Uptake of Marasmius oreades agglutinin disrupts integrin-dependent cell adhesion

BACKGROUND

Fruiting body lectins have been proposed to act as effector proteins in the defense of fungi against parasites and predators. The Marasmius oreades agglutinin (MOA) is a lectin from the fairy ring mushroom with specificity for Galα1-3Gal containing carbohydrates. This lectin is composed of an N-terminal carbohydrate-binding domain and a C-terminal dimerization domain. The dimerization domain of MOA shows in addition calcium-dependent cysteine protease activity, similar to the calpain family.

METHODS

Cell detachment assay, cell viability assay, immunofluorescence, live cell imaging and Western blot using MDCKII cell line.

RESULTS

In this study, we demonstrate in MDCKII cells that after internalization, MOA protease activity induces profound physiological cellular responses, like cytoskeleton rearrangement, cell detachment and cell death. These changes are preceded by a decrease in FAK phosphorylation and an internalization and degradation of β1-integrin, consistent with a disruption of integrin-dependent cell adhesion signaling. Once internalized, MOA accumulates in late endosomal compartments.

CONCLUSION

Our results suggest a possible toxic mechanism of MOA, which consists of disturbing the cell adhesion and the cell viability.

GENERAL SIGNIFICANCE

After being ingested by a predator, MOA might exert a protective role by diminishing host cell integrity.

Glycoprotein 340 in normal human ocular surface tissues and tear film

The tear film is a complex mixture of secreted fluid, ions, proteins, glycoproteins, and lipids that lubricates and protects the ocular surface. Recently, several antimicrobial peptides have been described in the tear fluid. In this study, we describe the presence of the large secreted glycoprotein gp340 in the tear film. Western blot analysis showed that gp340 is abundant in secreted tears and in the lacrimal glands. Lesser amounts of gp340 were detected in the cornea and conjunctiva. Consistent with Western blot data, reverse transcription-PCR and real-time quantitative PCR showed that gp340 transcripts were abundant in lacrimal gland tissue and were also present in the cornea and conjunctiva. Immunohistochemistry localized gp340 to the acinar cells of the lacrimal gland and the deeper layers of the conjunctival epithelium. gp340 was not detected in conjunctival goblet cells. In the cornea, gp340 was present only in a peripheral band of basal epithelial cells, suggesting that gp340 may play a role in the cycle of corneal epithelial renewal. To determine if tear film gp340 may function as a bacterial agglutinin as it does in saliva, tears were incubated with streptococcal cells and the formation of bacterial aggregates was monitored. Addition of tears to late-exponential-phase Streptococcus mutans cells resulted in time- and dose-dependent aggregation of the bacteria. Furthermore, Western blot analysis confirmed the presence of cell-associated gp340 in isolated bacterial aggregates. The ocular pathogen Staphylococcus aureus, but not Pseudomonas aeruginosa, also aggregated when incubated with tears. These results suggest that gp340 is a normal component of the tear film and that the glycoprotein may function as a bacterial agglutinin.

Fluid- or surface-phase human salivary scavenger protein gp340 exposes different bacterial recognition properties

Salivary scavenger receptor cysteine-rich protein gp340 aggregates streptococci and other bacteria as part of the host innate defense system at mucosal surfaces. In this article, we have investigated the properties of fluid-phase gp340 and hydroxylapatite surface-adsorbed gp340 in aggregation and adherence, respectively, of viridans group streptococci (e.g., Streptococcus gordonii and Streptococcus mutans), non-viridans group streptococci (e.g., Streptococcus pyogenes and Streptococcus suis), and oral Actinomyces. Fluid-phase gp340 and surface-phase gp340 bioforms were differentially recognized by streptococci, which formed three phenotypic groupings according to their modes of interaction with gp340. Group I streptococci were aggregated by and adhered to gp340, and group II streptococci preferentially adhered to surface-bound gp340, while group III streptococci were preferentially aggregated by gp340. Each species of Streptococcus tested was found to contain strains representative of at least two of these gp340 interaction groupings. The gp340 interaction modes I to III and sugar specificities of gp340 binding strains coincided for several species. Many gp340 interactions were sialidase sensitive, and each of the interaction modes (I to III) for S. gordonii was correlated with a variant of sialic acid specificity. Adherence of S. gordonii DL1 (Challis) to surface-bound gp340 was dependent upon expression of the sialic acid binding adhesin Hsa. However, aggregation of cells by fluid-phase gp340 was independent of Hsa and involved SspA and SspB (antigen I/II family) polypeptides. Conversely, both gp340-mediated aggregation and adherence of S. mutans NG8 involved antigen I/II polypeptide. Deletion of the mga virulence regulator gene in S. pyogenes resulted in increased cell aggregation by gp340. These results suggest that salivary gp340 recognizes different bacterial receptors according to whether gp340 is present in the fluid phase or surface bound. This phase-associated differential recognition by gp340 of streptococcal species of different levels of virulence and diverse origins may mediate alternative host responses to commensal or pathogenic bacterial phenotypes.

