Quantitative monitoring of WT1 expression in peripheral blood before and after allogeneic stem cell transplantation for acute myeloid leukemia - a useful tool for early detection of minimal residual disease

Overexpressed Wilms tumor gene 1 (WT1) has been found in a majority of patients with acute myeloid leukemia (AML). The aim of this study was to confirm the applicability of WT1 expression measurement as a marker of minimal residual disease (MRD). The expression of WT1 gene was measured by real-time polymerase chain reaction in peripheral blood (PB) according to European Leukemia Net (ELN) recommendations. The WT1 expression was related to the expression of a reference gene Abelson (ABL) and the results were calculated as a number of WT1 copies related to 104 copies of ABL gene. The upper normal limit of WT1 expression was set at 50 copies of WT1 to 104 copies of ABL. Morphological, flow cytometry and chimerism examinations were evaluated according to standard protocols.A total of 51 AML patients with overexpressed WT1 gene were analyzed. The median follow-up after transplantation was 14 (2-72) months. WT1 expression levels exceeding the upper normal limit were considered as a sign of impending hematological relapse, in accord with morphological, flow cytometry and chimerism data, as well as with the expression of the specific fusion genes. Moreover, in 7 patients the rise of WT1 expression preceded all other standard methods. Patients with high WT1 expression before allogeneic hematopoietic stem cell transplantation (allo-HSCT) had significantly worse outcome than patients with low WT1 level. Examination of WT1 expression in PB of patients with AML is a useful tool for MRD monitoring. Moreover, the WT1 gene expression before stem cell transplantation seems to be of prognostic significance.

[Frequency view on genome changes testing]

Laboratories dealing with human genome, both inherited and acquired changes, dispose with similar methods and technology. The spectrum of genetic tests is relatively broad and the number of mutations or variants tested differs substantially. Also the number of examinations carried out in individual laboratories varies. Data presented in the tables come from the year 2004 and indicate the number of examinations requested and number of positive results. Many laboratories mentioned in the registry CZDDNAL (http://www.uhkt.cz/lab_a_vysetreni/nr lab_dna_diag/dna_lab_db) perform the same tests but there is also a great number of tests carried out by only one laboratory. Reasons of the request, cost-effectiveness and clinical utility of genetic testing is being discussed.

[The use of quantitative assessment of Wilms tumour gene 1 for monitoring of residual disease in acute myeloid leukemia patients]

BACKGROUND

Despite a considerable effort, the majority of acute myeloid leukaemia (AML) patients do not have a suitable specific molecular marker for monitoring minimal residual disease (MRD). The results of some studies suggest the Wilms tumour gene (WT1) as a possible molecular marker of MRD.

METHODS AND RESULTS

We measured the expression of WT1 at diagnosis and during treatment of the acute myeloid leukaemia (AML) patients. The expression of WT1 was measured by the quantitative real-time RT-PCR in peripheral leukocytes from 56 AML at diagnosis and 7 patients with AML transformed from myelodysplastic syndromes (MDS). The WT1 expression was significantly elevated (up to 3 orders of magnitude) in peripheral blood samples (PB) of AML patients at diagnosis compared to PB samples of healthy donors (P < 0.0001). The level of WT1 expression depends particularly on FAB AML subtype, with the highest being found in AML patients with subtypes M4, M1, M3 and AML transformed from MDS. Conversely, AML patients with M2 and with the presence of AML1/ET0 at presentation showed a significantly lower expression of the WT1 gene compared to the remaining AML patients at presentation (P = 0,005). Further, sequence samples of 12 AML patients under long-term surveillance were tested for the WT1 expression in parallel with the expression of specific MRD markers--fusion genes: AMLI/ETO, PML/RARalpha and CBFB/MYH11. The levels of WT1 gene expression and the above specific fusion genes significantly correlated. Moreover, 14 patients without the specific MRD marker were tested for the WT1 expression. The results show that haematological relapses were associated with the rise of expression of the specific fusion genes and with the WT1 gene expression. The rise of WT1 expression above the level seen in leucocytes from peripheral blood and/or bone marrow of healthy donors--in four patients under long-term surveillance the "molecular relapse" predicted ongoing haematological relapses as early as 2 months in advance.

CONCLUSIONS

Our results, in accordance with some of the previously published ones, show that WT1 expression seems to be a suitable marker of minimal residual disease in AML patients.

