Treatment of autoimmune thrombocytopenic purpura with rhesus antibodies (anti-Rh0(D)]

There is evidence that blockade of the reticuloendothelial system (RES) by sequestration of autologous red blood cells (RBC) leads to an elevation of platelet counts in immune thrombocytopenia. To substantiate this hypothesis, 10 Rh0(D)-positive adult patients (9 female, 1 male) with chronic autoimmune thrombocytopenic purpura (ITP) (1 to 21 years duration) were treated with low doses of intravenous IgG-anti-Rh0(D) (200 to 1,000 micrograms per dose; 300 to 3,600 micrograms per course; administration within 1 to 5 days). All patients improved clinically as indicated by cessation of bleeding. In eight out of ten patients there was a rise in platelet count. Platelet increments were excellent (greater than 100 X 10(9)/l) in one, good (50-100 X 10(9)/l) in three, fair (20-50 X 10(9)/1) in two and low (10-20 X 10(9)/1) in two patients. Splenectomized patients (N = 4) had a poorer response than non-splenectomized patients (N = 6) with mean increments of 16 X 10(9)/l (range 5-43 X 10(9)/l) versus 60 X 10(9)/l (range 10-110 X 10(9)/l). The increase in platelet counts persisted for seven to over 150 days. Transient and slight signs of haemolysis developed in seven out of ten patients (haemoglobin remained stable; increase of lactate dehydrogenase (greater than 250 IU/l) in four, decrease of haptoglobin (less than 60 mg/dl) in five patients). The direct antiglobulin test became positive in all cases due to IgG1 without complement fixation. We conclude that the interaction of antibody-coated RBC with macrophages (and, probably, other means of RBC alteration) is a feasible therapeutic approach in selected cases of ITP and related conditions.     

The treatment of neonatal isoimmune thrombocytopenia with intravenous immunoglobin (IgG i.v.)

We present a report of the use of IgG i.v. to treat clinically manifest neonatal immune thrombocytopenia. The IgG i.v. was administered at a daily dosage of 0.4 g/kg body weight for 5 days. Treatment was started when the child was 3 days old and had a platelet count of 2 X 10(9)/l. Four days later the platelet count had risen to 200 X 10(9)/l. The diagnosis of immune thrombocytopenia was confirmed by platelet typing of the mother's and child's platelets and identification of anti-platelet antibodies in maternal serum.     

Intravenous immunoglobulin (i.v. IgG) for previously treated acute or for chronic idiopathic thrombocytopenic purpura (ITP) in childhood: a prospective multicenter study

In a prospective multicenter study 42 thrombocytopenic (less than 30 X 10(9) platelets/l) children with chronic idiopathic thrombocytopenic purpura (ITP) or with acute ITP, dependent on or refractory to corticosteroids, were given 0.4 g i.v. IgG/kg body weight/day on 5 consecutive days and thereafter once a week if the platelet count fell to less than 20 X 10(9)/l or if the patient bled. After the initial 5 days of i.v. IgG the platelets rose within a mean of 7-8 days to greater than 30 X 10(9)/l in all and to greater than 150 X 10(9)/l in 33 of 42 patients (79%). After a mean observation time of 26.6 months 26 of 42 patients (62%) showed a satisfactory long-term effect, i.e. no need for treatment for at least 6 months without bleeding and with no platelet counts below 20 X 10(9)/l. No difference in response rate was found between children with chronic and those with previously treated acute ITP. These results indicate that i.v. IgG could be used to control emergency situations, e.g. to stop bleeding or to prepare a patient for surgery. I.v. IgG also represents a good alternative to treatment modalities, such as splenectomy and/or the administration of cytostatic immunosuppressants with potentially serious side effects. In addition to the expected transient rise in serum IgG levels, i.v. IgG induced a more prolonged elevation of serum IgM. Platelet associated IgG, elevated before therapy, was correlated with the clinical long-term outcome.     