The putative tumor suppressor deleted in malignant brain tumors 1 is an estrogen-regulated gene in rodent and primate endometrial epithelium

Deleted in malignant brain tumors 1 (DMBT1) is a candidate suppressor of malignancies of the brain, lung, gut, and breast. We have been studying gene expression in the uterus in the presence of estrogens and their antagonists. Here, we show that DMBT1 RNA levels are robustly increased by estrogen treatment in the uteri of ovariectomized monkeys and rats. In monkeys, the progestin antagonist mifepristone inhibits estrogen-dependent uterine proliferation. As determined by a microarray experiment and quantitative analysis of RNA levels, mifepristone inhibited estrogenic induction of DMBT1. DMBT1 was not expressed in intact monkeys that were treated with a gonadotropin agonist to suppress steroidogenesis. An in vitro transfection study with human DMBT1 promoter constructs showed that an Alu site approximately 3000 nucleotides upstream of the gene mediates estrogenic regulation. Surprisingly, the estrogen antagonists tamoxifen, raloxifene, and ICI 182,780 also induced gene expression via this Alu site. Rodents represent a more convenient model system for studying uterine biology than monkeys. In rats, uterine DMBT1 RNA levels were dramatically up-regulated by estrogen. Consistent with the transfection study, tamoxifen and raloxifene increased DMBT1 RNA levels in vivo, but ICI 182,780 inhibited an estrogen-induced increase. Immunohistochemical studies showed that DMBT1 is specifically induced in glandular and luminal epithelia of the rat endometrium. Our experiments establish that DMBT1 is an estrogen-responsive gene with a possible role in endometrial proliferation or differentiation, and they have implications for the putative tumor suppressive and mucosal protective functions of DMBT1 in the uterus.

Directional selection for specific sheep cell antibody responses affects natural rabbit agglutinins of chickens

Agglutination data from generations 8 through 19 indicate that bidirectional selection for specific SRBC antibody responses was successful in a line cross of ISA x Warren medium heavy layers. After 11 generations titers of the high SRBC selected line (H line) were nearly 1:32,000; those of the low SRBC selected line (L line) were less than 1:2, but titers of the randombred control line remained stable at 1:32. Directional SRBC selection also affected levels of a naturally occurring rabbit cell agglutinating antibody (RRBC), presumably the avian form of alpha-galactose antibody (anti-Gal). This indirect response was biphasic and opposite in direction to the SRBC responses through generation 14 after which anti-Gal titers of all 3 lines increased. At generation 19, line H had the highest agglutinin titers; of both types, control line was intermediate, and line L was lowest. The correlation between SRBC and RRBC titers was 0.43 (P = 0.0). Females had higher titers than males, but the difference was only significant for the SRBC antibody (P = 0.028). Qualitative changes in anti-Gal accompanied SRBC selection. Rabbit agglutinins of 4 types were recognizable: classic, granular, annular, and one negative or very weak reaction. The score type means in line L were highest, in the control line were intermediate, and in line H were lowest, suggesting avidity differences now exist among these lines. The results show integration of natural and acquired immune systems because selection for one temporarily affected the other. Given the importance of anti-Gal in primates, our results should stimulate further study of this antibody in poultry species.

