Mutations of connexin32 in Charcot-Marie-Tooth disease type X interfere with cell-to-cell communication but not cell proliferation and myelin-specific gene expression

Connexin32 (Cx32) is a gap junction protein and its mutations are responsible for X-linked Charcot-Marie-Tooth disease. We examined the functional abnormality of C6 glioma cells transfected with mutant (C53S and P172R) Cx32 genes. Nontransfected C6 did not express Cx32. Northern and Western blot analyses showed Cx32 mRNA and protein in cells with the wild-type gene as well as with the mutant Cx32 genes. An immunocytochemical study of cells with the wild-type gene showed the immunoreactive spots in the cell membrane. In cells with C53S or P172R mutant gene, however, the immunoreactivity was found in the cytoplasm. The scrape-loading method produced effective dye transfer in cells with the wild-type gene but not in those with mutant genes. A cell proliferation assay showed no differences in nontransfected cells, cells with the wild-type gene and those with the mutant genes. Messenger RNA expression for proteolipid protein did not change. These findings suggest that Cx32 gene mutation results in loss of cell-to-cell communication because of failure to incorporate Cx32 protein in the cell membrane. The mutations do not, however, interfere with cell proliferation or myelin-specific gene expression, at least myelin proteolipid protein expression in C6 glioma cells.

[Granulomatous slack skin]

A 48-year-old woman developed granulomatous slack skin (GSS), one of the special forms of cutaneous T-cell lymphoma. The lesional skin slack with an atrophic, poikilodermic surface and granulomatous induration. Histopathological findings included epidermotropism, diffuse lymphoid cell infiltration and foreign body giant cells as well as granulomatous reactions from superficial to deep dermis, including part the subcutis. The diagnosis was established by positive results for rearrangement of the T-cell receptor gene. The therapeutic possibilities, especially with corticosteroids and monitoring the disease course by following serum angiotensin converting enzyme activity are discussed.

Pericellular deposition of basement membrane material in myxoid meningioma: immunohistochemical evidence for unbalanced production of type IV collagen and laminin

Myxoid meningioma seen in a 25-year-old man is presented. Histologically, Leu 7-positive meningotheliomatous tumor cells were embedded in the alcianophilic myxoid matrix. Characteristically, eosinophilic granular deposition was detected around the tumor cells and the boundary of tumor cells was not clearly defined. The pericellular deposits revealed the nature of the basement membrane with positive reactions by periodic acid-Schiff (PAS) sequence and immunostaining for type IV collagen, which is the major structural component of basement membrane. However, laminin, which is a non-collagenous glycoprotein of the basement membrane, was undetectable, and silver was not impregnated. Similar abnormal deposition of PAS-positive basement membrane-like material was observed in the myxoid stroma of a microcystic meningioma among 72 meningiomas additionally examined. The significance of the discrepant localization of immunoreactive type IV collagen and laminin is discussed.

Amino acids and peptides. XXXII: A bifunctional poly(ethylene glycol) hybrid of fibronectin-related peptides

An amino acid type poly(ethylene glycol) (aaPPEG) was prepared and its application to a drug carrier was examined. The peptides, Arg-Gly-Asp (RGD) and Glu-Ile-Leu-Asp-Val (EILDV) which were reported as active fragments of Fibronectin (a cell adhesion protein), were conjugated with aaPEG (molecular weight, 10,000). The hybrid, RGD-aaPEG-EILDV, was prepared by a combination of the solid-phase method and the solution method. Antiadhesive activity of the peptides was not lost by its hybrid formation with the large aaPEG molecule. A mixture of RGD (0.43 mmol) and EILDV (0.43 mmol) did not demonstrate an antiadhesive effect, but the hybrid containing 0.43 mmol of each peptide did exhibit this effect.

Ovarian endometrioid adenocarcinoma associated with steroidogenic foamy stromal cells

A case of 69-year-old woman with endometrioid adenocarcinoma of the ovary with functioning stromal cells is presented. The patient complained of genital bleeding. Endometrial curettage revealed endometrial hyperplasia. Pre-operative levels of serum estradiol and progesterone were elevated, and serum gonadotropin levels were suppressed. The surgical specimen contained fist-sized, bilateral, solid, ovarian tumors and a mildly enlarged uterus. Histologically, the proliferating, atypical, columnar cancer cells resembled early secretory, endometrial epithelial cells with subnuclear vacuolation, and there were clusters of fat-laden foamy cells in the stroma. Immunohistochemically, the cancer cells were positive for cytokeratin and progesterone receptor but negative for estrogen receptor. The stromal foamy cells were immunoreactive for vimentin, progesterone receptor, P450 side chain-cleavage, 3 beta-hydroxysteroid dehydrogenase, and adrenal 4-binding protein. Immunoreactivities of P450c-17 alpha hydroxylase and aromatase were only focally observed. These findings indicated that the stromal cells were steroidogenic and mainly produced progesterone. The cancer cells that expressed progesterone receptors showed morphologic changes in response to hormonal stimulation.

