Cell surface molecules of human teratoma cell lines

Conventional antisera, monoclonal antibodies and lectins have been used to investigate the cell surface composition of several human teratoma-derived cell lines. This review summarizes our current knowledge obtained from such investigations and uses the information available on murine teratocarcinoma systems as a framework for discussion to compare and contrast the human and murine systems. The potential application of antibodies directed against cell surface molecules in such techniques as in vivo tumour imaging and drug targeting is also discussed.     

Isolation of equine infectious anemia virus glycoproteins. Lectin affinity chromatography procedures for high avidity glycoproteins

Lectin affinity chromatography procedures were evaluated for the isolation of enveloped virus glycoproteins. The major glycoprotein of equine infectious anemia virus (E1AV) bound to concanavalin A (Con A)-Sepharose through interactions which could not be reversed by α-methylglucoside, but elution could be accomplished with buffers containing guanidine hydrochloride or sodium dodecyl sulfate. These denaturants, however, also released about one-half of the Con A protein from the Sepharose matrix. This degradation does not appear to have been recognized previously, as denaturants are frequently employed for the isolation of virus glycoproteins from Con A-Sepharose. In contrast, the virus glycoprotein bound equally well to Sepharose-bound Lens culinaris (lentil) lectin affinity columns and was effectively eluted with buffer containing 0.2 M α-methylglucoside. The lentil lectin-Sepharose procedure described is rapid, inexpensive and results in the efficient separation and recovery of EIAV glycoproteins. Thus, lentil lectin-Sepharose can provide a useful alternative to Con A-Sepharose for isolating other high avidity glycoproteins from viral envelopes or cell membranes.     

Defective functional response to membrane stimuli in lymphocytes from patients with benign prostatic hyperplasia.

Benign prostatic hyperplasia (BPH) is a local disturbance in the prostate that may involve an inflammatory infiltrate predominantly composed of activated lymphocytes and macrophages. The activation and proliferative response of T lymphocytes to different mitogenic signals has been analysed in peripheral blood mononuclear cells (PBMC) from 45 patients with BPH and 55 healthy controls. The PBMC obtained from the patients showed a significant specific impairment in proliferation, CD25 expression and IL-2 production in response to stimulation with lectins (phytohaemagglutinin (PHA), concanavalin A (Con A)), that was not corrected by the addition of IL-2 or of phorbol esters (phorbol myristate acetate (PMA)). Also, the CD28 response was defective in patient PBMC. Activation with anti-CD3 or anti-CD2 MoAbs was normal, but the addition of PMA to these stimuli provoked a significant defective response. Only the use of transmembrane stimuli (PMA and ionomycin) elicited responses similar to those found in the control group. The results indicate that peripheral T lymphocytes from BPH patients show a functional impairment that is mainly explained by an alteration of membrane signals (PHA, CD28) and is distal to protein kinase C (PKC) activation.     

Passive immunization: a method of enhancing the immune response against antigen mixtures

Antigenic competition is known to be a widespread phenomenon when using crude extracts of antigens (e.g., Escherichia coli cytoplasmic proteins) for immunization. This non-specific form of immune suppression can be partially overcome by passive immunization with antibodies against dominant antigens (which are the suppressive molecules) before injection of the antigenic mixture. Blocking these immunodominant antigens or antigenic determinants by a passively administered antibody permits antibody responses against hitherto weakly or non-immunogenic molecules.     

Lectin binding and desmin expression during necrosis, regeneration, and neurogenic atrophy of human skeletal muscle

Changes in the cytoplasm of skeletal muscle fibres during necrosis, regeneration, and neurogenic atrophy have been studied in a wide range of human neuromuscular diseases with a panel of eleven biotinylated lectins and by immunohistochemical staining for the cytoskeletal protein desmin. Increased binding of several lectins was observed in both necrotic and regenerating fibres, with Concanavalin A the most consistently positive lectin. Staining for desmin was strong in the cytoplasm of regenerating and partially damaged fibres and was lost in necrotic fibres, although there were differences in the staining reactions of the two antidesmin antibodies used. In fibres which had undergone neurogenic atrophy, cytoplasmic lectin binding was seen only with Griffonia simplicifolia 1 lectin, and desmin was expressed more strongly than in normal fibres. Lectin binding and immunohistochemical staining from desmin can supplement the information obtained from muscle biopsies by conventional histochemical methods and lead to a better understanding of the mechanisms of muscle damage.     

Galactosylation of N- and O-linked carbohydrate moieties of IgA1 and IgG in IgA nephropathy

The mechanism of IgA deposition in the kidneys in IgA nephropathy is unknown, Mesangial IgA is of the IgA I subclass, and since no consistent antigenic target for the IgA I has been described, we have investigated the glycosylation of the molecule, as a potential non-immunological abnormality which may contribute to its deposition. IgA 1 is rich in carbohydrate, carrying N-linked moieties in common with IgG, but also O-linked sugars, which are rare in serum proteins, and not expressed by IgG or lgA2, Lectin binding assays were designed to examine the expression of terminal galactose on the N-linked carbohydrate chains of purified serum IgG and IgAI, and the O-linked sugars of IgAI and C1 inhibitor (one of the very few other serum proteins with O-linked glycosylation). No evidence was found for abnormalities of N-linked glycosylation of either isotype in IgA nephropathy compared with matched controls. However, in IgA nephropathy, reduced terminal galactosylation of the hinge region O-linked moieties was demonstrated; this was not seen in C1 inhibitor, which showed normal or increased galactosylation of the O-linked sugars. This abnormality of IgA1 has considerable implications for the pathogenesis of IgA nephropathy, since the O-linked sugars lie in an important functional location within the IgA1 molecule, close to the ligand of Fc receptors. Changes in the carbohydrates in this site may therefore affect interactions with receptors and extracellular proteins, leading to anomalous handling of the IgA1 protein in this condition, including failure of normal clearance mechanisms, and mesangial deposition.     

