[Septicemia due to methicillin-resistant Staphylococcus aureus from chronic prurigo in an elderly woman]

An 80-year-old woman being treated with anti-hypertensive drugs developed eruption and itching of the skin. High fever and lymph node enlargement subsequently developed in spite of discontinuing all antihypertensive drugs, and she was admitted to our hospital. At the initial examination, multiple papules were noted over the entire body, and the skin showed thickening and lichenification with scratch marks. There was also generalized enlargement of the superficial lymph nodes. From these findings, her condition was diagnosed as chronic prurigo due to drug allergy. Laboratory tests showed inflammatory findings, anemia and a high serum level of IgE. Analysis of the surface marker of peripheral lymphocytes revealed no abnormalities. Bacteriologic cultures of blood revealed methicillin-resistant Staphylococcus aureus (MRSA). Histologic examination of the lymph nodes revealed chronic reactive lymphadenitis with a follicular pattern. She was strongly suspected of having MRSA septicemia, and so combination chemotherapy with vancomycin, minocycline and cefoperazone/sulbactam was started. However, 1 month after initiation of chemotherapy, the low-grade fever, eruption and moderate inflammatory findings persisted, and culture of the eruptions revealed MRSA. The prurigo was therefore considered to be the source of the septicemia, and daily application of diflucortolone ointment containing 3% acetic acid was started. Thereafter, the clinical and laboratory findings showed a rapid improvement. MRSA infections usually occur in compromised patients who are receiving antibiotics during prolonged hospitalization. The present case, who did not have any underlying disease, indicates that old-age is also an important factor for the development of MRSA septicemia.

Long-term survey on intestinal nematode and cestode infections in stray puppies Ibaraki Prefecture

We conducted the survey on intestinal nematode, mainly Toxocara canis, and cestode infections in stray puppies aged less than 5 months in Ibaraki Prefecture for 8 years from 1988 to 1995. The rate of T. canis infection stayed almost unchanged for the 8 years and ranged from 72.2 to 85.4%. Of the total 916 dogs, 732 (79.9%) harboured with T. canis. The average rates of other helminthic infections showed 24.6 (Diphylidium caninum), 2.5 (Trichuris vulpis), 1.2 (Ancylostoma caninum) and 0.7% (Spirometra erinaceieuropaei) respectively.

Correlation between expression of platelet-derived endothelial cell growth factor (thymidine phosphorylase) and microvessel density in early-stage human colon carcinomas

Platelet-derived endothelial cell growth factor may play a role in tumor development through its angiogenic action. To clarify the relationship between expression of platelet-derived endothelial cell growth factor and microvessel density in the development of human colon carcinoma, we examined 80 early-stage colon carcinomas using microscopy and immunohistochemistry. Localization of platelet-derived endothelial cell growth factor was assessed by immunocytochemistry, while microvessel count was evaluated by either HE staining or Factor VIII immunostaining. Among the examined carcinomas, 35 were classified as m carcinomas including carcinoma in situ, whereas 45 were sm carcinomas. Fifteen (42.9%) of the 35 m and 30 (66.7%) of the 45 sm carcinomas demonstrated high vascular density, whereas 20 (57.1%) m and 15 (33.3%) sm carcinomas showed moderate or low vascular density. Vascular density was higher in sm carcinomas than in m carcinomas and there was a significant correlation between depth of invasion and vascular density. Of the 45 highly vascularized carcinomas, 44 expressed platelet-derived endothelial cell growth factor. There was a statistically significant correlation between the frequency of platelet-derived endothelial cell growth factor expression and microvessel density (P = 0.012). These data demonstrate that microvessel density may be associated with the depth of cancer invasion and that platelet-derived endothelial cell growth factor may play an important role in the early stage of colon cancer development through angiogenesis.

Serum carcinoembryonic antigen concentration doubling time correlates with tumor biology and life expectancy in patients with recurrent gastrointestinal carcinoma

OBJECTIVE

To determine if carcinoembryonic antigen (CEA) concentration doubling time (DT) can predict the course of disease and characterize tumor biology.

DESIGN

Retrospective case series of patients who exhibited a distinct increase in circulating CEA during disease recurrence in the routine postoperative follow-up.

SETTING

A tertiary general hospital.

PATIENTS

Twenty patients with recurrent gastric carcinoma and 17 patients with recurrent colorectal carcinoma.

INTERVENTION

The CEA DT was determined from semilogarithmic plots of CEA concentration time courses.