The Scavenger Receptor Cysteine-Rich (SRCR) domain: an ancient and highly conserved protein module of the innate immune system

The Scavenger Receptor Cysteine-Rich (SRCR) domain is an ancient and highly conserved protein module of ~100-110 amino acids, which defines a superfamily (SRCR-SF) of either soluble or membrane-bound receptors expressed by hematopoietic and nonhematopoietic cells, at either embryonic or adult stages. The existence of two types of SRCR domains allows the division of the SRCR-SF into two groups. Members of group A contain SRCR domains with 6 cysteine residues and are encoded by two exons, whereas those of group B usually contain 8 cysteines and are encoded by a single exon. Group A members usually present as multidomain mosaic proteins containing single SRCR domains associated to other functional domains, such as enzymatic (protease) domains or collagenous regions. On the contrary, group B members generally present as proteins exclusively composed of tandem repeats of SRCR domains, with or without the presence of CUB and ZP domains thought to be involved in oligomerization but never associated to protease domains. Representatives of either group are found in different animal species, from low invertebrates (sponges) to high vertebrates (mammals). Although no unifying function has been defined for SRCR-SF members, accumulated data, together with the high degree of structural and phylogenetic conservation of SRCR domains indicates that they might subserve basic homeostatic functions, including innate immune defense.

Purification of saliva agglutinin of Streptococcus intermedius and its association with bacterial aggregation and adherence

Streptococcus intermedius strain 1208-1 cells were aggregated in the presence of saliva. The saliva agglutinin was purified by centrifugation, filtration, and gel filtration. SDS-PAGE analyses indicated that the purified agglutinin consisted of two high-molecular-mass proteins. Aggregation was dependent on calcium over pH 5.5, with 1 mM being the most effective concentration. Boiling inactivated purified agglutinin. S. intermedius strain 3 and Streptococcus mutans strain 1 were aggregated in the purified agglutinin. After adsorption with strain 1208-1 cells, the saliva sample did not exhibit any aggregation activity, and the agglutinin bands were no longer visible by SDS-PAGE. Adherence analyses demonstrated that the purified agglutinin immobilized on the surfaces of polystyrene wells, actinomyces cells, and apatite beads accounted for the binding of streptococcus cells. Agglutinin also effectively inhibited adherence to apatite beads coated with native saliva.

Yeast cell-surface display--applications of molecular display

In a cell-surface engineering system established using the yeast Saccharomyces cerevisiae, novel, so-called arming yeasts are constructed that are armed with biocatalysts in the form of enzymes, functional proteins, antibodies, and combinatorial protein libraries. Among the many advantages of the system, in which proteins are genetically displayed on the cell surface, are easy reproduction of the displayed biocatalysts and easy separation of product from catalyst. As proteins and peptides of various kinds can be displayed on the yeast cell surface, the system is expected to allow the preparation of tailor-made functional proteins. With its ability to express many of the functional proteins necessary for post-translational modification and in a range of different sizes, the yeast-based molecular display system appears uniquely useful among the various display systems so far developed. Capable of conferring novel additional abilities upon living cells, cell-surface engineering heralds a new era of combinatorial bioengineering in the field of biotechnology. This mini-review describes molecular display using yeast and its various applications.

Delineation of functional regions within the subunits of the Saccharomyces cerevisiae cell adhesion molecule a-agglutinin

a-Agglutinin from Saccharomyces cerevisiae is a cell adhesion glycoprotein expressed on the surface of cells of a mating type and consists of an anchorage subunit Aga1p and a receptor binding subunit Aga2p. Cell wall attachment of Aga2p is mediated through two disulfide bonds to Aga1p (Cappellaro, C., Baldermann, C., Rachel, R., and Tanner, W. (1994) EMBO J. 13, 4737-4744). We report here that purified Aga2p was unstable and had low molar specific activity relative to its receptor alpha-agglutinin. Aga2p co-expressed with a 149-residue fragment of Aga1p formed a disulfide-linked complex with specific activity 43-fold higher than Aga2p expressed alone. Circular dichroism of the complex revealed a mixed alpha/beta structure, whereas Aga2p alone had no periodic secondary structure. A 30-residue Cys-rich Aga1p fragment was partially active in stabilization of Aga2p activity. Mutation of either or both Aga2p cysteine residues eliminated stabilization of Aga2p. Thus the roles of Aga1p include both cell wall anchorage and cysteine-dependent conformational restriction of the binding subunit Aga2p. Mutagenesis of AGA2 identified only C-terminal residues of Aga2p as being essential for binding activity. Aga2p residues 45-72 are similar to sequences in soybean Nod genes, and include residues implicated in interactions with both Aga1p (including Cys(68)) and alpha-agglutinin.