The effect of prostaglandins E1, E2, F1 alpha and F2 alpha on pig erythrocytes during haemolysis induced with aspirin and hypotonic NaCl solution

The effect of prostaglandins PGE1, PGE2, PGF1 alpha and PGF2 alpha was investigated on the haemolysis of pig erythrocytes induced with aspirin and hypotonic (0.119 M) NaCl solution. An inhibiting effect was observed of low concentrations (2 X 10(-5) M, 2 X 10(-4) M and 2 X 10(-3) M) of aspirin on haemolysis induced with hypotonic NaCl solution, while in a concentration of 2 X 10(-2) M aspirin itself caused haemolysis which amounted to 93% of the haemolysis induced with 0.041 M NaCl solution. No differences were observed in the degree of haemolysis inhibition in relation to the time of incubation of erythrocytes with aspirin. Aspirin concentrations from 0.035 M to 0.280 M caused slight haemolysis (9-15% of the haemolysis induced with water), the 0.560 M solution caused haemolysis corresponding to 85% of the water-induced haemolysis. None of the studied prostaglandins used in concentrations of 0.4 X 10(-3) M, 0.4 X 10(-4) M and 0.4 X 10(-5) M had any significant effect on aspirin-induced haemolysis. PGE1 and PGE2 in concentrations of 0.4 X 10(-3) M, 0.4 X 10(-4) M and 0.4 X 10(-5) M inhibited haemolysis induced with 0.119 M sodium chloride solution, and the degree of haemolysis inhibition was from 8% to 35%. Prostaglandins PGF1 alpha and PGF2 alpha in the same concentrations had no protective effect.     

Monoclonal antibody for calcitriol (1 alpha,25-dihydroxyvitamin D3)

Hybridoma cell lines secreting antibodies for vitamin D3 metabolites have been generated by fusing splenocytes from BALB/c mice immunized with 3 beta-glutaryl-25-hydroxyvitamin D3 conjugated to bovine serum albumin (3 beta-glu-25-OH-D3-BSA) and Sp2/O-Ag14 myeloma cells. Purification of monoclonal antibodies from culture media or ascites fluids was accomplished by procedures including affinity chromatography on Protein A-Sepharose 4B. Each monoclonal antibody was analyzed as to its affinity and specificity by equilibrium dialysis and an enzyme immunoassay (EIA) based on a double antibody system. It was demonstrated that clone 1C2-60 produced an antibody highly specific to 1 alpha,25-dihydroxyvitamin D3 (calcitriol), and the clone 2B3-66 antibody was reactive to 25-hydroxyvitamin D3 and similar structural compounds. These two monoclonal antibodies produced by 1C2-60 and 2B3-66 were determined to belong to the IgG2a class, and their affinity constants (Ka) with 3 beta-glu-25-OH-D3 were demonstrated to be 3.6 X 10(9) M-1 and 2.9 X 10(9) M-1, respectively, at 4 degrees C. The characteristics of these monoclonal antibodies were compared with those of conventional antibodies raised in mice and rabbits. Finally, by using monoclonal antibody 1C2-60, a sensitive EIA has been developed that can detect 10 pg of calcitriol.     

Characterization of binding of four monoclonal antibodies to the human ovarian adenocarcinoma cell line HEY

Four mouse monoclonal antibodies (mAb) (10B, IgG1; 8C, IgG2a; M2A, IgG2a; M2D, IgG2b) were characterized with respect to their binding to the ovarian adenocarcinoma cell line HEY, using displacement assays and Scatchard plot analyses. The four mAb reacted with different antigens on the surface of HEY cells, with affinity constants ranging from 1 X 10(9) to 3 X 10(9) M-1. The number of binding sites per cell for each antibody was approximately 2 X 10(4). mAb 8C and M2D remained associated with the cell surface following binding to their respective antigens, while mAb 10B was rapidly internalized, with 50% of the bound mAb being lost from the cell surface during 4 h of incubation at 37 degrees C. These different binding characteristics of the mAb may influence their ability to target radioactivity and cytotoxic drugs to HEY cells.     