Effect of additives on dissolution and swelling of soybean lecithin microcapsules prepared using the Wurster process

Microcapsules whose membranes contained soybean lecithin (SL), cholesterol (CH), stearic acid (SA) and polyvinylpyrrolidone (PVP) at various compositions were prepared. Then, dissolution and swelling behaviors of the microcapsules in a 0.9% saline solution were studied to be related to the phase diagram of three components containing 42% of PVP in anhydrous state. In the aqueous solution, when an anhydrous microcapsule membrane was composed of SL not saturated with both CH and SA, the microcapsules showed rapid release of carbazochrome sodium sulfonate (CCSS, a model drug), poor particle-swelling and spouting of droplets containing CCSS. Long-delayed release of CCSS and drastic particle-swelling with no spouting of droplets were observed when the anhydrous membrane was composed of SL saturated with both CH and SA and the composition was not close to the two-component line, CH-SA, or to the saturation line. The spouting of droplets would be attributable to the CH and/or SA-poor SL phase and to the SL phase which dissolved CH and SA, but contained either CH or SA only in a small amount, and the delayed release would be due to the CH and SA-rich SL phase dissolving a great amount of CH and SA formed by hydration. The degree of release suppression and particle-swelling depended on the SL content. At 20-45% of SL content, the prolonged-release, great particle-swelling and no spouting of droplets at the early stage were observed only when the CH and SA-rich SL phase formed by hydration contained a high content of CH and SA.

Positively charged liposome functions as an efficient immunoadjuvant in inducing immune responses to soluble proteins

To design an optimum liposome immunoadjuvant for soluble protein antigens, we investigated the relationship between liposomal surface charge and adjuvant action. Positively charged multilamellar vesicles (MLV) were taken up efficiently by macrophages, while negatively charged and neutral MLVs were hardly picked up. Consistent with this, positively charged MLVs containing soluble chicken egg albumin (OVA) functioned as a more potent inducer of antigen-specific cytotoxic T lymphocyte (CTL) responses and antibody production than negatively charged and neutral MLVs containing the same concentrations of antigens. These results indicate that the positive charge on the surface of liposomes represents an important factor for enhancing their immunoadjuvancy in the induction of antigen-specific immune responses.

Amino acids and peptides. XXX. Preparation of Arg-Gly-Asp (RGD) hybrids with poly(ethylene glycol) analogs and their antimetastatic effect

Hybrids of a fibronectin-related peptide[Arg-Gly-Asp (RGD)] with poly(ethylene glycol) (PEG) analogs were prepared by a simple and easy procedure. Two amino-PEG analogs were used as carriers for hybrid formation of the RGD. One was poly(oxyethylene)dipropylamine and the other was Jeffamine ED type, which has branched chains. RGD peptides were formed stepwise on PEG analogs by the diisopropylcarbodiimide method. The synthetic intermediates were easily purified by molecular-sieve gel chromatography and the final products were purified by molecular-sieve gel chromatography, followed by HPLC. This simple and easy preparation procedure using molecular-sieve gel chromatography for purification of synthetic intermediates is advantageous for the preparation of peptide-polymer hybrids. We found that PEG is stable to HF treatment at 0 degree C for 1 h. The inhibitory effect of the RGD hybrids on experimental metastasis of B16-BL6 was examined in mice. The Jeffamine type hybrid showed no inhibitory effect at the dose of 1 mg/mouse, but poly(oxyethylene)dipropylamine type hybrid was inhibitory at the same dose. The effect of the latter hybrid was about the same as that of 1 mg of RGD. One mg of the hybrid contains 0.18 mumol of RGD and 1 mg of RGD is 2.38 mumol. Thus it can be said that the inhibitory effect of RGD was potentiated by hybrid formation with poly(oxyethylene)diisopropylamine.