Purification and characterization of a natural agglutinin in the hemolymph of the prawn Penaeus indicus H. Milne Edwards

A natural agglutinin in the hemolymph of the marine prawn Penaeus indicus was isolated by gel filtration chromatography, purified using polyacrylamide gel electrophoresis, and characterized. Prawn agglutinin has a native molecular mass of 181 kDa and consists of two monomeric units (97 and 84 kDa), maintains some agglutinating activity over a wide pH range (7-9), and is inactivated at 85 degrees C. The agglutinin was denatured upon mixing with trichloroacetic acid, phenol, chloroform, and 45% ammonium sulfate. It was also sensitive to trypsin digestion. The results indicate that prawn agglutinin is proteinaceous in nature, with agglutinating, hemolytic, and antibacterial properties against marine bacteria and erythrocytes with carbohydrate binding sites.

[Effect of Rhizobium leguminosarum 252 agglutinins on the activity of some plant cell enzymes]

The incubation of pea seedling roots with the surface agglutinins R1 and R2 of Rhizobium leguminosarum 252 brought about an increase in the activity of proteases, beta-glucosidase, and, especially, succinate dehydrogenase in the roots. The data presented show that rhizobial agglutinins play an important part in the formation and functioning of legume-rhizobial associations.

Negative regulation of autoreactive B cells in transgenic mice expressing a human pathogenic cold agglutinin

Cold agglutinins (CA) are autoantibodies that bind to erythrocyte carbohydrates at low temperatures and induce complement-mediated cell lysis, thus causing hemolytic anemia. Tolerance mechanisms towards CA-expressing B cells and the factors inducing pathogenic CA production are unknown. In order to develop an animal model for CA disease, we have produced transgenic mice expressing the heavy or the light chain of a human CA, previously shown to be pathogenic to the mouse. Expression of the human H chain alone resulted in a B cell maturation block at the pro-B stage, and did not induce allelic exclusion. In double-transgenic mice, co-expression of the human H and L chains restored B cell development but the majority of bone marrow cells expressing the human IgM were eliminated by deletion. In the periphery, B cells were depleted, and a large proportion of the remaining cells co-expressed a human and a murine H chain, secreting "mixed" IgM. A few autoreactive cells, predominating in the peritoneal cavity, escaped tolerance mechanisms and secreted transgenic IgM. The autoreactive B cells are amenable to polyclonal stimulation, making these transgenic mice a suitable model for a human autoimmune disease.

Revisiting the issue: can the reading for serologic reactivity following 37 degrees C incubation be omitted?

BACKGROUND

Omitting the 37 degrees C reading from screening tests for unexpected antibodies results in failure to detect some Rh, K, and Jk agglutinins of potential significance (wanted positives). However, this measure avoids unwanted positive tests due to cold agglutinins.

STUDY DESIGN AND METHODS

Using data from prior publications, actual risk calculations (ARCs) were made to predict the risk of eliminating the 37 degrees C reading, pretransfusion direct antiglobulin test (DAT), and routine indirect antiglobulin crossmatch (IAT-XM). ARCs used the equation: wanted positives missed x 0.34 (or 0.80) x 5 x percent antigen-positive, where 0.34 = percent of patients transfused (ARCs for 37 degrees C reading and DAT); 0.80 = percent of crossmatched patients transfused (ARCs for IAT-XM); 5 = average number of units transfused. Following elimination of the 37 degrees C reading, the impact of this change on patient care was monitored. Antibody detection and identification data and transfusion reaction reports for 6 months after the change were reviewed. Recently transfused patients with new antibodies were evaluated for immune hemolysis by review of clinical and laboratory data. The findings were compared with those from the same dates of the preceding year.

RESULTS

The risk of transfusing incompatible blood by eliminating the DAT, IAT-XM, and 37 degrees C reading is approximately 1:13,000, 1:2,000, and 1:2,400 units transfused, respectively. The cumulative risk from eliminating all three tests is approximately. 1 :1,000 units. With respect to the 37 degrees C reading, there were no differences between the pre-change and post-change study periods in the incidence of reported transfusion reactions or cases of immune hemolysis associated with newly formed antibodies. However, unwanted positive tests decreased from 162 to 61 following elimination of the 37 degrees C reading. This represents a decrease of 20 percent in the number of samples requiring antibody identification annually.

