Disintegration of human spermatozoal membranes in seminal plasma decreases the binding capacity of integrins

The in vitro binding capacity of spermatozoal integrins to matrix components after disintegration of sperm membranes was evaluated. The percentage of spermatozoa with functionally-relevant integrins was determined before and after devitalization of spermatozoa, which were resuspended in seminal plasma or in culture medium. The devitalization was performed by cryoshock or by incubation of spermatozoa with triton X-100 in a concentration ranging from 0.01 to 1.0%. The spermatozoal integrins were detected by the binding of anti-integrin antibodies and flow cytometry and the functional activity was monitored by the binding of the spermatozoa to the matrix components in a cell attachment assay. The seminal plasma decreased the binding of anti-integrin antibodies to the spermatozoal surface and the binding of spermatozoa to ligands and matrix components. respectively. In contrast, the expression of fibronectin and laminin on spermatozoa was increased. Not all spermatozoa, which expressed integrins on their surface bound to the ligands in the cell attachment assay. These results suggest that the detectable integrins only partially exert functional relevance. It can be concluded that the spermatozoa with fragile plasma membranes are more prone to functional inactivation of their integrins by the seminal plasma.

A method for monoclonal antibody isotype switching: anti-CD60 VH expression in a heavy chain-deficient hybridoma variant

Alteration of monoclonal antibody isotype is desirable for a variety of purposes, including obtaining an improved reagent for investigative or therapeutic use. A variety of approaches for isotype switching, particularly from IgM to various IgG subclasses, have been described. Antibodies that recognize carbohydrate determinants on glycoproteins, glycolipids, or polysaccharides are generally of the IgM isotype. This includes all available antibodies to the human CD60 antigen, a determinant with cell coactivating properties described on a subset of T lymphocytes and on other cell types. In this report a new method for monoclonal antibody isotype switching is presented. A plasmid containing the VH regions of anti-CD60 linked to C gamma 1 was transfected into a spontaneously arising variant of the CD60 hybridoma that produced kappa light chain but no heavy chain. This transfected hybridoma line maintains stable production of useful quantities of IgG1 monoclonal anti-CD60 in vitro and in vivo.

Partial amino acid sequence and functional aspects of histone H1 proteins in Trypanosoma brucei brucei

Trypanosoma brucei brucei, a protozoan parasite of wild and domestic animals in Africa, is related to the pathogenic agent of human sleeping sickness. Four H1 histone proteins were isolated from nuclei of procyclic culture forms and cleaved with proteases. Amino acid sequence analysis of purified fragments indicated the presence of variants which displayed sequence identities as compared to the C-terminal domain of human H1. Substitutions of amino acids and posttranslational modifications of the histones in T b brucei H1 may influence protein conformation and histone-histone as well as histone-DNA interactions in the chromatin of the parasite. Digestion of soluble chromatin with immobilized trypsin at low and high ionic strengths indicated an internal localization of H1 in the condensed chromatin. The influence of histone H1 of T b brucei on the compaction pattern of the chromatin was investigated by dissociation and reconstitution experiments. Electron microscopy revealed that trypanosome H1 was able to induce condensation of the chromatin of the parasite and of rat liver into dense tangles. After dephosphorylation of H1, 30 nm fibers were induced in rat liver chromatin, while the resulting fibers were distinctly thinner in T b brucei. It can be concluded that the absence of 30 nm fibers in T b brucei chromatin cannot be explained by the divergent variants and posttranslational phosphorylations of H1 only but rather by the influence of both, the divergent core histones, previously described, and H1 properties.

Identity of human extra parotid glycoprotein (EP-GP) with secretory actin binding protein (SABP) and its biological properties

In this paper the identity of the salivary protein EP-GP (extra-parotid glycoprotein) is reported, also apparent in other human secretions. Immunochemical and biochemical analysis demonstrated that EP-GP is similar to the secretory actin-binding protein (SABP), also known as gross cystic disease fluid protein-15 (GCDFP-15) and prolactin-inducible protein (PIP). The molecular mass and charge microheterogeneity of EP-GP, also observed for SABP, was shown to be predominantly caused by the carbohydrate moiety. In addition, evidence was given that EP-GP is not related to the lipocalin Von Ebner's gland protein (human; VEGh). The biological significance of EP-GP and its homologues is not clear. EP-GP bound to actin and fibrinogen as described for SABP and GCDFP-15. However, the affinity for these proteins does not appear to have any direct physiological role in the mucosal secretions. On the other hand, EP-GP binds to several bacteria. By electron microscopy the ultrastructural localization is demonstrated of EP-GP to the cell wall of both Streptococcus salivarius HB and its cell appendage-lacking mutant Streptococcus salivarius HB-C12. Concerning this finding we hypothesize on the possible functional aspects of this enigmatic protein EP-GP.