Immunological profiles of patients with chronic myeloid leukaemia. I. State before the start of treatment

In view of the increasing interest in the immunotherapy of CML it seems highly desirable to broaden the present knowledge on the immune reactivity of CML patients. A group of 24 patients and 24 healthy controls were studied for the total of 15 immunological parameters, including the prevalence of antibodies against human herpesviruses and papillomaviruses. To clearly discriminate between changes associated with the disease and those induced by the therapy, all patients were enrolled prior to the start of any anti-leukaemic therapy. Statistically significant differences between patients and controls were found in the levels of IgA, C4 component of complement, CRP and IL-6, the production of Th1 cytokines in stimulated CD3 cells and the E. coli stimulatory index. The analysis of the interrelationship between the results obtained in the individual patients presented some unexpected findings, such as the lack of correlation between the CRP and IL-6 levels. It will be the purpose of a follow-up to determine whether and how the immune status of the patients prior to the treatment correlates with their response to therapy and how the individual immunological profiles change in the course of the disease. These observations will be utilized in the future immunotherapeutic studies to constitute the vaccine- and placebo-treated groups.

Gene expression during camptothecin-induced apoptosis in human myeloid leukemia cell line ML-2

Malignant cell proliferation and accumulation depends on the balance between the rates of cell production and cell death. Recent evidence indicates that apoptosis is important in the development of cancer. Apoptosis is strictly controlled by various regulators, which can take part in the apoptotic process, proliferation and differentiation alike. Apoptosis was induced in myeloid cell line ML-2 by camptothecin, an inhibitor of topoisomerase I. After 18 hours of induction by camptothecin 50% of cells were apoptotic. The apoptotic effect of CAM was reversible in the cells studied. The induction of apoptosis influenced the expression of apoptosis and cell cycle regulators as detected by cDNA arrays, RT-PCR or Western blotting. According to cDNA arrays e.g. bax, bfl1, bak, pRb2, c-jun, jun-B were upregulated, and cdk4, cyclin B1, wee1, CRAF1, DP1 were downregulated. A number of other regulators like p21 and cdc25A, as well as some other genes linked with apoptosis, as p53 and the bcl-2 family, were up- or down-regulated as determined by real-time PCR. Changes in gene expression were found not only in the group of regulators of apoptosis and the cell cycle, but also among regulators of differentiation.

[Expression of cyclin-dependent kinase inhibitors in leukemia]

BACKGROUND

Leukemias develop due to defects in proliferation, differentiation and apoptosis, which take place in stem cells or progenitors of hematopoiesis. These processes have several crossing points, one of them is the role of inhibitors of cyclin-dependent kinases. The aim of this study was to study the expression of cyclin-dependent kinases inhibitors p21 Cip and p27 Kip and expression of proliferative antigen Ki-67 in leukocytes of human leukemia.

METHODS AND RESULTS

The expression of cyclin-dependent kinases inhibitors was detected at mRNA level mainly by comparative reverse-transcription polymerase chain reaction and in selected samples also by the real-time polymerase chain reaction. While p27 Kip expression in leukocytes of leukemic patients and healthy persons was universal, large differences in expression of p21 Cip were found both among individual patients of the same type of leukemia and between different types of leukemias and healthy persons. The p21 Cip expression was significantly higher in acute leukemias than in chronic ones and healthy persons. A comparison of p21 Cip expression with the clinical outcome of the leukemic patients showed that the group of 14 acute leukemia patients surviving more than 30 months had a significantly lower expression of p21 Cip than 12 patients of this type of leukemia who died within this time limit. Moreover, the results obtained on a smaller set of acute promyelocytic leukemia patients indicated that the lower p21 expression is connected with a better prognosis.

CONCLUSION

Our results pointed out the importance of the cyclin-dependent kinase inhibitor p21 Cip in human leukemias and indicated that the lower p21 Cip expression might be a positive prognostic factor in acute myeloid leukemia patients.