MAIN OUTCOME MEASUREMENTS

The quantitative analyses of the CEA DT as related to various host and tumor characteristics, modes of recurrence, and life expectancy.

RESULTS

The mean CEA DTs for gastric and colorectal carcinomas were 229 days and 86 days, respectively. Although there were no significant differences with regard to patient age, tumor size, gross appearance, and histological differentiation, women had shorter CEA DT than did men. Flow cytometric analysis showed that tumors with a higher proportion of cells in S phase (> or = 15%) had significantly shorter CEA DT than those with a lower S-phase fraction (< 15%). There was a significant correlation between the CEA DT and the length of survival after the initial CEA concentration increase in patients with recurrent gastric and colorectal carcinomas. In the multiple regression analysis of patients who had been treated with curative surgery and chemotherapy, CEA DT proved to be a major independent prognostic factor.

CONCLUSIONS

Carcinoembryonic antigen DT predicts life expectancy in patients with adenocarcinoma of the gastrointestinal tract. Differences in survival time are closely associated with variations in the biological aggressiveness of individual tumors.

Efficacy of doramectin against intestinal nematodes and sarcoptic manage mites in naturally infected swine

Endectocidal efficacy of doramectin administered intramuscularly at a dosage of 300 micrograms/kg was evaluated in 464 pigs naturally infected with intestinal nematodes or mange mites on 14 commercial farms in Japan. By doramectin treatment, fecal egg counts were reduced > 99% for Ascaris suum, Strongyloides ransomi, Oesophagostomum dentatum, and Trichuris suis; worm counts of T. suis and mite counts of Sarcoptes scabiei reduced 90.1% on Day 21 and 99.5% on Day 28 following treatment, respectively.

[Granisetron versus granisetron plus methylprednisolone in the prevention of chemotherapy induced nausea and vomiting--in adjuvant chemotherapy, including CDDP against gastric cancer]

CDDP is one of the most effective drugs in chemotherapy for gastric cancer. We compared the antiemetic effect of a combination of granisetron and methylprednisolone with that of granisetron administered alone. Twenty postgastrectomy-patients who were to receive moderately emetogenic chemotherapy, including CDDP, were enrolled in randomized fashion to evaluate the efficacy and toxicity of two antiemetic regimens. The following antiemetic regimens were used: 3 mg of granisetron given intravenously before chemotherapy (11 patients) or a combination of granisetron and 250 mg of methylprednisolone in the same manner (9 patients). Granisetron combined with methylprednisolone tender to be more effective than granisetron alone. The adverse effects were very mild. Their efficacy against delayed emesis is still not entirely satisfactory.

A comparison of open and laparoscopic cholecystectomy for patients with cirrhosis

To evaluate the benefits of performing laparoscopic cholecystectomy (LC) in patients with cirrhosis, data on 13 patients with liver cirrhosis who underwent cholecystectomy for gallstones between 1989 and 1995 were retrospectively collected from charts filed at Fukuoka City Hospital. These 13 patients were classified into two groups; one, comprised of 7 who underwent LC, and another, comprised of 6 who underwent open cholecystectomy (OC). No statistical differences were observed in the duration of surgery or the intraoperative blood loss between the two groups; however, the C-reactive protein (CRP) level in the serum was significantly higher in the OC group than in the LC group. LC was followed by a significantly earlier resumption of a normal diet (P < 0.05) and a shorter hospital stay (P < 0.05) in comparison to OC. All of the patients who underwent OC had an uneventful clinical course; however, one of the patients who underwent LC suffered from intractable ascites postoperatively. The difference in the cost of hospitalization between the two groups was not statistically significant. These findings suggest that the therapeutic significance of performing LC in patients with cirrhosis should be assessed after carefully evaluating all factors including mortality, morbidity, and cost-effectiveness. Thus, further controlled trials are necessary.

[Chemotherapy for peritoneal dissemination in gastric cancer under ureteral catheterization]

The treatment of peritoneal dissemination of gastric cancer is mainly chemotherapy, but it use is often limited by ileus, hydronephrosis and jaundice. We employed a ureteral catheter for 6 patients with hydronephrosis due to peritoneal dissemination. Chemotherapy (CDDP + ADM + 5-FU or MTX + 5-FU) was administered in 5 patients. After ureteral catheterization, renal function was kept within normal ranges, so chemotherapy was performed safely. One of five patients became CR and the effect of the treatment was satisfactory (PR: 1, NC: 2). Thus, chemotherapy after ureteral catheterization may be effective for patients with peritoneal dissemination and hydronephrosis.