Studies of the mechanism of bacterial resistance to complement-mediated killing. V. IgG and F(ab')2 mediate killing of E. coli 0111B4 by the alternative complement pathway without increasing C5b-9 deposition

The mechanism of antibody-dependent complement-(C) mediated killing of Escherichia coli 0111B4, strain 12015 (12015), was examined. 12015 was resistant to serum killing when incubated in hypogammaglobulinemic serum (H gamma S) or pooled normal human serum (NHS) that had been previously adsorbed to remove specific antibody (Abs NHS). Presensitization with immune rabbit serum or purified immune rabbit IgG resulted in 1 to 3 log killing when 5 X 10(8) colony forming units (CFU)/ml were incubated in 10 to 40% Abs NHS. Binding of 125I-C3 and 131I-C9 to the bacterial surface of the presensitized and the nonpresensitized strain was quantitated when these organisms were incubated in 10, 20, and 40% Abs NHS. Stable binding of up to 3.0 X 10(5) molecules of C3 and 8.0 X 10(4) molecules of C9 to presensitized and nonpresensitized isolates occurred in the highest concentration of serum, but there was no killing without presensitization. Similar results were found when Abs NHS was chelated with ethylene bis glycoltetraacetic acid containing 2 mM MgCl2 (Mg EGTA) to block classical pathway activation, indicating that antibody mediated the bactericidal reaction through the alternative pathway. Deposition of C3 and C9 and killing of 120 15 in 10% Abs NHS or 10% H gamma S was measured after presensitization with increasing amounts of IgG, F(ab')2, or Fab'. There was a dose-dependent increase in C3 deposition and killing, but only minimal change in C9 binding when 1.0 X 10(3) to 3.2 X 10(4) IgG or F(ab')2/CFU were bound to the bacterial surface. In contrast, there was no increase in C3 or C9 binding and no bacterial killing when 1 X 10(3) to 3.4 X 10(4) molecules Fab'/CFU were bound to the bacterial surface. These experiments show that immune IgG and F(ab')2 can mediate killing of E. Coli 0111B4 by the alternative pathway without changing the extent of terminal C component attachment to the bacterial surface.     

重组人红细胞生成素单克隆抗体的制备

本文应用常规淋巴细胞杂交瘤技术制备了4株能稳定分泌抗人重组红细胞生成素(rHuEPO)单克隆抗体(McAb)的小鼠杂交瘤细胞系:BⅡ1B5、DⅡ6B9、MⅡ1H4、GⅠ3E7,用鼠单克隆抗体分型试剂盒鉴定,其分泌的McAb的类型分别是:IgM、IgM、IgG1和IgG2a。间接ELISA法测定细胞上清的效价为1×10~(-2)～1.25×10~(-1),腹水效价为1×10~(?)～1×10~(?)。培养上清经ELISA鉴定,与IL-2、GM-CSF、IFN-α等细胞因子均无交叉反应。只与rHuEPO特异性结合。     

Analysis of the interaction of antibodies with immunoglobulin idiotypes on neoplastic B lymphocytes: implications for immunotherapy

We have examined the reactions of a panel of nine monoclonal anti-idiotype antibodies with the surface immunoglobulin in situ on guinea pig L2C leukemic lymphocytes. Equilibrium binding constants were shown to range between 10(7) and 10(8) M-1 for univalent Fab' gamma fragments and between 10(8) and 10(9) M-1 for intact IgG. Saturation of the cell surface binding sites was achieved with 2.9 X 10(5) Fab' gamma molecules/cell and 1.2 X 10(5) IgG molecules/cell for each antibody, a result that is consistent with a bivalent mode of interaction for the IgG. Despite these overall similarities in binding characteristics antibodies showed striking differences in their ability to clear Ig from the cell surface by antigenic modulation in vitro. This suggested differences in the readiness with which the antibodies cross-linked neighboring surface Ig molecules. Such an interpretation was supported by differences in the times required to achieve bivalent binding at 0 degree C, and in the rates at which labeled antibody dissociated from the cell surface in the presence or absence of an excess of unlabeled antibody. The data are consistent with there being two functionally distinct types of anti-idiotype antibody: those that form predominantly intra-Ig bridges, with each antibody Fab being linked to an Fab on one target molecule ("monogamous" binding) and not favoring modulation; and those that form predominantly inter-Ig bridges ("bigamous" binding) and favor modulation. The nature of interaction is presumably dictated by the orientation of the particular idiotope concerned. This distinction could be of great importance in the therapeutic use of anti-idiotype to ablate B cell neoplasms.     