Coagulation factor XII Locarno: the functional defect is caused by the amino acid substitution Arg 353-->Pro leading to loss of a kallikrein cleavage site

The dysfunctional coagulation factor XII (FXII) Locarno was purified from 2 L of the proposita's plasma. Studies to identify the molecular defect responsible for the lack of amidolytic and proteolytic activity of this FXII variant were performed. Amino acid sequence analysis of peptides obtained from FXII Locarno on activation with either trypsin or plasma kallikrein and dextran sulfate showed an amino acid substitution of Arg 353 by Pro. Thereby, the kallikrein cleavage site at Arg 353-Val 354 is lost. Although trypsin-activated FXII Locarno was fully cleaved at Arg 334-Asn 335 and at Arg 343-Leu 344, neither amidolytic nor proteolytic activity was generated. We conclude that proteolytic cleavage at Arg 343 in the absence of cleavage at Arg 353 is not sufficient to expose the enzymatic active site in FXII Locarno.

Enhanced cytotoxicity of amyloid beta-peptide by a complement dependent mechanism

Amyloid beta-peptide (A beta) has been shown to activate the classical complement pathway in vitro. Here, we demonstrate that this interaction is fully capable of killing cells and damaging cellular processes in mixed hippocampal cultures from embryonic day 18 rat fetuses. Lactic acid dehydrogenase (LDH) release and morphologic changes were used to evaluate toxicity.

[Value of the patient's own test substances in epicutaneous testing]

Patch testing with commercially available test kits of known allergens often leads to detection of the responsible allergen. In many cases, however, the responsible allergen cannot be found unless the patient's "own" products or chemicals are tested. An analysis of 2460 patch tests with patch test kits proposed by the DKG (German Contact Allergy Group) and a positive history of a patient's own substance showed positive results in 208 patients with 289 products. In 44% (129 out of 289) the responsible allergen could only be found by testing the patient's own substances, in 56% (160 out of 289) the same allergen as was responsible for the positive result with patients' endogenous substances was positive in one of the commercially available test kits. The substances that tested positive were medical products/adhesives (45%), cosmetics (39.4%), rubber materials (4.1%), leather materials (0.7%) and others (10%). Subsequent testing of the different components of the patients' own substances that tested positive was carried out in 45 cases and resulted in the detection of new allergens, such as tris-(2-hydroxyethyl)isocyanurate triacrylate. In 27 patients the endogenous substances had tested positive in the course of testing for occupational dermatitis, and in 10 of these positive testing of a patient's own product resulted in notification of an occupational dermatitis. These results show, that patch testing with the patients own products if very important for the finding of the responsible or even new allergens.

[Detection of an unusual varicella zoster virus infection in an immunosuppressed patient with polymerase chain reaction]

We report a case of a 76-year-old patient who developed an atypical form of varicella zoster virus (VZV) reinfection. In addition to histological and serological confirmation of diagnosis, direct demonstration of VZV-DNA was possible by means of the nested polymerase chain reaction. Although VZV infection is usually diagnosed by clinical examination, the nested PCR is a sensitive and specific diagnostic procedure that can be useful especially in atypical cases.

The human 4F2 antigen: evidence for cryptic and noncryptic epitopes and for a role of 4F2 in human T lymphocyte activation

T lymphocyte activation can be triggered through multiple distinct, but functionally related, pathways. Murine monoclonal antibodies (mAbs) have been used to characterize the surface components of several of these pathways, as well as structures whose function is not yet known. One such cell surface structure is the heterodimeric 4F2 antigen, which is expressed on activated and proliferating cells. Two new mAbs that recognize the heavy chain of the 4F2 antigen have been produced in our laboratory. One antibody, UM7F8, is comitogenic with soluble anti-CD2 and immobilized (but not soluble) anti-CD3 mAbs. The second antibody, termed UM2G12, appears to recognize a cryptic epitope on the 4F2 heavy chain and is not comitogenic for T cells. In view of the functional effects seen with UM7F8, and the highly regulated expression of the 4F2 antigen, it seems likely that 4F2 has a specific role in T cell development and activation.