Native and sialic acid masked Lewisa antigen reactivity in medullary thyroid carcinoma

Forty-six medullary thyroid carcinomas (MTC) were subjected to a qualitative and quantitative characterization of native and sialic acid masked Lewis^a (Le^a) antigens. Immunohistochemical investigations included monoclonal antibodies (MABs) directed against alpha(2,3)-sialyl-Le^a, i.e. CA19-9 (MAB 19-9), native Le^a (MAB anti Le^a) and alpha(2,3) sialyl type 1 structure, i.e. CA 50 (MAB C50). To detect sialic acid masked Le^a reactivity, MAB anti-Le^a was also applied to native and enzymatically desialylated tissue sections with and without masking of sialic acid residues by sialic acid and sequence specific lectins. Only 7 MTC (15%) displayed a weak expression of CA19-9, while 16 (33%) showed moderate positive staining for native Le^a. Twenty-seven tumours exhibited a strong staining by the N'ase MAB anti Le^a staining sequence. The latter could most effectively be inhibited by the simultaneous masking of alpha(2,3)-and alpha-(2,6)-linked sialic acid residues due to the comptetitive binding of sialic acid and sequence specific lectins: Maackia amurensis agglutinin (specific alpha(2,3)-linked sialic acid) and Sambucus nigra agglutinin (specific alpha(2,6)-linked sialic acid). Thus, in MTC the major portion of sialic acid masked Le^a antigen reactivity is different from that detected by the MAB 19-9. The antigen reactivity is probably due to Le^a structures containing both alpha(2,3) and alpha(2,6)-linked sialic acid residues. A highly significant correlation between the expression of CA50 and that detected by the N'ase MAB anti-Le^a staining sequence indicates that the alpha(2,3)-sialyl type 1 chain represents a common intermediate structure within the pathway of the biosynthesis of sialylated Le^a antigens, excluding the formation of CA19-9 via the formation of the disialyl type 1 structure. This is subsequently fucosylated to the corresponding sialic acid masked Le^a. Preliminary clinicopathological studies indicate that the sialic acid masked Le^a antigens detected by the N'ase MAB anti-Le^a staining sequence are related to biologically aggressive MTC.     

单纯性肾囊肿的组织起源

目的 探讨单纯性肾囊肿的组织起源。方法 20例囊液标本取自12位男性和8位女性,采用两种方法：（1）测定囊液中钠（Na^ )、钾（K^ )、氯（Cl^-)、尿素氮（BUN）、肌酐（Cr)、葡萄糖（Glu)、总蛋白（TP）等物质的浓度,并与血浆中的浓度相比较;（2）选用两种高选择定位于不同肾小管节段的酶标植物血凝素,四叶莲凝集素和jacalin凝集素,对单纯性肾囊肿标本进行组织化学研究。四叶莲凝集素定位于近端肾小管,而jacalin凝集素定位于远端肾小管和集合管。结果 （1）标本中Na^ 、K^ 、Cl^-、BUN、Cr、Glu的浓度与血浆中浓度基本相等,而血浆中总蛋白的浓度则高于囊液中浓度;（2）15例囊肿内衬上皮的四叶莲凝集素染色均呈强阳性,而jacalin凝集素染色有7例为阴性,另8例为部分弱阳性。结论 单纯性肾囊肿可能起源于近端肾小管。     

Characterization of sugar receptor expression by neoglycoproteins in oral and oropharyngeal squamous cell carcinomas

Recognition of the carbohydrate part of cellular glycoconjugates by sugar receptors like lectins may contribute to biosignaling and interactions between normal and transformed cells. Such recognitions may be essential for establishing phenotypic characteristics in neoplastic cells, including metastasis-associated properties. To evaluate various glycoconjugates in tumor diagnosis and clinical therapy, a panel of 18 biotinylated neoglycoproteins was prepared. This included conjugates of a histochemically inert carrier protein and crucial sugar moieties such as D-glucuronic acid, - and -N-acetyl-galactosamine, -N-acetyl-glucosamine, melibiose, lactose, maltose, cellobiose, mannose, mannose-6-phosphate, fucose, rhamnose, and xylose. In so doing the diazo derivative of the respective p-aminophenyl glycosides was coupled with galactose, (-N-acetyl-galactosamine or -N-acetylglucosamine via an epoxy group-containing aliphatic spacer. Other glycoconjugates used were the proteoglycan heparin and the sulfated fucan fucoidan. Labeling was effected with cyanogen bromide activation and aminoalkylation for specific detection of endogenous sugar receptors, especially lectins. Tissues studied were paraformaldehyde-fixed, paraffin-embedded surgical biopsies from patients with different stages of squamous cell carcinomas (SCCs) of the oral cavity (n = 16) and oropharynx (n = 17), including three lymph node metastases from oropharyngeal primary tumors. Semiquantitative binding differences of probes to tumor stages were evaluated statistically by the Mann-Whitney U-Wilcoxon rank sum W test. Specific binding of a probe to cytoplasmic and nuclear structures was detected with apparent quantitative differences. Overall, the cytoplasmic compartment revealed a higher intensity of histochemical reaction than did nuclear structures, indicating a comparatively higher density of specific carbohydrate receptors. Significant and highly significant two-tailed P values were noted for tissue types and stages of SCCs of the oropharynx but not the oral cavity.