Ciliate protozoa in the rumen of sassaby antelope, Damaliscus lunatus lunatus, including the description of a new species and form

Composition of rumen ciliate fauna in five Zambian, sassaby antelopes was determined. Six genera, 18 species, and four forms were identified. One new species and form, belonging to the subfamily Diplodiniinae, were found, then labeled Ostracodinium damaliscus n. sp. and Diplodinium bubalidis f. aspinosum n. f., respectively. Only ophryoscolecid species were present while isotrichids were absent. Twelve of 18 total species are commonly found in African antelopes. Three of those 12 species, Entodinium fyferi, Enoploplastron garstangi and Opisthotrichum janus, are only found in African antelopes. Percentage composition was low in the genera Enoploplastron, Eudiplodinium and Entodinium, and high in the genus Opisthotrichum. The average density of ciliates was 3.1 x 10(5)/ml of rumen fluid, and the average number of ciliate species per host was 17.2.

Bioconjugation of tumor necrosis factor-alpha with the copolymer of divinyl ether and maleic anhydride increasing its antitumor potency

To enhance the therapeutic usefulness of antitumor cytokines in vivo, we synthesized bioconjugated tumor necrosis factor-alpha (TNF-alpha) with divinyl ether and maleic anhydride copolymer (DIVEMA), which has intrinsic antitumor activity as a synthetic biological response modifier. The degree of modification could be controlled by the addition of 2,3-dimethylmaleic anhydride (DMMAn), which binds to amino groups of TNF-alpha by changing the pH. In addition, the specific activity of DIVEMA-TNF-alpha was hardly decreased in vitro. DIVEMA-TNF-alpha showed a marked antitumor effect compared to native TNF-alpha without any side effects such as sudden death, body-weight reduction, and decrease in platelet count on mice bearing solid tumors. These results suggest that DIVEMA is a useful polymeric modifier for-bioconjugation of TNF-alpha in order to increase its antitumor activity, and multifunctionally bioconjugated TNF-alpha may be a potentiated antitumor agent for therapeutic use.

Cytologic study of ascites and the endometrium in ovarian carcinoma. Clinical significance

OBJECTIVE

To ascertain the usefulness of endometrial cytology with ovarian cancers when examining extension of the disease and to analyze significant factors associated with migration of ovarian cancer cells into the uterine cavity.

STUDY DESIGN

Cytologic results on ascites and the endometrium were analyzed in 87 patients with primary ovarian cancer in the absence of metastasis to the endometrium or cervicovagina.

RESULTS

Positive results for cytology were found in 62/87 of ascites cases (71.3%) and in 20/87 endometrium cases (23.0%). The 15 cases (15/62 or 24.2%) positive for ascitic and endometrial cytology, divided clinically into stage III (6 cases) and stage IV (9 cases), were classified histologically as serous, 7 cases; mucinous, 2 cases; clear cell, 4 cases; endometrioid, 1 case; and unclassified, 1 case. Half the clear cell carcinomas (4/8 or 50.0%) were positive in the ascites and endometrium. The ascitic volume at surgery exceeded 500 mL in 9/15 cases (60.0%).

CONCLUSION

Papillae with basement membrane material in the cores may be structurally associated with migration of ovarian cancer cells into the uterine cavity, especially in clear cell carcinomas. Cytologic positivity of the endometrium and ascites significantly correlated with ascitic volume.

Antibody-based therapy targeting tumor vascular endothelial cells suppresses solid tumor growth in rats

We have developed a new approach to antibody-based therapy of solid tumors by targeting tumor vascular endothelial cells (EC) which are essential for the growth of solid tumors. We investigated the effect of an antibody against tumor-derived endothelial cells (TEC) on the growth of solid tumors in rats. Intravenous administration of TES-23, a monoclonal antibody generated by TEC isolated from rat KMT-17 solid tumors, at 1 mg/rat/day for 5 days resulted in significant suppression of KMT-17 tumor growth. Histopathological analysis of tumors administered with TES-23 showed that adhesion of lymphocytes to EC followed by denudation of EC in the viable tumor area. In contrast, little obvious toxicity was observed in most of the rat organs examined. These findings suggest that the concept of an antibody-based therapy with targeting tumor vascular EC would be promising in treatment of solid tumors.

