when an HLA‐based method of donor selection that includes all grades of matching and mismatching was compared to a crossmatch‐based method of donor selection. 2) HLA‐based selection that restricts recipients to grade A and BU matches was superior to a selection method based upon crossmatching alone. Donor selection based on HLA matching (grades A or BU) was also superior to selection based on any degree of HLA mismatching (grades BX, C, or D). 3) Selection of donors based on HLA‐ cross‐reactive groups (defined by in vitro serologic crossreactivity) was no more successful than that based on grade C and D mismatches and was no more successful than selection by crossmatching alone. 4) Lymphocytotoxic and platelet antibodies were not detected in many of the enrolled patients, even though patients demonstrating nonimmune factors were eliminated from the study. It can be concluded that HLA‐ compatible (grades A and BU) platelets provide optimal support for refractory patients, but that crossmatch‐selected platelets are acceptable as an alternative component.

Disulfide bonds are a requirement for Kell and Cartwright (Yta) blood group antigen integrity

Summary. We have investigated the effect of dithiothreitol (DTT) upon the Kell blood group system and other red cell antigens. All Kell blood group antigens studied (K, k, Kpa, Kpb, Jsa, Jsb and Ku) as well as the Cartwright (Yta) antigen were completely denatured after treatment with DTT. The Gerbich antigen was substantially weakened but not completely denatured. The Jsa and Jsb antigens appear to have an exquisite sensitivity to treatment with DTT and can be completely denatured using very low concentrations (≤2 mm) whereas other Kell system antigens require much higher concentrations of DTT for their denaturation (100–200 mm). Of 38 other blood group antigens investigated, only the Yta antigen was completely denatured using 200 mm DTT. Furthermore, the Yta antigen was denatured within the same concentration range as Kell and one can speculate that this indicates some biochemical relationship between these two blood group systems. From our results, we conclude that: (1) at least two distinct disulfide (S–S) bonds are required for maintenance of the Kell blood group antigen system; (2) Jsa and Jsb antigens are distinctly different from other Kell system antigens based upon sensitivity to treatment with DTT; these antigens may be located on a different antigenic domain; and (3) the Yta antigen requires at least one disulfide bond for its maintenance of antigen integrity. Although the Gerbich antigen was not completely denatured, results indicate that disulfide bonds may also be important structural determinants for these antigens.

HEMOLYSIS ASSOCIATED WITH TRANSPLANTATION

emolysis resulting from a variety of mechanisms has been noted after the transplantation of bone marrow or solid organs and has arisen from donor-derived antibodies, recipient-derived antibodies, and nonimmune mechanisms. Diagnosis and appropriate management require an understanding of the settings in which hemolysis may occur and of its numerous causes. Many cases of hemolysis following allogeneic bone marrow transplantation (BMT) are caused by an immune mechanism and are related to the fact that inheritance of blood group antigens is independent of the HIAgene complex.Thus, even ifthe donor and recipient are HIA-matched, their red cells (RBCs) may have clinically important phenotypic differences. There may be a “minor” blood group incompatibility in which donor’s immune system is capable of producing antibodies against the recipient’s RBC antigens (e.g., group 0 donor and group A recipient) or a “major” blood group incompatibility in which the recipient’s immune system is capable of making antibody against the donor’s RBC antigens (e.g., group A donor and group 0 recipient). A well-recognized syndrome of immune hemolysis following BMT has become known as the passenger lymphocyte syndrome.l-‘j It occurs in a minority of the patients for whom there is a minor ABO blood group mismatch between donor and recipient. Hemolysis usually has its onset between Days 5 and 15 after transplant, is often abrupt in onset, and may be severe, with a rapidly dropping hemoglobin level, signs of intravascular hemolysis, and renal failure. Anti-A and/or anti-B directed against antigens on the patient’s RBCs are found in the serum and in eluates from the patient’s RBCs. Hemolysis subsides as the patient’s residual incompatible RBCs are destroyed and are replaced by newly produced RBCs of donor origin andlor by transfused group 0 RBCs. Detailed serologic studies have indicated that the relevant serum antibody is not present in the immediate posttransplant period but is first detectable around the time hemolysis begins. Therefore, passive transfer during infu-

Selection of unrelated cord blood grafts

To the editor: We are concerned about statements in the article by Barker et al,[1][1] who describe a factor of 0.75 × TNC (total nucleated cell) to “correct” the TNC content of RBC-replete cord blood units. No data are provided to justify such an opinion, and the authors cite only “personal

The correlation of cold agglutinin titrations in saline and albumin with haemolytic anaemia.

Cold agglutinin syndrome (CAS) is usually associated with IgM cold agglutinins with titres exceeding 1000 at 4deg;C and a thermal amplitude of 30‐32deg;C. Occasionally patients are encountered who although having clinical and laboratory findings compatible with CAS do not have the characteristic serological findings. Thirty‐two patients with a positive direct antiglobulin test due to complement sensitization were studied. Thirty‐one of these patients had cold agglutinin titres greater than 64. Twenty‐eight had haemolytic anaemia, including one patient with a cold agglutinin titre of only 8 against saline‐suspended red cells. 53.6% of sera from patients with haemolytic anaemia reacted at 30deg;C and 7.1% at 37deg;C when albumin was not present, whereas in the presence of albumin all of the sera reacted at 30deg;C and 67.9% reacted at 37deg;C. None of the four patients without haemolytic anaemia reacted at 30deg;C or 37deg;C in the presence of albumin, even though one serum reacted to a titre of 1280 at 4deg;C. Cold agglutinin titres and thermal amplitudes in the presence of bovine albumin were found to correlate better with haemolytic anaemia than reactions without albumin. If bovine albumin is utilized in compatibility testing, multiple cold autoabsorptions may be necessary before alloantibody activity at 37deg;C can be excluded.