Purification of toxic peptides and the amino acid sequence of CSTX-1 from the multicomponent venom of Cupiennius salei (Araneae:Ctenidae)

The venom of the wandering spider Cupiennius salei was analysed biochemically by gel filtration, cation exchange chromatography, RP-HPLC, IEF, SDS-PAGE and TLC-electrophoresis. The native venom contains high levels of Na+, K+, Ca2+, histamine and taurine. It shows considerable activity of hyaluronidase, but not proteolytic activity. Thirteen peptides (CSTX-1 to CSTX-13) with an apparent mol. wt between 2.6 and 12.5 kDa causing differently strong toxic, effects were purified. Toxicity data of the crude venom (insects and mouse) are given and compared with the toxicity of CSTX-1, which causes most of the crude venom's toxicity. CSTX-1 has a mol. wt of 8352.6 and its amino acid sequence of 74 amino acids is given.

Expression, purification and characterization of the recombinant kringle 2 and kringle 3 domains of human plasminogen and analysis of their binding affinity for omega-aminocarboxylic acids

The kringle 2 (E161T/C162S/EEE[K2HPg/C169S]TT) and the kringle 3 (TYQ[K3HPg]DS) domains of human plasminogen (HPg) were expressed in Escherichia coli in an expression vector with the phage T5 promotor/operator element N250PSN250P29 and the cDNA sequence for a hexahistidine tail to facilitate the isolation of the recombinant protein. A coagulation factor Xa (FXa)-sensitive cleavage site was introduced to remove the N-terminal histidine tag. In r-K2, mutations E161T and C162S were introduced to enhance the FXa cleavage yield and C169S to replace the cysteine residue, participating in the inter-kringle disulfide bridge between kringles 2 and 3. Recombinant proteins were isolated by affinity chromatography on Ni(2+)-nitrilotriacetic acid/agarose and refolded under denaturing and reducing conditions followed by a non-denaturing and oxidising environment. The free thiol group in position 297 in r-K3 was selectively alkylated with iodoacetamide. The hexahistidine tail was successfully removed with FXa. The N-terminal sequence, the amino acid composition and the molecular mass analyses are in agreement with the expected data. The correct arrangement of the disulfide bonds was verified by sequence analysis of the corresponding thermolytic and subtilisin fragments. r-K2 exhibits weak binding to lysine-Bio-Gel. The weak binding affinity of r-K2 for omega-aminocarboxylic acids is confirmed by intrinsic fluorescence titration with 6-aminohexanoic acid (NH2C5COOH) indicating a Kd of approximately 401 microM. In contrast, r-K3 seems to be devoid of a binding affinity for omega-aminocarboxylic acids. Considering earlier determined Kd values of kringle 1, kringle 4 and kringle 5, the binding affinity of HPg kringle domains for NH2C5COOH is proposed to decrease in the following order, kringle 1 > kringle 4 > kringle 5 > kringle 2 > kringle 3.

Kringle solution structures via NMR: two-dimensional 1H-NMR analysis of horse plasminogen kringle 4

The kringle 4 domain of equine plasminogen (ePgn/K4), a close variant of the human homolog (hPgn/K4), contains residues, such as Trp32, which also appear in human apolipoprotein(a) kringle 4-type modules. The ePgn/K4 was investigated as a complex with epsilon-aminocaproic acid, an antifibrinolytic drug, by two-dimensional 1H-NMR spectroscopy at 500 MHz. Secondary structure elements were recognized from sequential medium and long-range dipolar (proton Overhauser) interactions, as well as from the identification of resonances originating from backbone amide protons with slow 1H-2H exchange in 2H2O. Antiparallel beta-sheets, consisting of strands 52-53, 61-65 and 71-75, were identified. Additionally, the segments 14-16 and 20-22 were found to assume characteristic interstrand antiparallel (beta-sheet-like) H-bond pairing. Four type I turns could be identified in strands 6-9, 16-19, 24-27 and 67-70. Ten structures were generated using distance geometry methods, followed by dynamic simulated annealing calculations. The root mean squares deviation of the distances was 2.79 A for all atoms and 1.81 A for backbone atoms only. Hydrogen bridges, involving side chain hydroxyl groups, were identified for Thr16 and Thr65. As observed for the hPgn/K4, the three-dimensional structure of the ePgn/K4 is mainly defined by two antiparallel beta-sheets, 14-16/20-22 and 62-66/71-75, which are oriented perpendicular to each other. Adjacent to these is a hydrophobic pocket, formed by Trp62, Tyr64, Trp72 and Phe74, whose side chains contribute a lipophilic component to the exposed lysine binding site surface. In contrast to the Trp25, Trp62 and Trp72 residues, conserved in the human and equine homologs, the spectrum of the Trp32 side chain reveals an unrestrained, solvent-exposed indole ring.