Pneumoperitoneum complicating mechanical ventilation in congenital myotonic dystrophy

Pneumoperitoneum is known as a disease caused by perforation of the gastrointestinal tract, but it has also been reported as a complication of mechanical ventilation. In a case of congenital myotonic dystrophy (CMyD), mechanical ventilation was performed to treat severe respiratory distress starting at birth, and then pneumomediastinum and pneumoperitoneum developed as complications 5 days after birth. The fact that the pneumoperitoneum improved when the ventilation pressure was reduced and the patient's course was observed, allowed us to rule out gastrointestinal perforation. It appeared that hypoplasia of the diaphragm may have been involved in the progression of pneumomediastinum to pneumoperitoneum in this patient. Mechanical ventilation is performed on many occasions in CMyD, and the development of pneumoperitoneum secondary to pulmonary air leak should always be borne in mind.

Excessive formation of basement membrane substance in clear-cell carcinoma of the ovary: diagnostic value of the "raspberry body" in ascites cytology

Formation of basement membrane-like substance or so-called collagen core was characteristic of clear-cell carcinoma of the ovary in ascites cytology. The hyaline extracellular material was stained light green in Papanicolaou smears and pinkish to purplish red in Giemsa preparations and was frequently observed within the cancer cell clusters in all ten samples of clear-cell carcinoma. Such a structure termed "raspberry body" was focally seen in one of 30 specimens of serous cystadenocarcinoma and one of 30 samples containing reactive mesothelial cells. The "raspberry body" was not found in ascitic fluid from ten patients with mucinous cystadenocarcinoma and two with endometrioid carcinoma. Overproduction of the acidic-charged basement membrane substance was confirmed by 1) cytochemical positivity for periodic acid-Schiff, alcian blue (pH 2.5 or pH 1.0), colloidal iron, and periodic acid-methenamine silver, 2) immunocytochemical demonstration of laminin and type 4 collagen, and 3) ultrastructural identification of excessive formation of the basal lamina. Recognition of the "raspberry body" helps cytopathologists make a cytologic diagnosis of this chemotherapy-resistant malignancy disseminated in ascitic fluid.

Epstein-Barr virus (EBV)-induced CD30+ natural killer cell-type malignancy resembling malignant histiocytosis: malignant transformation in chronic active EBV infection associating hypogammaglobulinemia

A 27-year-old male suffered from Epstein-Barr virus (EBV)-related liver dysfunction with persistent hypogammaglobulinemia. IgG titers to EBV antigens were significantly high, while other hepatitis markers were negative. Liver biopsy disclosed active intralobular inflammation. Two years later, he manifested persistent fever, leukopenia, effusions and hypoproteinemia, and his general condition worsened progressively. The peripheral blood small lymphocytes predominantly expressed natural killer (NK)-like phenotypes (CD2+, CD7+, CD16+, CD56+). Hepatosplenomegaly and marked elevation of serum lactic dehydrogenase were observed. He died of respiratory failure at the age of 29. At autopsy, the liver (2190 g), spleen (860 g), small bowel and mesenteric lymph nodes showed massive infiltration of large atypical lymphoid cells in close association with hemophagocytic histiocytes. Involvement was mildly noted also in the bone marrow, lungs, gall-bladder and kidneys. The atypical cells belonged to CD30+ activated NK-type cells expressing CD2, cytoplasmic CD3 epsilon, CD7, CD45RO, CD56, HLA-DR and HLA-DQ. T cell receptors (TCR), surface CD3, CD4, CD5 and CD8 were not expressed. Epstein-Barr virus-related small nuclear RNA (EBER1) and Epstein-Barr virus-associated nuclear antigen 1 were detected in the nuclei of a significant number of atypical cells, while EBV-related latent membrane protein-1 was negative. EBER1 was also identified in the nuclei of non-neoplastic small lymphocytes at both biopsy and autopsy. Monoclonal integration of the EBV genome into the lymphoma cells was shown by Southern blot analysis. Clonal rearrangement of TCR was undetectable. Roles of chronic active EBV infection in the development of NK cell-type malignancy resembling malignant histiocytosis are discussed.

Subcellular organelle analysis applying confocal laser scanning microscopy to the steroid-producing epithelial ovarian tumor: a technical note

An epithelial ovarian tumor with steroid production was examined in a 70-year-old postmenopausal female. The stromal cells of this tumor were rather dense and occasionally characterized by luteinization or hyperthecosis, which has been associated with steroidogenesis. Subcellular visualization using confocal laser scanning microscopy (CLSM) successfully led to the identification of 3 beta-hydroxysteroid dehydrogenase (HSD) in both mitochondria-like small particles and endoplasmic reticulum-like linear profiles, and P450-aromatase also in endoplasmic reticulum-like linear profiles, on the three-dimensional images.