HLA-DM gene polymorphisms in atopic dermatitis

HLA-DM molecules are involved in the antigen-processing pathway of HLA class II-restricted antigen presentation. We investigated polymorphisms of HLA-DM genes in atopic dermatitis by using the polymerase chain reaction-restriction-fragment length polymorphism method to examine a possible contribution of these genes to the pathogenesis of atopic dermatitis. Genomic DNA was extracted from 37 Japanese patients with atopic dermatitis and 52 control subjects. After polymerase chain reaction amplification of the polymorphic third exon of DMA and DMB genes, amplified products were digested with restriction endonucleases to determine HLA-DM alleles. FokI, HinfI, AciI and SfaNI were used for DMA; HhaI, BsrI, ApaLI, and Bsp1286I for the DMB gene. We identified three DMA alleles and also three DMB alleles. One of 37 patients possessed the DMA*0103 allele, which has been reported as a rare allele in Caucasian populations. Any DMA and DMB alleles were not increased in the patients. The DMA*0102 allele was estimated to constitute a haplotype with DRB1*1201/DQB1*0301 and DRB1*0901/DQB1*0301 in a Japanese population. HLA-DM genes are not considered to contribute primarily to the susceptibility of atopic dermatitis. Further investigation of the functional roles of HLA-DM gene polymorphisms will be useful for a better understanding of susceptibility loci in HLA class II-associated disease.

MUC1-specific targeting immunotherapy with bispecific antibodies: inhibition of xenografted human bile duct carcinoma growth

For the purpose of establishing a new adoptive immunotherapy for bile duct carcinoma (BDC), we synthesized two bispecific antibodies (BsAbs), MUC1 x CD3 BsAb constructed with MUSE11 (anti-MUC1 tumor antigen) and OKT-3 (anti-CD3), and MUC1 x CD28 BsAb constructed with MUSE11 and 15E8 (anti-CD28) antibodies. These two BsAbs reacted well with both MUC1-positive target tumor cells and effector lymphokine-activated killer (LAK) cells. Investigation of in vitro cytotoxicity [3-(4,5-dimethylthiazo-2-yl)-2,5-diphenyltetrazolium bromide assay] revealed that the MUC1 x CD3 BsAb could antigen-specifically enhance the cytotoxicity of LAK cells. Addition of the two BsAbs (MUC1 x CD3 BsAb plus MUC1 x CD28 BsAb) in vitro resulted in a 60% cytotoxicity, similar to that obtained with BsAb (MUC1 x CD3) alone. Interleukin 12-induced LAK cells demonstrated far greater cytotoxicity (50%) than their interleukin 2-induced counterparts (LAK cells), and this was also enhanced by the BsAbs. When 2 x 10(7) LAK cells sensitized with both kinds of BsAbs were administered four times i.v. to BDC-grafted severe combined immunodeficient mice (tumor size 5 mm in diameter), inhibition of tumor growth was observed. Thus, BsAb-LAK therapy for control of BDC warrants clinical trials.

A fibrous histiocytoma with a polypoid pattern of growth in a major bronchus

A 47-year-old man was admitted to our hospital for abrupt onset of hemoptysis and dyspnea. Chest roentgenography revealed a left lower mass shadow with obstruction of the left main bronchus. However, on the third hospital day, he expectorated a coagulum-like substance which resembled bronchial tree, and his symptoms then dramatically subsided. Except for small amounts of bleeding from left B10a, the endobronchus was intact on bronchoscopic examination, and the pathologic diagnosis of the tumor using resected material was fibrous histiocytoma of low-grade malignancy. In addition, given the similarity in histologic findings between the expectorated substance and resected tumor, the expectorated substance was considered to be a part of the tumor which had grown along the endobronchial tree.

Thrombotic occlusion of the coronary artery associated with accidental detachment of undeployed Palmaz-Schatz stent

We describe a case of coronary stenting in which accidental detachment of the Palmaz-Schatz stent induced thrombotic occlusion of the coronary artery. This case suggests that careful consideration of the risk involving coronary occlusion is mandatory on deciding the therapeutic strategy of the cases in which the unexpanded coronary stent cannot be retrieved following successful deployment.