Characterisation of monoclonal antibodies raised against testosterone

Using the antigens testosterone-17 beta-hemisuccinate and testosterone-3-(o-carboxymethyl) oxime, each coupled to bovine serum albumin, we have produced 44 monoclonal antibodies to testosterone. Of the 17 monoclonal antibodies raised against the 17 beta-linked antigen 8 showed extremely low affinity for testosterone (Ka less than or equal to 8 X 10(7) M-1) and none had an affinity greater than 5 X 10(9) M-1. Of the 27 monoclonal antibodies raised against the 3-linked antigen 2 had affinities less than 8 X 10(7) M, 7 had affinities greater than 5 X 10(9) M-1 and one had an affinity (Ka = 9 X 10(10) M-1) greater than that of a high affinity rabbit antiserum (Ka = 6 X 10(10) M-1). The affinity constant (Ka = 5 X 10(9) M-1) measured in the serum of the mouse whose spleen gave rise to the greatest number of high affinity antibodies, was significantly higher than those measured in the sera of the remaining mice (Ka = 0.7 - 3 X 10(8) M-1). The cross-reactions of the monoclonal antibodies varied widely but none showed an overall improvement in specificity when compared with the corresponding rabbit antisera. Results suggest that as well as the structure of the steroid antigen careful selection of the spleen donor facilitates the development of monoclonal antibodies with good binding characteristics.     

Clinical effect and some pathogenic mechanisms of high dose monomeric IgG therapy in childhood chronic idiopathic thrombocytopenic purpura

8 children with chronic idiopathic thrombocytopenic purpura received a high dose therapy with monomeric IgG. Before and after the treatment immunological investigations were carried out. All the children showed a positive clinical response, in 5 children there was an increase of thrombocytes to 111-340 X 10(9)/l. A clinico-haematological effect could be shown in those children with an increased percentage of marrow megakaryocytes with IgG fixed on the membrane before treatment. There was no haematological effect neither in cases with fixed IgG and IgA nor IgM and IgA combined, as well as in the case when there was no fixed IgG on the membrane. A steady clinical effect was provided if the number of bone marrow megakaryocytes with fixed IgG reached the norm. The suppression of the synthesis of antithrombocytic antibodies of the same immunoglobulin class can be regarded as a specific mechanism of high IgG doses.     

Fractionation of polyclonal antibody by isoelectric focusing--differences in cross-reactivity and affinity of rabbit clonotype anti-human thyrotropin antibody

Immunoglobulin G (IgG) fractions prepared from three different batches of rabbit antihuman thyrotropin (hTSH) antisera were fractionated by agarose isoelectric focusing (IEF) in the pH ranges 3 to 10 and 5 to 8. Staining of protein in agarose gel after IEF showed that polyclonal IgG separated into more than 20 protein bands with isoelectric points (pIs) ranging from 6 to 9. The clonotype antibodies to hTSH were recovered from the fractions and subjected to radioimmunoassay for determination of the binding-affinity for hTSH and the cross-reactivity with human chorionic gonadotropin (hCG). The affinity constants of the antibodies recovered ranged from 6.4 X 10(9) M-1 to 3.1 X 10(10) M-1, and the cross-reactivities of the clonotype antibodies differed greatly. A good correlation was observed between the pIs of antibody molecules and their cross-reactivities: antibodies with higher pIs bound hCG more strongly than those with lower pIs. The correlation coefficients between the pIs and cross-reactivities were 0.83, 0.84, and 0.87 in three batches of antibody.     