Semliki Forest virus core protein fragmentation: its possible role in nucleocapsid disassembly

Semliki Forest virus (SFV) envelope proteins function as proton pores under mildly acidic conditions and translocate protons across the viral membrane [Schlegel, A., Omar, A., Jentsch, P., Morell, A. and Kemp, F. C. (1991) Biosci. Rep. 11, 243-255]. As a consequence, during uptake of SFV by cells via receptor-mediated endocytosis the nucleocapsid is supposed to be exposed to protons. In this paper the effects of mildly acidic pH on SFV nucleocapsids were examined. A partial proteolytic fragmentation of core proteins was observed when nucleocapsids were exposed to mildly acidic pH. A similar proteolytic event was detected when intact SFV virions were exposed to identical conditions. Protease protection assays with exogenous bromelain provided evidence that the capsid protein degradation was due to an endogenous proteolytic activity and not to a proteolytic contamination. Detergent solubilization of virus particles containing degraded nucleocapsids followed by sucrose gradient centrifugation led to a separation of capsid protein fragments and remaining nucleocapsids. These data are discussed in terms of a putative biological significance, namely that the core protein fragmentation may play a role in nucleocapsid disassembly.

Evidence of beta 1 integrins and fibronectin on spermatogenic cells in human testis

Interactions between human spermatozoa and oocytes are an essential event in the process of fertilization. Cell-cell and cell-matrix interactions in somatic cells are mediated by adhesion molecules such as beta 1 integrins (very late antigens; VLA). Therefore, we investigated the expression of beta 1 integrins and the matrix proteins collagen IV, fibronectin and laminin in human testis by immunohistology. Monoclonal antibodies against the beta chain of beta 1 integrins reacted with the basement membrane of the tubuli seminiferi, spermatocytes, spermatids and testicular spermatozoa. The alpha 3, -5 and -6 chains of beta 1 integrins showed the same pattern, whereas, the alpha 1, -2 and -4 chains could not be detected on spermatogenic cells. These VLA subunits were localized on endothelial cells, leukocytes and basement membranes. Matrix proteins such as laminin, collagen IV and fibronectin were detectable as components of basement membranes in human testis. Germinal cells except spermatogonia expressed fibronectin only. These results demonstrate that beta 1 integrins and matrix proteins in human testis are normally expressed on somatic tissue and that germinal cells, especially spermatocytes, spermatids and spermatozoa show positive reactions with antibodies against the VLA-3, -5 and -6 complexes and fibronectin. These findings suggest a production of beta 1 integrins and fibronectin during the spermatogenesis and a role of these proteins in adhesive mechanisms of spermatozoa similar to somatic cell-cell or cell-matrix interactions.

Granulocyte activation in bullous diseases: release of granular proteins in bullous pemphigoid and pemphigus vulgaris

BACKGROUND

Eosinophil and polymorphonuclear granulocytes may be involved in the formation of blisters in bullous dermatoses, particularly bullous pemphigoid.

OBJECTIVE

Our purpose was to evaluate the role of granulocyte activation in the pathogenesis of pemphigus vulgaris and bullous pemphigoid.

METHODS

Levels of eosinophil cationic protein (ECP) and neutrophil-derived myeloperoxidase (MPO) in blister fluid and serum and levels of serum IgE were determined in patients with bullous pemphigoid (n = 12), those with pemphigus vulgaris (n = 9) and healthy volunteers (n = 12).

RESULTS

In blister fluid and serum of patients with bullous pemphigoid, significantly elevated concentrations of ECP, MPO and IgE were detected as compared with controls. In contrast, ECP, MPO, and IgE levels in blister fluid and serum of patients with pemphigus vulgaris did not significantly differ from controls. Moreover, the MPO/ECP ratio in serum of patients with bullous pemphigoid was significantly decreased as compared with controls, whereas the MPO/ECP ratio in pemphigus vulgaris did not differ from controls, indicating a preferential activation of eosinophils in bullous pemphigoid only. In patients with bullous pemphigoid, serum levels of ECP and MPO significantly decreased during immunosuppressive therapy to levels similar to those of controls.

CONCLUSION

Activated granulocytes, releasing their granular contents such as ECP and MPO, may be of importance for blister formation in bullous pemphigoid and may be useful for monitoring disease activity.