The use of housekeeping genes (HKG) as an internal control for the detection of gene expression by quantitative real-time RT-PCR

Quantitative real-time RT-PCR is a very useful technique for estimating gene expression at the mRNA level. The expression of a tested gene has to be compared with that of a control gene. Various housekeeping genes have been used as control genes in different systems. In our study we tested several housekeeping genes in the model of gene expression after induction of apoptosis and differentiation. The myeloid cell lines were incubated with phorbol esters, butyric acid and combination of TNFalpha and IFNgamma to induce differentiation. Camptothecin was used for induction of apoptosis. Tested control genes included beta2-microglobulin, GAPDH, 18S ribosomal RNA and abl. GAPDH was found to be the best control gene in the apoptotic system. Different control genes were suitable for different systems where differentiation or senescence was induced. Our results show that attention should be paid to the choice of an appropriate control gene of quantitative real-time RT-PCR for different experimental models and various experimental conditions.

Location of the BCR/ABL fusion genes on both chromosomes 9q34 in Ph negative chronic myeloid leukemia

We present two patients with Ph-negative chronic myeloid leukemia (CML) and fusion signal BCR/ABL on both chromosomes 9, located in region 9q34. The first case was a 27 years old man with CML. Molecular studies (RT-PCR) revealed the rearrangement in the major-BCR region and expression of chimeric BCR/ABL mRNA of b3a2 configuration. By classical cytogenetic studies (G-banding) karyotype 46,XY was found in short-term cultivated bone marrow cells and phytohemagglutinin (PHA) stimulated peripheral lymphocytes. FISH studies revealed the BCR/ABL fusion signals on both chromosomes 9 and green BCR signals on both chromosomes 22 in all mitoses studied. Detection of the alleles of ABL1 intragenic STR locus by fluorescence PCR followed by fragmentation analysis in the patient and his parents provided no information about transmission of the ABL gene. Quantitative assessment of BCR/ABL transcript level by RT-PCR showed 60 and 70% BCR/ABL positivity in two peripheral blood samples at 6,5 and 10,5 months after diagnosis, respectively, which does not correspond to the expression from two identical BCR/ABL hybrid genes. Therefore, the possible mechanism of the origin of two BCR/ABL fusion signals present on both chromosomes 9 could not be resolved and remains speculative. The second case was a 53 years old male with diagnosis of chronic phase of CML, with first sign of acceleration one month after diagnosis and death because of sepsis in blastic phase within four months. The cytogenetic findings were identical to those in case No. 1., i.e. karyotype 46, XY by G-banding, two BCR/ABL fusion signals on both chromosomes 9 and RT-PCR molecular studies proved b3a2 breakpoints. It is generally accepted that prognosis of the patients with fused BCR/ABL gene located on chromosome 9 is poor. The presence of two fused genes could be anticipated as two Ph chromosomes in accelerated and blastic phases of the disease. However, in our study, quantitative findings of BCR/ABL transcripts did not corresponded to the expression of two BCR/ABL genes originating from duplication. If this assumption is correct then the expression of both fused genes BCR/ABL was in case No. 1 equally suppressed and total expression reached about the level of one BCR/ABL gene.

Aleukemic granulocytic sarcoma with AML1/ETO fusion gene expression and clonal T cell populations

We report a unique case of aleukemic granulocytic sarcoma of the neck, originally misdiagnosed as non-Hodgkin's lymphoma (NHL), though chloroma was also suspected due to a greenish macroscopic appearance and the presence of myeloid chloroacetate esterase (CAE)+ cells. The proof of clonal T cell receptor gamma chain (TcRgamma) gene rearrangements in the recurring tumor was deemed to confirm the initial diagnosis of T cell NHL. Altogether five distinct types of clonal TcRgamma gene rearrangements were found in the tumor, bone marrow and peripheral blood. Only retrospectively, using RT-PCR, did we detect the acute myeloid leukemia subset-specific fusion gene AML1/ETO in the frozen samples of the relapsed tumor, as well as in the otherwise unaffected bone marrow and peripheral blood (representing 'minimal initial disease' in the latter two samples). Simultaneous staining verified that the neoplastic CAE+ cells and CD45RO+ T cells were different populations.

[Detection of BCR/ABL, MLL/AF4 and TEL/AML1 hybrid genes and monitoring of minimal residual disease in pediatric patients with acute lymphoblastic leukemia]

BACKGROUND

The BCR/ABL and MLL/AF4 fusion genes--resulting from t(9;22)(q34;q11) and t(4;11)(q21;q23) translocations, respectively--are considered as a high risk prognostic factors in children with acute lymphoblastic leukaemia (ALL). Their presence in malignant cells indicates patient for the most intensive antileukaemic therapy regardless of the other criteria. In contrast, the most common non-random chromosomal aberration in paediatric ALL--translocation t(12;21)(q12;q22)--is associated with a favourable prognosis. The examination of these rearrangements is important for the stratification of patients to the risk groups and also provides the most sensitive and specific tool for minimal residual disease (MRD) follow-up.