Characterization of monoclonal antibodies to the beta-adrenergic antagonist alprenolol as models of the receptor binding site

Antibodies to receptor ligands have been valuable in understanding the nature of receptor-ligand interactions. We have developed four monoclonal antibodies to the beta-adrenergic receptor antagonist alprenolol by immunizing A/J mice with (-)-alprenolol coupled to keyhole limpet hemocyanin. The antisera from these mice displayed specific [3H]dihydroalprenolol ([3H]DHA) binding that was inhibited by alprenolol, propranolol, and isoproterenol. Somatic cell fusion of spleen cells from the immunized mice to SP2/0 myeloma cells, followed by limited dilution subcloning, resulted in the isolation of four hybridomas (1B7, 5B7, 5D9, and 2G9) demonstrating three different classes of ligand binding characteristics. 1B7 had the highest binding affinity for antagonists based on Scatchard analysis (Kd [125I]- CYP = 1.4 X 10(-10) M; Kd [3H]DHA = 6.5 X 10(-9) M), and was the only antibody to demonstrate agonist-inhibition of [3H]DHA binding. Ki values computed from competitive inhibition curves of [3H]DHA binding to 1B7 resulted in a rank order of potency similar to that of beta-2-adrenergic receptors: (-)-propranolol greater than acebutolol amine greater than isoproterenol greater than (+)-propranolol greater than epinephrine greater than norepinephrine. 5B7 and 5D9 exemplified a second class of antibody. This pair had lower antagonist binding affinities (Kd [3H]DHA = 2 X 10(-8) M and 2.5 X 10(-7) M, respectively) and was stereoselective in binding receptor antagonists: (-)-propranolol greater than (+)-propranolol greater than acebutolol amine. Agonist inhibition of [3H]DHA binding to these antibodies could only be observed at very high concentrations (greater than 10(-4) M agonist), and was not dose-dependent. Finally, the class of anti-alprenolol monoclonal antibodies represented by 2G9 had the lowest antagonist binding affinity of all (IC50 alprenolol = 1 X 10(-5) M), did not demonstrate ligand stereoselectivity, and did not recognize agonists. We propose that antibodies raised against beta-adrenergic receptor ligands demonstrating stereoselective agonist binding will also demonstrate high affinity antagonist binding, and that they will closely parallel the binding characteristics of the receptor. According to this "agonist best-fit hypothesis," anti-idiotypic antibodies raised against the binding site of these idiotypes might contain true mirror images of the beta-adrenergic receptor binding site.     

Conformation-specific monoclonal antibodies to the calcium-induced structure of protein C

Monoclonal antibodies to various domains of human protein C were characterized, and the cross-reactivity of these antibodies with other vitamin K-dependent proteins was explored. Three antibodies, JTC-1, -2, and -3 reacted with protein C only in the presence of Ca2+ and were shown to bind to the light chain of protein C. It is suggested that these antibodies recognize a gamma-carboxyglutamic acid domain-related conformational change induced by metal ions, evidenced by the fact that half-maximal binding was observed at calcium concentration of 0.5, 0.6, and 0.7 mM, respectively, by the fact that these antibodies, even in the presence of Ca2+, do not react with gamma-carboxyglutamic acid domainless protein C, and by the fact that Zn2+ and Tb3+ support binding in essentially the same way. Each cell line was stabilized by recloning five times. In addition each antibody had a single isoelectric point and was of the IgG1 kappa class. The interaction of antibodies JTC-1, -2; and -3 with protein C-Ca2+ was characterized by a single class of binding sites with Kd of 3.98 X 10(-9) M, 4.01 X 10(-9) M, and 6.76 X 10(-9) M, respectively. However, antibodies JTC-1, -2, and -3 bound to prothrombin-Ca2+ with Kd of 7.81 X 10(-9) M, 2.0 X 10(-7) M, and higher than 1.0 X 10(-5) M, respectively. In addition they had weak affinity for factor X in the presence of Ca2+. The results indicate that the antibodies JTC-1, -2, and -3 are conformation-specific monoclonal antibodies directed against an at least partially common metal ion-induced three-dimensional structure in protein C, prothrombin, and factor X.     