Erythrocyte oxidation in artificial Babesia gibsoni infection

We have already reported that anti-erythrocyte antibody induced by Babesia gibsoni infection (aEAb) showed higher reactivity against aged and/or oxidized erythrocytes than intact one in vitro (Morita et al., 1995). To clarify the meaning of such a binding character of aEAb in vivo, changes in erythrocyte oxidation were observed in artificially infected dogs. The ratio of methemoglobin concentration against total hemoglobin concentration (metHb%) as the indicator of erythrocyte oxidation was increased by the artificial infection in the intact dogs, suggesting that aEAb played a more important role in erythrocyte destruction in infected dogs. Though parasitemia approximately three times higher was observed in splenectomized dogs than that in intact dogs, metHb% did not increase in the splenectomized dogs. This suggests that the spleen plays a very important role in erythrocyte oxidation in dogs infected with B. gibsoni.

The treatment of gastric varices by a balloon-occluded retrograde transvenous obliteration; a transjugular venous approach

Two Japanese women with a solitary gastric varix were successfully and easily treated by obliterating the gastro-renal shunt with a balloon catheter in a transjugular venous approach without any major complications. The transjugular obliteration was thus found to be a bloodless and useful method for the treatment of a solitary gastric varix with a gastro-renal shunt.

[Changes in serum lipoprotein (a) levels related to hyperlipidemia during pregnancy--comparing normal pregnancy and toxemia of pregnancy]

In this study, we investigated fluctuations in serum lipoprotein (a) (Lp(a)) levels in normal and toxemic pregnancy. We measured serum total cholesterol (TC), triglyceride (TG), phospholipid (PL), high-density lipoprotein (HDL), apolipoprotein and Lp(a) levels in 33 normal pregnant and 11 toxemic pregnant women at delivery and in 47 normal pregnant women throughout gestation. Lp(a) and apolipoproteins were detected by turbidimetric immunoassay. The levels of serum lipids, HDL and apolipoproteins were all increased in pregnancy. In toxemia of pregnancy, serum TC and PL levels were lower (p < 0.05) and the apolipoprotein C-III level was higher (p < 0.005) than in normal pregnancy. Serum Lp(a) levels increased until the 20th week and reached a value which was 1.5 times higher than at the 10th week. Thereafter Lp(a) levels were constant until the late stage of pregnancy. In contrast, serum TC and TG levels increased steadily throughout gestation. The serum Lp(a) level was 18.1 +/- 27.5mg/dl in normal pregnancy and 17.8 +/- 17.9mg/dl in toxemia of pregnancy. These results revealed changes in serum Lp(a) levels during pregnancy. Further studies will be required to clarify the metabolic control of Lp(a) in pregnancy and the matabolic disorders of lipids and lipoproteins in toxemia of pregnancy.

A new in vitro model of specific targeting therapy of cancer: retargeting of PWM-LAK cells with bispecific antibodies greatly enhances cytotoxicity to hepatocellular carcinoma

For the purpose of establishing a new in vitro model of adoptive immunotherapy, we synthesized two kinds of bispecific antibodies (BsAbs), i.e., (OK x L) BsAbs constructed with both OKT-3 (anti-CD3) and L-7-6 (anti-HCC), and (3G x L) BsAbs constructed with 3-G-8 (anti-CD16) and L-7-6 antibodies. These two BsAbs, having pairs of binding arms on their single molecule, showed similar binding to target cells as the parental monoclonal antibodies (OKT-3, 3-G-8 and L-7-6), when examined with FACS. Newly devised in vitro cytotoxicity tests revealed that LAK or PWM-stimulated LAK (PWM-LAK) cells did not show any significant cytotoxic activity to HCC cells, while both effector cells equally showed greatly enhanced cytotoxicity to HCC even at a low effector/target (0.3) in the presence of BsAbs (OK x L) for the efficient retargeting of the effector cells. Inasmuch as PWM-LAK cells proliferate in vitro 3-5 times faster than LAK cells, adoptive immunotherapy using PWM-LAK cells in combination with (OK x L) BsAbs should be very promising.