METHODS AND RESULTS

This study comprises 241 patients with ALL from Czech and Slovak Republics younger than 18 years at diagnosis. They were examined for presence of m-RNA of fusion genes BCR/ABL, MLL/AF4 and TEL/AML1 by reverse transcriptase-polymerase chain reaction (RT-PCR) method. Seven out of 197 (3.6%) carried MLL/AF4 fusion gene, but among infants it was 56% (5 out of 9). BCR/ABL positivity was found in 2.5% (7 out of 240) and TEL/AML1 in 21.7% (41 out of 189) cases. Event free survival (EFS) curves demonstrate the clinical impact of these hybrid genes on patients' prognosis. Moreover, we present the possibility of the monitoring of MRD levels in follow-up samples of these patients.

CONCLUSIONS

All particular rearrangements were found only in a cohort of patients with B-precursor ALL (or hybrid leukaemia), which constitutes 85% of our group. Presence of BCR/ABL or MLL/AF4 fusion gene is associated with poor prognosis and is indispensable condition for correct stratification of patients to the risk groups according to treatment protocols. Hybrid gene TEL/AML1 defines subgroup of children with better prognosis and due to its high frequency provides us with a very useful tool for MRD detection.

P230 BCR/ABL protein may be associated with an acute leukaemia phenotype

The BCR/ABL rearrangement, the molecular hallmark of chronic myelogenous leukaemia (CML), is rare in acute myeloid leukaemia (AML), being detected in approximately 1% of cases. In the vast majority of CML cases the breakpoint on chromosome 22 falls in the so-called major breakpoint cluster region of the BCR gene. Only a few cases of CML with breakpoint in the minor or in the micro bcr region have so far been reported. The micro breakpoint position has been associated mainly with a mild form of CML, defined as Philadelphia chromosome-positive chronic neutrophilic leukaemia (Ph-positive CNL). Using reverse transcription-polymerase chain reaction (RT-PCR) we report a patient with an acute myeloid leukaemia phenotype at diagnosis who showed a BCR/ABL rearrangement with a breakpoint located in the micro bcr region (e19a2 junction). Cytogenetic analysis showed a progression of the malignant clone, finally leading to cells with two Ph chromosomes, trisomy 8, isochromosome 17q and deletion of the long arms of chromosome 7. The findings of chromosomal changes point to a possibility of blast crisis of CML with a clinically silent chronic phase. Immunoprecipitation and auto-phosphorylation assay revealed the expression, by the patient's blast cells, of an abnormal P230 BCR/ABL protein, which showed for the first time that this protein was constitutively activated in primary cells from patients. This finding may contribute to the understanding of the role of the BCR/ABL rearrangements in determining different leukaemia phenotypes ranging from acute lymphoid and myeloid leukaemias to mild chronic neutrophilic leukaemias.

Simple competitive two-step RT-PCR assay to monitor minimal residual disease in CML patients after bone marrow transplantation

Quantitative reverse transcription-polymerase chain reaction (Q-RT-PCR) assessing the amount of transcripts of the BCR/ABL gene, the molecular marker of chronic myeloid leukemia (CML), is the only method sensitive enough for monitoring of minimal residual disease (MRD) in CML patients after bone marrow transplantation (BMT). In this study we present a simple modification of competitive Q-RT-PCR using natural competitors from cell lines K562 and BV173. The competitors were used in the form of unpurified RNA in cell lysates which ensured their high stability. Mixing competitors and samples before RNA extraction eliminated problems with quantification of cDNA or RNA entering the competitive reaction and with checking for the RNA quality and reverse transcription (RT) efficiency. The bulk of the malignant clone was expressed as the number of leukemic cells in 10(6) leukocytes when the overproduction of the BCR/ABL mRNA in the cell lines we used as competitors was taken into account. It was found to be 82-fold and 14-fold in K562 and BV173, respectively, in comparison with 100% Ph-positive CML standard. The assay reliability was verified by comparison of results with the mathematical model of competitive PCR. The assay is highly reproducible and sensitive (10(-5)). Its accuracy was proved to be excellent in a wide range of malignant cell concentrations. The method is demonstrated on three CML patients suffering from MRD after BMT. In conclusion, this method fulfills all criteria of competitive Q-RT-PCR. Because of its simplicity it is suitable for clinical laboratories and due to the high stability of the lysates used it may serve in the standardization of results between different laboratories.

