David F. Stroncek

Therapeutic apheresis for babesiosis.

Infection with the tick‐borne protozoa Babesia is becoming more common. Babesiosis is usually successfully treated with antibiotics but, in some cases, apheresis may also be indicated. We report two patients with babesiosis and hemolysis treated by apheresis and antibiotics. One case had traditional indications for red blood cell (RBC) exchange, and a second patient was treated with RBC exchange, and plasmapheresis for hemolysis, probably secondary to Babesia parasitemia. Case 1 involved a 44‐year‐old man with chronic relapsing pancreatitis who had become infected with Babesia from a unit of RBCs transfused during surgery. At 5 weeks after surgery, fever and severe hemolysis developed, along with a hemoglobin of 69 g/L; 30% of his RBCs were found to be infected with Babesia. This patient had several postoperative complications; the babesiosis was treated with clindamycin, quinine, and three RBC exchanges. Parasitemia fell to less then 1% of RBCs, but the patient died of pancreatitis.

Treatment of alloimmune neonatal neutropenia with granulocyte colony-stimulating factor

Despite numerous attempts to increase the neutrophil count of infants with alloimmune neonatal neutropenia, no therapy has been consistently effective. We describe two infants with alloimmune neutropenia who had a rapid and prolonged increase in neutrophil number after treatment with granulocyte colony-stimulating factor (G-CSF). Patient 1 had antibody directed against the neutrophil antigen NA2. He received three daily doses of G-CSF, and within 2 days his neutrophil count increased from 0.350 x 10(9) to 3.584 x 10(9)/L (350 to 3584/mm3). Despite cessation of treatment the neutrophil count remained in the normal range. Patient 2 had antibody to the neutrophil antigen NA1, and received six daily doses of G-CSF. Within 4 days his neutrophil count increased from 0.477 x 10(9) to 4.320 x 10(9)/L (477 to 4320/mm3) and remained in the normal range for 11 days after the last dose of G-CSF. We recommend that treatment with G-CSF be considered for selected infants with alloimmune neutropenia.

Drug-Induced Immune Neutropenia

Drug-induced immune-mediated neutropenia is a serious complication of therapy with many different drugs. Its clinical presentation and outcome are highly variable. In addition to the drugs listed in this review it is likely that many other drugs also cause immune-mediated neutropenia but drug-dependent neutrophil antibodies were not reported because of the lack of widespread availability of testing. With the exception of quinine-dependent antibodies in three patients, the neutrophil antigens recognized by the drug-dependent antibodies are not known; however, the recent development of MAIGA assays will likely help identify the antigens other drug-dependent neutrophil antibodies recognize.

Neutrophil-Specific Antigen NB1 Is Anchored Via a Glycosyl-Phosphatidylinositol Linkage

Neutrophil‐Specific alloantibodies and the antigens they recognize are important in clinical medicine but little is known about the structure of these antigens. Alloimmunization to the antigen NB1 is a clinically important cause of neonatal neutropenia and leukocyte‐mediated transfusion reactions. A novel mechanism of protein attachment to cell membranes involving the covalent linkage of the protein through an oligosaccharide to phosphatidylinositol has recently been defined. Many proteins which are anchored to the cell membrane by this mechanism can be released by treatment with phosphatidylinositol‐specific phospholipase C (PI‐PLC). The 58–64‐kDa human neutrophil surface protein which contains the NB1 antigen was labeled with 125I by using lactoperoxidase and examined for PI‐PLC sensitivity. The 58–64‐kDa protein was specifically released from the cell by treatment with PI‐PLC, and the mobility of the protein under non‐denaturing conditions using non‐ionic detergent was increased by treatment with PI‐PLC. Surface expression of the NB1 antigen was slightly up‐regulated by treatment with the chemotactic peptide f‐met‐leu‐phe. Removal of N‐linked carbohydrates with endoglycosidase‐F decreased the apparent molecular weight of the protein to ~45‐kDa. The data suggest that most of the 58–64‐kDa protein bearing the neutrophil‐specific antigen NB1 is anchored to the membrane through a glycosyl‐phosphatidylinositol linkage.

Neutrophil alloantibodies react with cytoplasmic antigens: a possible cause of false-positive indirect immunofluorescence assays for antibodies to neutrophil cytoplasmic antigens.