The comparison of gammaglobulin to steroids in treating adult immune thrombocytopenia. An interim analysis

Symptomatic immune thrombocytopenia is a life-threatening situation which is conventionally treated in the adult with prednisone, although subsequent splenectomy is frequently unavoidable. Recently, high-dose intravenous gamma-globulin has been reported to be an effective alternative option, particularly in children. To determine the role of this agent in adults a controlled prospective trial has been undertaken. Previously untreated patients with immune thrombocytopenia were randomised to compare oral prednisone (1 mg/kg/day: Group 1: n = 13) to high-dose intravenous gamma-globulin (400 mg/kg on days 1 through 5: Group 2: n = 7), or a combination of both agents given on the same schedule (Group 3: n = 12). The time from diagnosis to commencement of treatment, initial platelet counts, age and sex were comparable in the three groups. At this interim analysis there has been no mortality, but one patient has suffered a cerebrovascular accident. Objective response, defined as a platelet count greater than 50 x 10(9)/l, was achieved in a median of 5, 5 and 3 days, whereas the time taken to reach peak counts were 9, 5 and 7 days, respectively. The relapse rates, percentage of patients subsequently requiring splenectomy for control of symptomatic bleeding and the postoperative course was comparable between the three groups. These data, although preliminary, re-emphasize differences between the paediatric and adult forms of immune thrombocytopenia and also suggest in the latter patients a need for caution before advocating replacement of prednisone by gammaglobulin as the primary form of treatment.     

Neonatal autoimmune thrombocytopenia: role of high-dose intravenous immunoglobulin G therapy

High-dose intravenous immunoglobulin G (IVIgG) therapy results in a rapid reversal of thrombocytopenia in over 80% of children with acute immune thrombocytopenic purpura (ITP). Comparable results were observed in eleven infants with an analogous condition, neonatal autoimmune thrombocytopenia (NATP), who received IVIgG (2 g/kg body weight) administered alone (n = 6) or in combination with steroids (n = 5). The median platelet count pre-IVIgG therapy was 25 X 10(9)/l (range 5 to 74 X 10(9)/l). The overall response rate to IVIgG therapy, administered alone or in combination with steroids was 75% (12 of 16 treatment episodes). A good response to therapy was defined as an increase in the platelet count to greater than or equal to 50 X 10(9)/l and at least twice the pre-treatment value at 48 h after completion of the IVIgG infusion. The rapid and generally excellent response to IVIgG therapy in infants with NATP suggests that this treatment approach should be considered as first-line therapy for severely thrombocytopenic infants with this self-limiting but potentially serious disorder.     

Shortening of bleeding time after intranasal administration of 1-deamino-8-D-arginine vasopressin to patients with chronic uremia

1-deamino-8-D-arginine vasopressin (DDAVP) was administered intranasally in a dose of 2 micrograms/kg BW to 17 uremic patients (16 maintained on chronic hemodialysis and 1 treated conservatively). The bleeding time was significantly shortened 120 minutes after DDAVP administration (from 18.1 +/- 7.5 minutes to 12.3 +/- 6.4 minutes p less than 0.001). Factor VIII related antigen (VIII: Ag) did not change. Factor VIII ristocetin cofactor activity (VIII: RCof) significantly increased (from 251.2 +/- 162.0 to 336.5 +/- 167.2 p less than 0.025). Platelet count decreased significantly after DDAVP (from 174.9 +/- 43.8 X 10(9)/l to 155.6 +/- 45.9 X 10(9)/l 30 minutes p less than 0.01 and 129.8 +/- 45.2 X 10(9)/l p less than 0.005 120 minutes after DDAVP). Antithrombin III concentration, and hematocrit did not change. Our data indicate that further clinical studies of intranasal DDAVP in uremic patients during episodes of bleeding are warranted.     