[Treatment of chronic myeloid leukemia with bone marrow transplantation at the Institute of Hematology and Blood Transfusion in Prague]

The outcomes of bone marrow transplantation (BMT) performed at the Institute of Haematology and Blood Transfusion from April 1988 to December 1994 in 31 patients with chronic myelogenous leukemia are presented. Age of the patients range from 18 to 49 years, median 34 years. Male:female ratio was 1.58:1. The conditioning regimen consisted of Cyclophosphamide and total body irradiation (TBI) or Busulfan and Cyclophosphamide. The results are evaluated as of January 1, 1995. Nineteen patients (61.3%) are alive, 12 patients (38.7%) died. The causes of death are discussed. The median time of follow up all patients is 10.4 months, range 0.3-81.5. The median time of follow up of surviving patients is 21.8 months, range 2.5-81.5. Probability of 2 years survival by Kaplan-Meier analysis is 58 +/- 10%. Of the 24 transplanted in the first chronic phase, 18 patients are alive. Of the 7 transplanted in advanced phase of the disease, 1 patient is alive. Of the 27 patients, who received bone marrow from an HLA identical sibling, 19 are alive. Of the 4 patients who received bone marrow from other donor than an HLA identical sibling, none is alive. Acute GvHD III.-IV. grade developed in 5 patients (16.1%), moderate and severe chronic GvHD developed in 11 patients (31.5%). Cytogenetic relapse was diagnosed in 1 patient, hematological relapse in 2 patients. Karnofsky scores of patients surviving after BMT range from 30% to 100%, median 90%.

[BCR and ABL gene rearrangement in chronic myeloid leukemia]

The fact of chromosome 9 and 22 translocation connected with the fusion of BCR and ABL genes occurring in 95% patients with chronic myeloid leukemia (CML) enables us to use molecular biology methods in CML diagnosis. By means of these methods we also can prove the rearrangement of BCR gene in some cytogenetically negative cases that are without so called Philadelphia (Ph) chromosome. 51 patients with myeloproliferative disease have been tested by Southern technique during the last year. The rearrangement of BCR gene was detected in 28 patients, in 13 of 14 patients where the Ph chromosome and also in 3 of 13 patients where the Ph chromosome was not detected. The detection of BCR gene rearrangement helped us to set the diagnosis of CML more precisely.

Molecular follow-up of patients after bone marrow transplantation

The follow-up of patients after bone marrow transplantation (BMT) revealed some discrepancies between red blood cell and white blood cell origin. In all six patients under study, the DNA analysis showed full engraftment, while red blood cells in some of them indicated persistence of recipient bone marrow activity. Abnormalities detected by the probe p362A (XY homologous region) in electrophoretic patterns observed during the period of graft versus host disease (GVHD) are discussed.

[Use of cytogenetic and molecular biology in the detection of chronic myeloid leukemia]

The examination of the presence of Ph chromosome and of the fused gene BCR-ABL in patients with chronic myeloid leukemia (CML) is significant for the precise diagnosis and in some cases for the prognosis of the disease. We examined peripheral blood for the presence of BCR-ABL fused gene by polymerase chain reaction (PCR) in eight patients with CML consecutively cytogenetically studied before and after the bone marrow transplantation and in two patients treated with interferon. Southern blot analysis was performed before BMT in two patients and the molecular rearrangement of Ph chromosome was found. In all cases our results have proved that cytogenetic and recombinant DNA evaluations confirm each other. Due to the high sensitivity of PCR technique the minimal residual leukemia can be detected.

Membrane potential in human myeloid leukemia cell line ML-1: responsiveness of granulocytic and monocytic differentiated cells

The membrane potential responsiveness of human myeloid leukemia cells (ML-1 line) was studied with the voltage sensitive fluorescent dye diS-C3-(5). The experimental procedure used in this study enabled us to assess the magnitude of the membrane potential change in cells treated with ouabain, 12-0-tetradecanoylphorbol-13-acetate (TPA) and N-formyl-L-methionyl-L-leucyl-L-phenylalanine (FMLP), relative to the membrane potential in the untreated control. Inhibition of the Na, K-ATPase by ouabain was followed by a (20 +/- 4) mV depolarization. In undifferentiated homogeneous cell population TPA caused a (19.4 +/- 4.4) mV depolarization while FMLP had virtually no effect. Cells in which granulocytic or monocytic differentiation was induced by retinoic acid or 1,25-dihydroxyvitamin D3 exhibited under the effect of TPA a (57.8 +/- 7.1) mV and (34.8 +/- 10.9) mV depolarization, respectively. A very small transient depolarization was also observed up on treating of the cells with FMLP. The changes in the membrane potential responsiveness in the induced cells are obviously connected with the cell differentiation.