[Postoperative evaluation of presealed vascular prostheses in surgical treatment of the thoracic aorta]

Two kinds of presealed vascular prostheses were started to use for the thoracic aortic surgery at May 1991. The Gelseal graft was implanted in 13 patients and the Hemashield graft in 31 patients. Each cases was performed enhanced computed tomographic scan periodically to determine the extent of postoperative dilatation of both grafts. These showed that the Gelseal graft is significant more dilated than the Hemashield graft (51.2 +/- 8.1% vs 10.2 +/- 5.8%: p < 0.001). The dilatation was almost completed within one month and no addition later on both grafts. Because of more dilatation and possibility of serous discharge, the Gelseal graft is not good prosthesis for the patients who require postoperative anticoagulant therapy. If the Gelseal graft is used, smaller size should be selected for its dilatation. As the result of this study, the Hemashield graft is more suitable for thoracic aortic lesions than the Gelseal graft.

[Surgical correction of an incomplete endocardial cushion defect in a 66-year-old male with the remarkable pulmonary hypertension]

A surgical case of a 66-year-old male with an endocardial cushion defect (ECD) is reported. He had preoperative pulmonary hypertension (80/25 mmHg, Pp/Ps 0.61), hypoxia (63.7 mmHg) and decreased creatinin clearance (45.7 ml/min). Respiratory condition was New York Heart Association's (NYHA's) grade III. Angiocardiography showed a typical gooseneck deformity associated with mitral and tricuspid valve regurgitations with the cleft (Seller's grade II and III). As surgical correction, direct suture of the cleft in an anterior leaflet with mitral annuloplasty, patch closure of the ostium primum defect with Xenomedical patch and tricuspid annuloplasty were performed. Postoperative data were restored to NYHA grade I. decreased pulmonary artery pressure (43/21 mmHg) and resistances (Pp/Ps 0.36). The only three surgical treatments of an incomplete ECD were reviewed in over 65-year-old patients in Japan included one perioperative death. Although we suggest it should be actively taken surgical repair even in elderly patients with pulmonary hypertension.

A case of epithelioid hemangioendothelioma associated with an artery

We report a case of epithelioid hemangioendothelioma (EHE) arising in the left elbow of a 67-year-old woman. The tumor was characterized by centrifugal growth and association with the brachial artery, causing complete occlusion. Immunohestochemical and electron microscopical features were typical of EHE. The patient was free of local recurrence or disease metastasis for more than 3 years after tumor resection, but subsequently died of respiratory failure due to a primary lung cancer.

[Combined surgery for coronary artery disease and thoracic aortic disease]

Combined surgery in 6 cases who had coronary artery disease and thoracic aortic disease simultaneously was analyzed. Case # 1 had ascending aortic replacement under deep hypothermic circulatory arrest because of iatrogenic aortic dissection caused by aortic clamp during the routine coronary artery bypass grafting (CABG). Case # 2 had DeBakey type II chronic dissection. Case # 3 had type I aortic dissection 4 years after the initial CABG. Both case # 2 and # 3 had ascending aortic replacement under retrograde cerebral perfusion along with CABG. Transverse aortic replacement was performed in case # 4, # 5 and # 6 under selective cerebral perfusion along with CABG. Case # 4 was associated with ascending-transverse aortic aneurysm. Case # 5 had aortitis syndrome complicated with severe coronary ostial stenosis and cervical branch stenosis. Case # 6 also had aortitis syndrome, severe coronary ostial stenosis, heavily calcified ascending-transverse aorta, and mitral and aortic regurgitation. This case had mitral and aortic valve replacement additionally. Case # 2 died of low cardiac output syndrome and multi-organ failure postoperatively. Case # 4 did not recover from profound shock that followed the preoperative acute myocardial infarction. The problems of low cardiac output syndrome caused by long interval of ischemic cardiac arrest, and also the problems of proximal anastomotic site of saphenous vein grafts were discussed.

