The Fc-receptor III of cultured human monocytes. Structural similarity with FcRIII of natural killer cells and role in the extracellular lysis of sensitized erythrocytes.

FcRIII is not present on peripheral blood monocytes, but becomes expressed upon culturing and can be demonstrated on tissue macrophages. We studied the expression of FcRIII of cultured monocytes in detail and compared its structure with FcRIII of neutrophils and NK cells. The cell density of FcRIII reached a plateau within 3 days of culturing. During that time, the expression of FcRI and FcRIIa, also present on monocytes, did not change significantly. FcRIII on cultured monocytes lacked, as did NK cell FcRIII, the NA1-allotypic variant of the NA system present on the neutrophil FcRIII. Studies with glycosyl-phosphatidyl-inositol-specific phospholipase C and analysis of cells of patients with paroxysmal nocturnal hemoglobinuria revealed that FcRIII on cultured monocytes is not anchored by phosphatidyl-inositol-glycan in the cell membrane. Similarly, FcRIII on NK cells was resistant to glycosyl-phosphatidyl-inositol-specific phospholipase C treatment, suggesting that NK cell FcRIII is also not anchored by a phosphatidyl-inositol-glycan moiety, in contrast to neutrophil FcRIII. Analysis by SDS-PAGE showed that the FcRIII of cultured monocytes had a similar mobility as the FcRIII on NK cells, but was clearly distinct from neutrophil FcRIII. Treatment with N-glycanase showed that the protein backbone of deglycosylated FcRIII of cultured monocytes was similar to that of FcRIII of NK cells, but deglycosylated neutrophil FcRIII was different. Specific blocking of FcRIII of cultured monocytes with an anti-FcRIII mAb did not reduced the lytic action of the cultured monocytes towards sensitized erythrocytes. However, FcRIII was modulated from the cell surface by incubation with sensitized E, whereas non-FcR Ag were not. These findings indicate that FcRIII is involved in binding of immune complexes, but does not act as a trigger molecule for extracellular lysis of sensitized E.

ABO and Rhesus phenotyping of fetal erythrocytes in the first trimester of pregnancy.

Determination of fetal red blood cell antigens in early pregnancy can be important in cases with a history of severe haemolytic disease of the newborn. From chorionic villus biopsies (CVB) between the 8th and 12th week of gestation a small number of fetal red blood cells was obtained, inevitably highly contaminated with maternal blood cells. Two techniques were used to demonstrate the minor (fetal) cell population with a blood group antigen differing from the major (maternal) cell population: a solid-phase microfluorescence technique (introduced in this paper) which was compared with the mixed agglutination technique. In series of artificial mixtures of erythrocytes it was shown that with the microfluorescence technique the ABO and Rhesus phenotypes of minor cell populations could be determined at a ratio of 1 in 4000 erythrocytes of the major population, making this technique 4 times as sensitive as the mixed agglutination technique. We further investigated the reliability of the microfluorescence technique to demonstrate antagonistic fetal blood groups in the first trimester of pregnancy. Of 18 women undergoing CVB prior to therapeutic abortion, blood group antagonism (ABO and Rhesus systems) was demonstrate in all 11 cases in which it was present. Therefore, it seems that CVB can be reliably used for the prenatal diagnosis of (recurrent) blood group antagonism.

Chronic idiopathic and secondary neutropenia: clinical and serological investigations.

Clinical data on 49 patients with chronic idiopathic neutropenia (CIN) and 42 patients with neutropenia secondary to a well-defined immunological disorder (SN) were collected and related to serological parameters. In 47% of the patients with CIN and 53% of those with SN, a positive direct immunofluorescence test was obtained with granulocytes from the patients. In the sera from the patients in the two groups, antibodies against donor granulocytes were detected by the indirect immunofluorescence test, the leucoagglutination test and/or the granulocytotoxicity test in 15%, 19% and 15%, respectively. The results of the above tests could not be correlated with any clinical or haematological parameter. Immune complexes in the serum were detected by the 125I-Clq-binding test in 29% of patients with CIN and in 58% of those with SN. The presence of serum immune complexes correlated well with the existence of a low neutrophil count, but not with the presence of recurrent infections, with bone-marrow abnormalities, or with positive reactions in other serological tests. The sera of eight out of 14 patients with CIN and seven out of 12 patients with SN had inhibitory activity for myeloid colony formation in vitro (CFU-GM). This CFU-GM inhibitory activity was correlated with the presence of recurrent infections and with hypoplasia of the myeloid compartment of the bone marrow, but not with positive reactions in other tests. We conclude that the 125I-Clq-binding test probably detects circulating immune complexes that induce a shift neutropenia, whereas serum activity inhibitory for CFU-GM possibly relates to clinically more serious forms of neutropenia. The significance of neutrophil-bound Ig and granulocyte-reactive antibodies in the serum is not clear.

Effect of the binding of anti-Zwa antibodies on platelet function.

Anti-Zwa antibodies can induce a Glanzmann-like platelet dysfunction in normal Zwa-positive platelets. Although a normal shape change and release reaction was always recorded in response to adenosine diphosphate and collagen, the aggregation on these inducers could be completely inhibited by anti-Zwa antibodies. Analogous to the platelets from patients with Glanzmann's thrombasthenia, normal platelets sensitized with anti-Zwa did not associate with fibrinogen upon exposure to adenosine diphosphate. Our data indicate that the binding site for fibrinogen is closely associated with the Zwa-antigenic determinants on the platelet membrane glycoproteins and thus with glycoprotein IIIa which is known to carry Zwa.