Acrylonitrile depletes glutathione without changing calcium sequestration in hepatic microsomes and mitochondria

Acrylonitrile administered either in vivo or in vitro reduced the level of non-protein thiols, GSH and GSSG in rat liver (in vivo) and liver microsomes (in vitro). It neither influenced protein thiols nor calcium sequestration in the microsomes and mitochondria. The fact that the GSSG level was not increased indicates that a mere unoxidative depletion of GSH does not lead to impaired hepatocyte Ca homeostasis, which has been associated with decreased GSH:GSSG ratio. An opposite effect was caused by CCl4 which did not considerably change the protein and non-protein SH, but strongly decreased microsomal calcium sequestration.

Rubidium transport in X-irradiated human erythrocytes

Outflow of 86Rb, a radioactive analogue of potassium, from human erythrocytes X-irradiated in vitro was studied with the following results. (1) The 86Rb level in the supernatants of irradiated and control cell suspensions reflected mainly 86Rb outflow and much less its active re-uptake. (2) The effect of irradiation on 86Rb outflow was more pronounced at a low temperature (4 degrees C) than at 37 degrees C; the lowest dose of X-radiation exhibiting a significant effect on 86Rb outflow at 4 degrees C was 2.5 Gy. (3) K/Rb exchange did not seem to play an appreciable role in radiation-induced 86Rb outflow. (4) Calcium and its accumulation in irradiated cells was not found to be the cause of the effect of radiation on 86Rb outflow. (5) The effect of radiation on 86Rb outflow was higher in low Na medium but it was not inhibited by bumetanide. Rb/Na counter- or co-transport do not therefore seem to be involved in radiation-induced Rb+ outflow.

Isolation and chemical characterization of a highly purified phytomitogen from Phaseolus coccineus seeds

An effective lymphocyte mitogen with a low erythroagglutinating ability was isolated from the seeds of Phaseolus coccineus L. by ammonium sulphate precipitation and repeated ion-exchange chromatography on modified Sephadex. The mitogen stimulated lymphocytes at concentrations as low as 0.25 microgram/ml, the optimum concentration being in the range of 2.5-5.0 microgram/ml. This stimulating effect was completely inhibited by 5 mg/ml methyl alpha-D-mannopyranoside. Column gel filtration, disc electrophoresis on polyaceylamide gel in an alkaline medium and in the presence of sodium dodecylsulphate and the finding of a single N-terminal amino acid (alanine) showed the phytomitogen to be homogenous. Disc electrophoresis in an acid medium revealed the presence of two or three bands which are assumed to be due to aggregates of the mitogen. The minimum molecular weight, as derived from sodium dodecylsulphate electrophoresis on polyacrylamide, was 35000. The mitogen is a glycoprotein containing 10% neutral sugars and 1.3% amino sugars (glucosamine). The amino acid composition of the isolated phytomitogen is presented.

Studies on lectins. XXXVIII. Isolation and characterization of the lectin from black locust bark (Robinia pseudacacia L.)

The lectin of black locust (Robinia pseudacacia) bark was isolated by specific adsorption on formaldehyde-fixed human erythrocytes and elution with a borate solution. The lectin is homogeneous on disc electrophoresis and ultracentrifugation (s20,w = 5.8 S) but yields three bands on isoelectric focusing. It has a molecular weight of approximately 110,000 and consists of two types of subunit (mol. wt 29,000 and 31,500). Its pI is approximately 5.9; it contains high amounts of aspartic acid, threonine and serine, no cysteine and very little methionine. Also 7.2% of covalently bound neutral sugar and 0.47% of glucosamine are present. The lectin is nonspecific in agglutination of human erythrocytes, it is inhibited by high concentrations of N-acetyl-D-galactosamine and is mitogenic in rabbit lymph node lymphocytes.