CONCLUSIONS

Eliminating the 37 degrees C reading from pretransfusion antibody screening tests imposes less risk than omitting the routine IAT-XM, and it avoids the time and costs of evaluating unwanted positive tests, thus reducing expenditures and delays in patient care.

Agglutinin and acidic proline-rich protein receptor patterns may modulate bacterial adherence and colonization on tooth surfaces

Bacterial binding to salivary proteins may in part account for individual differences in the colonization of tooth surfaces. High-molecular-weight glycoproteins, agglutinins, mediate S. mutans adherence, whereas acidic proline-rich proteins mediate adherence of other early-colonizing streptococci and Actinomyces. The aim of the present study was to examine the composition of adherence-related salivary proteins and dental plaque micro-organisms in three individuals with a low, moderate, and high capacity to mediate S. mutans adherence. The S. mutans (strain Ingbritt) binding activity resided with a 300-kDa agglutinin which was six-fold more prevalent in the high S. mutans binding saliva compared with the low one. Binding to all three salivas was completely blocked by a monoclonal anti-agglutinin antibody. The moderate S. mutans binding saliva was found to contain adherence-inhibiting components. Furthermore, the low and moderate S. mutans binding salivas mediated binding of A. naeslundii strain LY7 to a greater extent than the saliva with high S. mutans binding. The A. naeslundii binding activity resided with the acidic proline-rich proteins (APRPs) and paralleled the relative content of 106- and 150-residue APRPs. Low A. naeslundii binding coincided with an almost two-fold higher ratio of 106/150 APRPs compared with the high A. naeslundii binding saliva. During conventional gel filtration, a degradation of the acidic, basic, and glycosylated proline-rich proteins was evident in the saliva with high S. mutans and low A. naeslundii binding. This saliva donor had a comparably high rate of dental plaque formation, high counts of S. mutans, and low counts of other streptococci and Actinomyces.

Salivary parameters of relevance for assessing caries activity in individuals and populations

A review of the non-microbial salivary parameters with respect to their possible association with caries activity is presented. The parameters are limited to those which already are or at least in the near future will obviously be simple enough, also for clinical purposes. Salivary flow rate is undoubtedly the most important single parameter since the cariostatic activity or efficacy of practically all other salivary parameters depends on the flow rate. Flow rate as such has no linear association with dental caries but there seems to exist an individual "threshold" limit which is decisive for enhanced caries activity. This threshold limit varies among different individuals and therefore the so-called normal values for unstimulated or stimulated flow rate are more reliable on a population level than among individuals for screening purposes. In any individual a regular and longitudinal follow-up of the flow rate is of higher clinical value than only a single cross-sectional measurement. Salivary buffer effect has only a weak negative association with caries activity and again, this effect is of greater clinical significance on a population level. Since the decisive processes in caries attack occur within or under the dental plaque, the buffering effect of saliva is limited and obviously more important to screen for erosion-than caries-prone individuals. Although important for dental health, none of the salivary antimicrobial agents as such has shown any strong association with caries activity. The only ones with some evidence of a regulatory role are secretory IgA antibodies, hypothiocyanite ions, and agglutinins. However, the data are controversial and it seems that instead of measuring individual parameters, the assessment of saliva's functional properties (such as the ability to aggregate bacteria, prevent their adhesion to hydroxyapatite or sugar metabolism etc.) is more important for clinical purposes. Of the parameters involved in de- and remineralization process, only salivary fluoride content has some association with caries susceptibility but its diagnostic or predictive value is questionable.

Extensin from suspension-cultured potato cells: a hydroxyproline-rich glycoprotein, devoid of agglutinin activity