Familial thrombocytopenia associated with platelet autoantibodies and chromosome breakage.

An extended family is described in which three members had thrombocytopenia. These affected members had chromosomal changes resembling those found in Fanconi's anaemia, though they lacked the development defects associated with that syndrome. One had bone-marrow hypoplasia and died of squamous cell carcinoma of the mouth at the age of 27. In addition, all three had platelet autoantibodies not found in any other family members tested. There was no linkage between the thrombocytopenia and HLA groups. The nature of the association of thrombocytopenia, platelet autoantibodies and chromosomal abnormalities in this family remains doubtful.

A comparison of surface marker analysis and FAB classification in acute myeloid leukemia.

Surface marker analysis with rosette tests and a large panel of xenoantisera and monoclonal antibodies was done on the malignant cells of 55 patients with acute myeloid leukemia (AML). The diagnosis was made on morphological and cytochemical grounds, and the leukemias were classified according to the quantified FAB criteria. The marker tests included the E- and EA-rosette test, immunofluorescence with rabbit-polyclonal antisera against human Ig, kappa, and lambda light chains, thymocytes, granulocytes, erythrocytes, platelets, lysozyme, (leukemic) myeloblasts, the common ALL antigen, SB cell-line cells (anti-Ia), and a mouse anti-Ia serum. The monoclonal mouse antibodies applied were anti-T-cell antibody (3A1), two anti-granulocyte-monocyte antibodies (OKM1 and B2.12), four antigranulocyte antibodies (MI/N1, UJ 308, B4.3, and B13.9), an antiplatelet antibody (C17.28), anti-HLA heavy chains (w6/32.HLK), anti-Ia antigen (OKI1), and OKT10. AML cells from many patients lacked the expression of myeloid markers, and we found that a correlation existed between the relative maturity of the leukemia subtype and the extent of positivity for these markers. Surface marker analysis discriminated poorly between the "myeloid" and "monocytoid" subtypes; OKT10 and the "T-cell marker" 3A1 were often expressed on AML cells. In two cases of AML, there was an unexpected expression of platelet antigens with the monoclonal antiplatelet antibody. One of them, classified as M1, was ultrastructurally a megakaryoblastic proliferation with a positive reaction for platelet peroxidase. Only with the help of computerized analysis, was it possible to prove a clear correlation between the surface marker profile and the FAB classification.

Changes in the surface marker pattern related to maturation in adult acute myeloid leukaemia.

Introduction of the maturation index (MI) as a measure for the degree of maturation improved the subtyping of acute myeloid leukemia (AML). A comparison is made here between the MI and the results of surface marker analysis with a panel of monoclonal antibodies (McAb) in the immunofluorescence technique. The McAb applied in 46 AML patients (greater than or equal to 15 years) were granulocyte specific (MI/N1, UJ 308, B4-3, B13-9), granulocyte-monocyte specific (OKM-1, B2-12) or had specificity for the Ia-like antigen (OKI-1), 'T-cells' (3A1), immature cells (OKT-10) or platelets (C17-28). In 32 of these patients more McAb could be investigated with specificities for granulocytes (VIM-D5), granulocytes-monocytes (RUPI-5), monocytes (MONO BRL, RUPI-4), erythrocytes (VIE-G4) and AML cells (VIM-S8). An increase in surface marker expression evident from the reaction with a number of McAb (UJ 308, B2-12, OKM-1 and OKI-1) paralleled the rise of the MI in FAB M5. A decrease of the expression of antigen detected by OKI-1 paralleled the rise of the MI in FAB M1-3. The granulocyte or monocyte specific McAb, as they are determined on normal human peripheral blood cells, did not distinguish between FAB M1-3 and M5. The maturation index seems to be a valuable tool in understanding the results of surface marker analysis.

Autoimmune haemolytic anaemia with monoclonal IgM (kappa) anti-P cold autohaemolysins.

A patient is described with immunoblastic non-Hodgkin's lymphoma and autoimmune haemolytic anaemia of the cold autoantibody type. The autoantibodies were monoclonal IgM-kappa cold haemagglutinins/haemolysins with blood-group specificity, anti-P. Red-cell autoantibodies directed against blood-group-P antigen have until now only been detected, as polyclonal IgG antibodies, in paroxysmal nocturnal haemoglobinuria.

Pseudothrombocytopenia: an immunologic study on platelet antibodies dependent on ethylene diamine tetra-acetate.

Antibodies specifically reacting with platelets only in the presence of EDTA, by the platelet immunofluorescence test, were found in the serum of 20 patients with pseudothrombocytopenia due to in vitro EDTA-dependent platelet agglutination. These antibodies reacted optimally at 0-4 degree C. In 19 patients, IgG antibodies were detected; in 8 patients, IgM or IgA antibodies were also found. In one patient, only IgM antibodies were found. In 14 patients, the IgG antibodies were IgG1, but IgG2, IgG3, and IgG4 antibodies were also seen in 7 patients. The reaction of platelets with the antibodies was detectable in the presence of Na2EDTA, the K, Ca, and Mg salts of EDTA, and K2EGTA. F(ab')2 or F(ab') fragments of the IgG antibodies reached as strongly as the intact antibodies, indicating that the reaction is dependent on the antibody-combining site. The EDTA-dependent antibodies did not show platelet-group specificity. However, platelets from patients with Glanzmann disease did not react with the antibodies.