Beta 1-integrins of spermatozoa: a flow cytophotometric analysis

The expression of adhesion molecules on human ejaculated spermatozoa was investigated by means of flow cytophotometry using monoclonal antibodies against eight different adhesion molecules. Spermatozoa from infertility patients who exhibited normal semen parameters showed specific fluorescence after incubation with antibodies against very late antigens VLA alpha 4, VLA alpha 5, VLA alpha 6, and corresponding matrix proteins laminin and fibronectin. Semen samples from men with teratozoospermia or oligoasthenoteratozoospermia were characterized by reduced expression of adhesion molecules. Normal and pathological semen samples differed mostly in the expression of VLA alpha 5. After artificial induction of the acrosome reaction by a cold shock method and incubation with 2 mM Ca2+, a changed pattern of adhesion molecules on the sperm surface was found for VLA alpha 6 as the most prominent molecule. After treatment of spermatozoa with 0.1% Triton X-100, the number of cells with adhesion molecules increased significantly. This result suggests that adhesion molecules are an integral part of sperm structure.

Lack of HLA-molecules on human spermatozoa and in seminal plasma

The expression of human leukocyte antigens (HLA) on ejaculated spermatozoa and on lymphocytes was compared by flow cytometry using monoclonal antibodies towards HLA class I (pan-HLA-A, -B, -C) and class II (DR) antigens. Soluble antigens of HLA class I (s HLA-A, -B, -C) in seminal plasma and in blood plasma were monitored with an ELISA technique. Lymphocytes showed specific fluorescence after incubation with the antibodies against HLA class I and class II (DR), whereas, on spermatozoa no positive immunofluorescence could be detected. No antibodies were bound to any significant extent either after modifications of sperm preparation (density gradient centrifugation, swim up-technique, addition of azide, foetal calf serum or benzamidine chloride) or after treatment of spermatozoa with detergents. Furthermore, different concentrations of soluble HLA-A, -B, -C in seminal plasma and in blood plasma were detected. The latter one showed soluble HLA about four-fold more concentrated than the seminal plasma (means +/- SD: 262.5 +/- 144.4 nmol l-1 vs. 62.5 +/- 27.1 nmol l-1). These results suggest, that the HLA-expression differs between human spermatozoa and somatic cells.

Biochemical and functional characterization of histone H1-like proteins in procyclic Trypanosoma brucei brucei

Four variants and/or posttranslational modifications of histone H1-like proteins of Trypanosoma brucei brucei procyclic culture forms were extracted with 0.25 N HCl from isolated nuclei and analyzed by two-dimensional gel electrophoresis. The amino acid composition of these proteins, their ability to space nucleosomes regularly and to induce salt-dependent condensation of the chromatin indicated their histone H1 nature. On the other hand, the histone H1-like proteins clearly differed from their higher-eukaryote counterparts by their weak interaction with DNA under low-salt conditions. As a consequence, intact nucleosome filaments were prepared according to a new preparation protocol especially adapted to the unstable chromatin of T. b. brucei. Our results indicate that the biochemical properties of the histone H1-like proteins contribute to the structural and functional differences between the chromatin of procyclic T. b. brucei and that of higher eukaryotes.

Sequence differences between histones of procyclic Trypanosoma brucei brucei and higher eukaryotes

Four histones, a, b, c, d from procyclic Trypanosoma brucei brucei, which show similarities with the amino acid composition of the core histones H3, H2A, H2B and H4, were isolated and cleaved with Endoproteinase Glu-C. The fragments were separated by FPLC reversed phase chromatography and a subset of the fragments (a5, a9, b6, c8, d3, d9, d11) was subjected to sequence analysis. A 54-71% identity was found in the sequences of the fragment c8 and the C-terminal half of H2B and of three fragments of protein d covering the N-terminal half as well as the C-terminal region of H4. The amino acid sequence of the fragment a9 showed a 57 and 54% identity with H3 sequences of Saccharomyces cerevisiae and Xenopus laevis. Neither the a5 nor the b6 sequence could be aligned with histone sequences of other eukaryotes. The significant differences of 21-48% between the T.b. brucei histone sequences and those of calf thymus histones, which are more pronounced than the differences of Tetrahymena pyriformis and the higher eukaryote, resulted partially from replacements of amino acids with different properties and indicate specific patterns of histone-histone and/or histone-DNA contact sites in the nucleosome of T.b. brucei. These differences, together with the lack of a functional histone H1, may be sufficient to explain the lack of a salt-dependent formation of the nucleosome filament into the 30 nm fibre, which reflects alternative methods of organizing and processing the genetic information in the nucleus of the protozoan parasite and which may be of chemotherapeutic significance.