Antibodies to neutrophil cytoplasmic antigens (ANCA) can be detected in patients with Wegeners granulomatosis and systemic vasculitis. During pregnancy or following transfusion, subjects sometimes produce alloantibodies to neutrophil antigens. If patient sera being tested for ANCA contain alloantibodies directed at neutrophil antigens that residue in the cytoplasm, the results may be difficult to interpret. At least one neutrophil antigen, NB1, is expressed on both neutrophil plasma membranes and secondary granules. We tested alloantibodies specific for neutrophil antigens NA1, NA2, NB1, NB2, 5b, 9a, and Mart in an ANCA-indirect immunofluorescence (ANCA-IF) assay to determine if these alloantibodies reacted with neutrophil cytoplasmic or granule antigens. Alloantibodies specific for neutrophil antigens NA1, NA2, NB2, 5b, and 9a did not react with neutrophil cytoplasmic components. However, all three NB1 alloantibodies studied demonstrated a cytoplasmic pattern of immunofluorescence (C-ANCA) when NB1-positive neutrophils were tested. While control ANCA resulted in cytoplasmic immunofluorescence of all neutrophils from each donor tested, NB1 antibodies reacted with a subpopulation of neutrophils from some donors. Cytoplasmic immunofluorescence was also observed with an antibody directed against the Mart neutrophil antigen. The Mart antigen is located on integrin CR3 (CD11b/CD18). To confirm that these reactions were due to anti-Mart, monoclonal antibodies to CD11b and CD18 were also tested and found to cause cytoplasmic immunofluorescence. When the ANCA-IF assay was performed using neutrophils that did not express Mart or NB1 antigen, cytoplasmic immunofluorescence was seen with the ANCA control antisera, but not with the NB1 or Mart alloantibodies.(ABSTRACT TRUNCATED AT 250 WORDS)

Lack of relation of granulocyte antibodies (antineutrophil antibodies) to neutropenia in children with human immunodeficiency virus infection

BACKGROUND Neutropenia in children and adults with HIV infection is frequently observed, perhaps as a result of impaired myelopoiesis, drug myelotoxicity, immune destruction or opportunistic infection. The presence of antineutrophil antibodies (granulocyte antibodies) has been associated with severe neutropenia in some reports but not in others, and such antibody assays can be confounded by the presence of immune complexes and HLA antibodies. METHODS To determine both the prevalence of granulocyte antibodies in children with HIV infection and whether such antibodies were related to neutropenia, we screened the sera of 30 HIV-infected children by performing granulocyte immunofluorescence, granulocyte agglutination and lymphocytotoxic anti-HLA antibody assays. Reactivity was graded by a standard numeric score calculated per number of reactive cells. RESULTS Of 26 evaluable sera, 16 (62%) had granulocyte antibodies, 6 (23%) had HLA antibodies and 4 (15%) had neither. There was no correlation between presence of granulocyte antibodies and degree of neutropenia. CONCLUSIONS We conclude that granulocyte antibodies are highly prevalent in children with HIV infection but do not correlate with the degree of neutropenia. Antineutrophil antibody determination as currently performed does not appear to be useful in the evaluation of the HIV-infected neutropenic child.

Bone Marrow Donor Registries and International Cooperation

TISSUE and organ sharing between individuals who are unknown to each other is now commonplace. I Indeed, this ever expanding type of altruism is offering a curative approach to many fatal diseases on a daily basis. 2 Bone marrow transplantation (BMT) using unrelated donors is expanding rapidly but, unfortunately, is confined to the Western world at this time. A registry of 100,000 donors may be adequate to find donors for most patients if the donor and patient belong to a homogenous racial group3; but if a country is composed of several different racial groups, then registries of that size will be needed for each racial group. Because building registries is expensive, no country, especially smaller ones, can carry out this activity without international cooperation. The racial and ethnic makeup of many countries makes the international sharing of unrelated bone marrow donors essential for optimal and efficient management of this resource. aur goal in this review is to provide an overview of how bone marrow donor registries operate; outline the mechanism for sharing international, unrelated bone marrow donors; review the current results of searches for unrelated bone marrow donors; and discuss the prospects for the future. The bone marrow from an unrelated donor comes from an individual who is a member of a registry of donors within a specific country. Each registry has its own rules and regulations for membership, but the general intent when joining is to make oneself available to donate bone marrow anonymously when requested to do so. Before becoming part of a registry adonor should understand the basic process of bone marrow donation, be tissue-typed, and be free of any infectious markers as is required for blood donation. Basically, bone marrow donation entails a general or regional anesthetic, 2 days in the hospital, and several days of recovery. The marrow is harvested from the brim of the pelvis, distant from any joints or the spine. Complications are rare when one considers the worldwide experience with both related and unrelated bone marrow donors. 4 •5 •6 ,7 However, most registries have more stringent criteria for unrelated compared with related bone marrow donors.

Are Antineutrophil Antibodies (Granulocyte Antibodies) in Children with HIV Infection Causally Related to Neutropenia? ♦ 783

Are Antineutrophil Antibodies (Granulocyte Antibodies) in Children with HIV Infection Causally Related to Neutropenia? ♦ 783