Recognition of two Dermatophagoides pteronyssinus-specific epitopes on antigen P1 by using monoclonal antibodies: binding to each epitope can be inhibited by serum from dust mite-allergic patients

Monoclonal antibodies were raised against Antigen P1, the major allergen of the house dust mite (Dermatophagoides pteronyssinus). The majority were Antigen P1 specific, isotype IgG1, and did not react with a comparable D. farinae allergen. These antibodies bound 38 to 50% of 125I Antigen P1 in antigen-binding assays (titer greater than or equal to 1/1,000,000), and the quantities of IgG antibody in ascites were 2 to 4 logs greater than those in polyclonal mouse antiserum or in serum from a mite-allergic patient. Two IgM antibodies showed weak binding to Antigen P1 but reacted strongly with D. pteronyssinus in enzyme immunoassay (titer greater than or equal to 1/100,000). Assessments of the specificity of the IgG antibodies by using two inhibition radioimmunoassays suggested that they were directed against two different epitopes. Antibodies 10B9 F6 and 5H8 C12 were purified by preparative isoelectric focusing (isoelectric points of pI 6.25 and 7.4, respectively) and radiolabeled with 125I. Cross-inhibition experiments, using ascites dilutions to inhibit binding of each radiolabeled antibody to Antigen P1, confirmed that these antibodies recognized two distinct epitopes. Analysis of antibodies from 39 clones/hybrids showed that the majority were directed against the same epitopes as either 10B9 F6 or 5H8 C12 (3 out of 39 [8%] and 29 out of 39 [74%], respectively). None of the monoclonal antibodies significantly inhibited (greater than 10%) human IgE binding to Antigen P1 in the radioallergosorbent test. However, 12 of 14 sera from mite allergic patients inhibited binding by the monoclonal antibodies. One serum from a mite-allergic patient inhibited binding of both 10B9 F6 and 5H8 C12 by greater than 85% and showed parallel inhibition curves. The results suggest that these monoclonal antibodies could be used to assay Antigen P1 in both D. pteronyssinus and house dust extracts. It should also be possible to use monoclonal antibodies in inhibition assays to define the antigenic/allergenic determinants recognized by human IgG and IgE antibodies on this mite allergen.     

Generation of monoclonal antibodies to Macaca mulatta (rhesus) IgA

One IgG1 and five IgM murine monoclonal antibodies (mAb) specific for rhesus (Rh) IgA were generated. These mAbs bound to Rh IgA but not IgG or IgM when tested by enzyme-linked immunosorbent assay. Immunoblotting revealed that the mAbs reacted with the alpha heavy chain of Rh but not human IgA. The IgG1 anti-Rh IgA mAb detected IgA-producing cells in sections of monkey gut examined by immunofluorescent staining. These mAbs should be useful for characterizing IgA responses in the Rh monkey.     

Recombinant interferon-alpha, but not interferon-gamma is effective therapy for essential thrombocythemia

Recombinant interferon-gamma with a starting dose of 0.5 mg 3x/week subcutaneously, was administered to 6 patients with essential thrombocythemia (median platelet count 1172 X 10(9)/l, range 602-1564). Four of the patients had received alkylating agents previously. Hematological remission, defined as a decrease in platelet counts to less than or equal to 350 X 10(9)/l, was observed in none of these patients. Subsequently 4 of these 6 patients, supplemented by 2 others were treated with interferon-alpha 2c at a dose of 5 X 10(6) U daily subcutaneously. Five patients showed hematological remission. In case of hematological remission the interferon-alpha doses was reduced to 5 X an thereafter to 3 X weekly 5 X 10(6) U. During an observation period ranging from 12-41 weeks platelet counts remained normal in all patients. Side-effects were mild and consisted of fever, myalgias, malaise and itching occurring mainly during the first month of treatment. No dose adaptation was required. The patients treated previously with interferon-gamma experienced the side effects from this drug less tolerably than those from the alpha-compound. These observations suggest that recombinant interferon-alpha may be an effective drug in treating essential thrombocythemia resulting in a sustained response.