Effect of silica treatment on resistance to Babesia rodhaini infection in immunized mice

The effect of silica treatment on the course of Babesia rodhaini infection was investigated in ICR mice pretreated with either a mixture of B. rodhaini parasitized red blood cell hemolysation-sonication (S) antigen and Propionibacterium acnes bacterin or P. acnes bacterin alone and not subjected to immunization. In the normal mice (non-immunized), the mean survival time was decreased by approximately 1 day when 5 mg per mouse of silica were intraperitoneally inoculated at 5 h before infection. In immunization with S antigen and P. acnes bacterin, all mice survived regardless of the dose of silica (15-25 mg per mouse) treatment. In contrast, in immunization with P. acnes bacterin alone, 3/10, 4/10 and 1/10 mice died of B. rodhaini, when inoculated with 15 mg per mouse, 20 mg per mouse and 25 mg per mouse of silica treatment 5 h before infection, respectively. These results suggest that peritoneal macrophages (M luminal diameter of), especially when activated non-specifically by P. acnes bacterin, play an important role in inhibiting multiplication of organisms at the early stage of infection and the mice immunized with S antigen were ready to quickly acquire an enhanced solid specific protection even if the function of M luminal diameter of was damaged by a high dose of silica treatment.

A case of generalized pustular psoriasis followed by bullous disease: an atypical case of bullous pemphigoid or a novel bullous disease?

We describe a 31-year-old Japanese woman with generalized pustular psoriasis treated with PUVA who subsequently developed a bullous disease. Throughout the disease course, there was no phase of psoriasis vulgaris. Although several reports describe coexistence of psoriasis vulgaris and bullous disease such as bullous periphigoid, coexistence of generalized pustular psoriasis without any phase of psoriasis vulgaris and bullous disease is rare. As for the bullous disease, direct immunofluorescence study showed IgG and C3 deposition along the basement membrane zone. Indirect immunofluorescence disclosed IgG antibasement membrane zone antibodies. Indirect immunofluorescence on 1 mol/l sodium chloride-split skin demonstrated linear IgG staining almost exclusively on the dermal side of the split. Western immunoblot analysis revealed that the antibody was directed to neither epidermolysis bullosa acquisita antigen nor bullous pemphigoid antigens. Considering the unusual clinical course, we suspect the possibility of a novel autoimmune blistering disease.

Analysis of disease-associated amino acid epitopes on HLA class II molecules in atopic dermatitis

We investigated the association between HLA class II alleles and severe atopic dermatitis with high serum IgE levels (greater than 8000 U/ml). The frequencies of HLA-DRB1*1302 and DQB1*0604 were increased, whereas the frequency of HLA-DQB1*0302 was decreased. A strong haplotype, HLA-DRB1*1302-DQB1*0604, has been reported in the Japanese population, and this haplotype is conserved in patients with AD. Further analysis of the amino acid epitopes on the HLA-DR beta 1 and DQ beta 1 domains revealed that DR beta 1 71Glu (RR = 5.71, p < 0.05) and DQ beta 1 30His (RR = 3.25 p < 0.01), and 57Val (RR = 3.13, p < 0.05) were increased in frequency. DR beta 1 71Glu was exclusively unique to DRB1*1302. DQ beta 1 30His was shared by the following alleles: DQ beta 1*0501, *0502, *0503, and *0604, which were all increased in patients with AD. DQ beta 1 57Val was shared by DQB1*0501 and *0604. A well-known haplotype, HLA-DRB1*1302-DQB1*0604, contains DR beta 1 71Glu and DQ beta 1 30His and 57Val. Therefore HLA-DR beta 1 71Glu and/or DQ beta 1 30His/57Val are considered to play the most important role in the development of atopic dermatitis.

Lack of primary association between transporter associated with antigen processing genes and atopic dermatitis

We examined polymorphisms of transporter associated with antigen processing (TAP) genes in 37 Japanese patients with atopic dermatitis and 52 control subjects. We have evaluated, again, the specificity polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method since our previous report and have also developed a mismatch PCR-RFLP method for discriminating two dimorphic sites of TAP1 gene and four dimorphic sites of TAP2 gene. Amplified products from genomic DNA were digested with restriction endonucleases: Sau3A1 for TAP1 codon 333 (Ile-Val), AccI for TAP1 codon 637 (Asp-Gly), and BfaI for TAP2 codon 687 (Stop-Gln). The other sites of TAP2 gene were analyzed by mismatch PCR-RFLP: AccII for TAP2 codon 379 (Val-Ile), RsaI for codon 565 (Ala-Thr), and MspI for codon 665 (Thr-Ala). We observed three TAP1 alleles and six TAP2 alleles. Infrequent allele TAP1 C was observed in one patient and one control subject. We did not identify any differences in TAP allele frequencies between those patients with atopic dermatitis and Japanese control subjects. Analysis of TAP gene polymorphisms will provide better understanding of susceptibility loci in HLA class II-associated disease because TAP genes are located between HLA-DQB1 and HLA-DPB1 loci.