Enhanced deposition and cross-linking of hydroxyproline-rich glycoproteins (HRGPs) in the plant cell wall is acknowledged to contribute to the formation of a resistant barrier against pathogen infection. We have isolated, from suspension-cultured potato (Solanum tuberosum L. cv. Desiree) cells, two forms of soluble HRGP, a cross-linked and a monomeric form; the latter can be converted to the cross-linked form by incubation with tomato extensin peroxidase and H2O2. The monomeric form was purified by Sephacryl S-200 gel-filtration, reverse-phase high-performance liquid chromatography and Mono-S cation-exchange chromatography into two isoforms (A, a minor form; B, a major form). The properties of the B isoform were further investigated. A quantitative enzyme-linked immunosorbent assay of the B isoform, using tomato extensin antiserum, showed a titration curve at a high antibody-dilution range comparable to that of purified tomato extension monomer (M.D. Brownleader and P.M. Dey, 1993, Planta 191: 457-469). The amino acid and carbohydrate compositions were similar to those of tomato extensin, but did not match well with the other two HRGPs from potato, potato lectin and potato bacterial agglutinin. These observations demonstrate the similarities of the B isoform to extensin. The homogeneity of the B isoform was demonstrated by its ability to be fully cross-linked in vitro, leaving no residual protein, into a high-molecular-weight form by the action of extensin peroxidase. The trifluoroacetic acid-deglycosylated sample migrated as a single protein band on sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). Moreover, SDS-PAGE and matrix-assisted laser desorption/ionisation-time of flight mass spectrometry indicated a molecular weight of approximately 67 kDa. Circular-dichroism spectroscopy demonstrated that the molecule possess an extended polyproline II helix conformation with no evidence of alpha-helix or beta- sheet secondary structure. In conclusion, we refer to this HRGP as potato extensin. As proposed for other extensins, potato extensin is likely to play a role in cell wall architecture and plant disease resistance.

Saliva-mediated binding in vitro and prevalence in vivo of Streptococcus mutans

The contention that the colonization of oral tissues requires the adhesion of bacteria is undisputed, but adherence can only be studied quantitatively in vitro. It has never been seriously challenged whether the adherence phenomena measured in vitro reflect differences in levels of in vivo colonization. The objective of this study was to investigate the adherence-promoting ability of saliva from persons harbouring Strep. mutans in the range from non-detectable levels to more than 106 colony-forming units/ml. Saliva-mediated adherence of Strep. mutans is promoted by high molecular-weight glycoproteins, agglutinins, which also causes aggregation of the bacteria. Adherence and aggregation of Strep. mutans was investigated individually using parotid saliva from 41 persons. Heavily colonized individuals did not promote adherence better than those with relatively few indigenous bacteria. Aggregation was found to be less rapid with parotid saliva from the heavily colonized individuals (p < 0.05). The results indicate that parotid saliva primarily affects the in vivo prevalence of Strep. mutans by clearing the bacteria from the mouth rather than promoting adherence.

Induction of capacitation in human spermatozoa in vitro by an endometrial sialic acid-binding protein

A Ca(2+)-dependent sialic acid-binding protein (SABP) of human endometrium, which specifically bound to human sperm head plasma membrane in vitro, was found to increase the percentage motility and acrosome-reacted pattern of uncapacitated spermatozoa. The protein was synthesized in the endometrium and secreted into the uterine fluid. This intra-uterine factor, which is apparently advantageous in vitro in inducing human sperm capacitation, may play a significant role in promoting the post-release maturation of ejaculated spermatozoa by enhancing 45Ca uptake into spermatozoa by a pathway which is insensitive to calcium-channel blockers. However, the 45Ca uptake could be enhanced on exposure to the divalent cation ionophore A23187 and inhibited in the presence of the calmodulin inhibitor trifluoperazine. The SABP also induces an increase in intracellular Ca2+ in spermatozoa, as seen by FURA-2 AM studies. Furthermore, overlay studies show human SABP to be a Ca(2+)-binding protein. The data presented here suggest that SABP induces in-vitro sperm capacitation and the subsequent acrosome reaction by increasing intracellular Ca2+ concentration.

Cardiac surgery and cold-reactive proteins

Cold agglutinins are commonly found in sera of healthy persons. They rarely become clinically apparent due to their activity at low temperatures. In these patients, cardiovascular operations requiring hypothermia can result in complications such as hemolysis, renal failure, and myocardial damage and can cause unexpected morbidity and mortality. The literature on cold-reactive proteins is reviewed, and methods of diagnosis and management related to cardiac surgery are suggested. Ideally all patients should be routinely tested preoperatively for the antibodies, and appropriate changes in cardiopulmonary bypass and myocardial management plans should be made in positive patients. Preoperative plasmapheresis may be a useful adjunct, especially in patients requiring operation under profound hypothermia and circulatory arrest. Currently, warm heart surgery appears to be the most expedient method. Unexpected detection of agglutination during operation or hemolysis after operation requires a specific treatment plan.