[A case of ventricular septal perforation treated surgically with an infarction exclusion technique]

We report an 85-year-old woman with postinfarction interventricular septal perforation. She underwent successful emergent surgical treatment by a slightly modified method based on David-Komeda's procedure. Perforation in this case occurred four days after acute myocardial infarction. Preoperative Qp/Qs was 2.58, and pulmonary artery pressure was 34/25 mmHg. The area of infarction was large, and the perforation was the linear type 2.5 cm long near the apex. A probe was not able to pass through the perforation due to its complicated configuration. A double Xenomedica patch was sutured on the left side of the interventricular septum without excising the infarcted area. The suture line was placed on healthy myocardium apart from the infarcted area. The Xenomedica patch was sandwiched between the closure line of the ventriculotomy. Four days after surgery, residual shunt was observed by echocardiogram, but this subsequently disappeared on the 17th postoperative day. The patient was discharged from our hospital on the 57th postoperative day, and is now doing quite well.

PEGylation of interleukin-6 effectively increases its thrombopoietic potency

The in vivo thrombopoietic activity of polyethylene glycol-modified interleukin-6 (MPEG-IL-6), in which 54% of the 14 lysine amino groups of IL-6 were coupled with PEG, was compared to that of native IL-6. Native IL-6 and MPEG-IL-6, which showed about 51% of the specific bioactivity of native IL-6, were administered subcutaneously to mice every 2 days for 7 days. Native IL-6 increased not only the peripheral platelet count, but also the plasma-IgG1 level in a dose-dependent manner. MPEG-IL-6 showed about 500 times higher thrombopoietic potency than native IL-6. Further, in comparison to native IL-6, MPEG-IL-6 did not enhance IgG1 production as much as it enhanced platelet production. MPEG-IL-6 significantly stimulated platelet recovery in mice treated with 5-fluorouracil, whereas the administration of native IL-6 had a negligible effect. The plasma half-life of MPEG-IL-6 was about 100-fold longer than that of native IL-6. The decrease in the plasma clearance of MPEG-IL-6 was thought to be due, in part, to the shielding of the proteolytic sites in the IL-6 molecule by the PEG chain. The uptake of IL-6 by the reticuloendothelial system, such as the liver and spleen, was markedly limited by PEGylation. The PEGylation of IL-6 markedly enhanced the blood-residency of IL-6, resulting in effective augmentation of its thrombopoietic activity and a marked decrease in its side-effects. These findings suggest that MPEG-IL-6 may be a potential candidate for thrombopoietic agent.

Histochemical analysis of hyperplastic stomach of TGF-alpha transgenic mice

Hypertrophic gastric mucosa in transgenic mice overexpressing transforming growth factor (TGF)-alpha showed mucosal cellular hyperplasia with dysplasia, suppression of gastric acid secretion, and chief and parietal cell depletion. In order to clarify the effects of TGF-alpha on the gastric mucosa, we analyzed the stomach of TGF-alpha transgenic mice by mucin histochemical staining and immunohistochemical analysis of TGF-alpha. In transgenic mice, especially those older than 3 months, the fundic gland was notably atrophic but the total mucosa was thickened. The mucous neck cells were hypersecretory and associated with abnormal sulfation. Mucosal hyperplasia was caused by proliferation of surface epithelial cells, associated with formation of intracytoplasmic lumina. The hyperplastic foveolar cells revealed production of a high amount of sialomucin. In addition, the involved stomach regionally revealed collagenous fibrosis in the submucosal layer. The wide distribution of TGF-alpha in the hyperplastic foveolar cells was in sharp contrast to negative expression in the foveolar cells in the control mice. These findings demonstrated the various regulatory functions of TGF-alpha in mucin production, fibrogenesis, and neck cell proliferation in the stomach.

Lecithinization of IL-6 enhances its thrombopoietic activity in mice

This study was conducted to assess the merit of lecithinization of recombinant human interleukin-6 (IL-6) as a drug delivery system. IL-6 was lecithinized by covalently binding it with a phosphatidylcholine (lecithin, PC) derivative. The in-vivo thrombopoietic potency of lecithinized IL-6 (PC-IL-6) was greater than that of native IL-6 when administered subcutaneously, although the in-vitro bioactivity of PC-IL-6 was markedly reduced by lecithinization. When PC-IL-6 and native IL-6 were given in doses that produced the same level of thrombopoietic activity, the former stimulated less production of IgG1, a marker of the adverse effects of IL-6, than did the latter. Furthermore, PC-IL-6 persisted in the blood longer than native IL-6. Based on the above, PC-IL-6 appears to be useful as a drug delivery system and may also be useful in the treatment of drug-induced thrombocytopenia.