Evaluation of anthelmintic efficacy of doramectin against gastrointestinal nematodes by fecal examination in cattle in Japan

The nematocidal effect of doramectin was assessed by subcutaneous injection of 200 micrograms/kg (single dosage) in cattle with naturally acquired gastrointestinal nematode infection in Japan. This study consisted of two experiments. In experiment 1, animals were randomly divided into a doramectin group (n = 21) and a non-treated control group (n = 21) by fecal egg count. In experiment 2, another group of ivermectin treatment (n = 12) was prepared in addition to doramectin (n = 23) and control (n = 10) groups, by random assignment as in study 1. After doramectin or ivermectin treatment, the egg count/5 g of feces was measured by the sucrose centrifugal flotation method at intervals of 7 days until Day 21 in experiment 1 and at Days 7, 14, 21, 35, 42, 49 and 63 in experiment 2. Coproculture was also carried out using some of the fecal samples. In the 2 doramectin-treated groups, 96.1%-100% egg reduction rates were obtained for Haemonchus, Cooperia, Mecistocirrus, Trichostrongylus, Ostertagia, Bunostomum, Strongyloides and Trichuris from the 7th day until the 49th day after treatment. Thus doramectin was confirmed to be highly effective against those species of adult nematoda. The effect against Mecistocirrus has not been previously determined. The nematocidal effect against Nematodirus was lower (egg reduction rate approximately 50%) than other species. No adverse reactions to treatment were seen in any animal during either study.

Massive experimental infection with Strongyloides venezuelensis in rats and absence of sudden death

Ten rats were divided into five groups, A - E, to determine the larval dose-effect of infection with Strongyloides venezuelensis (SVZ). The rat groups were exposed to SVZ infective larvae as follow: (A) 100, (B) 1,000, (C) 10,000, (D) 100,000 and (E) 1,000,000. The eight rats in Groups A - D survived the infection. Rats exposed to the higher doses of larvae had the higher egg per gram counts (EPG), but more rapid reduction in EPG counts. The four rats in Groups C and D had EPG counts greater than 10,000 EPG during days 7 - 21 after infection. Maximum EPG values in Group C were 85,400 and 106,600; those in Group D were 134,000 and 346,000. The two rats in Group E showed severe itching and bleeding on their digital pads at the time of infection. They became listless thereafter and died with hemorrhagic pneumonia at 4 days after infection. The sudden death that has been demonstrated in calves infected with massive doses of S. papillosus was not observed in SVZ-infected rats.

A novel human monoclonal antibody, TONO-1, reactive with T-lymphocytic leukemia cells

Mononuclear cells from the peripheral blood of patients with systemic lupus erythematosus (SLE) were transformed with the Epstein-Barr virus (EBV) and the resultant polyclonal B-lymphoblastoid cell lines were tested for antibody activity to membrane antigens of certain T-cell lines. B lymphoblastoid cell lines secreting specific antibodies were fused with (mouse x human) heteromyeloma SHM-D33 cells. Among the large number of hybridomas generated, one which produced a human monoclonal antibody (MAb) TONO-1 (IgM, lambda) was selected. MAb TONO-1 proved to be reactive with 4 human T-cell lines, HPB-MLT, L-MAT, MOLT-3 and MOLT-4F, but not with B-leukemia, Burkitt's lymphoma, myelomonocytic leukemia, erythroleukemia or non-hematopoietic malignant cell lines. MAb TONO-1 reacted positively with fresh leukemia cells from 2 of 7 patients with acute T-lymphocytic leukemia, but no reaction was observed in non-T-cell leukemia cases. Normal lymphocytes, monocytes, granulocytes, red blood cells and platelets in the peripheral blood did not demonstrate remarkable binding. Neither thymocytes nor bone-marrow cells from healthy volunteers were reactive. The antigens defined by MAb TONO-1 were polypeptides of 57 kDa and 68 kDa. Immunohistological studies revealed no staining of thymocytes in the thymus of a 6-month-old child, but showed epithelial reticular cells and Hassall's corpuscles to stain positively. These results suggest that MAb TONO-1 is directed to T-leukemic cells and some components of thymus tissue.