Binding of host collectins to the pathogenic yeast Cryptococcus neoformans: human surfactant protein D acts as an agglutinin for acapsular yeast cells

Cryptococcus neoformans is an opportunistic pathogen in AIDS patients causing disseminated disease and lethal meningitis after inhalation of acapsular or sparsely encapsulated yeast cells. In this study we have investigated whether a recently described family of primitive opsonins, termed collectins, contribute to innate resistance against C. neoformans. The pulmonary surfactant proteins SP-A and SP-D as well as the serum collectins mannose-binding protein and CL-43 bound in a calcium-dependent manner to acapsular C. neoformans in vitro. Binding was concentration dependent and abolished by competition with defined mono- and oligosaccharides. In contrast, no binding of the collectins was observed with the encapsulated form of the yeast. Furthermore, binding of purified collectin SP-D, but not SP-A, mannose-binding protein, or CL-43, led to a concentration-dependent agglutination of acapsular C. neoformans. These data indicate that collectins recognize carbohydrate structures in the cell wall of an initial infectious form of C. neoformans and may play a role in early antifungal defenses in the lung.

Heteroagglutinins and their significance in baboon hepatic xenotransplantation

The role of preformed xenoreactive antibodies in xenograft recipients is unknown. Humans and baboons possess red cell agglutinating activity associated with isohemagglutinins and heteroagglutinins (HA). We examined the role of HA in two patients who received ABO-identical baboon livers. Human antibaboon HA were assessed by correlating serial titers with studies for rejection. Serial direct antiglobulin testing (DAT) was used to detect baboon antihuman HA, potentially produced by transplanted passenger lymphocytes. Patient 1 survived 70 days. The human antibaboon HA titers remained essentially unchanged from preoperative values. Although hyperacute rejection did not occur, and there was only mild cellular rejection, liver function was suboptimal. Postreperfusion immunoglobulin and complement deposition and histologic changes suggested complement-mediated injury. DAT testing was negative except for passively acquired anti-A from transfusion. At autopsy there was marked bile stasis, but no rejection. Patient 2 survived 26 days with essentially unchanged HA titers until preterminal. Although there was no hyperacute rejection and only mild humoral rejection (without cellular rejection), suboptimal liver function and bile stasis were again noted. Postreperfusion immunoglobulin and complement deposition again suggested complement-mediated injury. DAT testing was negative. At autopsy there was no rejection. Human antibaboon HA do not appear to be associated with hyperacute or cellular rejection, but their role in the complement-mediated injury, suspected in both cases, cannot be definitively excluded. Baboon antihuman HA were not detected in either patient.

Mating type-specific cell-cell recognition of Saccharomyces cerevisiae: cell wall attachment and active sites of a- and alpha-agglutinin

Mating type-specific agglutination of Saccharomyces cerevisiae a and alpha cells depends on the heterophilic interaction of two cell surface glycoproteins, the gene products of AG alpha 1 and AGA2. Evidence is presented with immunogold labelling that the alpha-agglutinin is part of the outer fimbrial cell wall coat. The a-agglutinin is bound via two S-S bridges (Cys7 and Cys50) to a cell wall component, most probably the gene product of AGA1. His273 of alpha-agglutinin has previously been shown to be essential for a- and alpha-agglutinin interaction and a model based on two opposing ion-pairs had been proposed. By site-directed mutagenesis this possibility has now been excluded. With the help of various peptides, either chemically synthesized, obtained by proteolysis of intact glycosylated a-agglutinin or prepared from a fusion protein expressed in Escherichia coli, the biologically active region of a-agglutinin was located at the C-terminus of the molecule. A peptide consisting of the C-terminal 10 amino acids (GSPIN-TQYVF) was active in nanomolar concentrations. Saccharide moieties, therefore, are not essential for the mating type-specific cell-cell interaction; glycosylated peptides are, however, four to five times more active than non-glycosylated ones. Comparisons of the recognition sequences of the S. cerevisiae agglutinins with that of the Dictyostelium contact site A glycoprotein (gp80), as well as with those of the various families of cell adhesion molecules of higher eucaryotes, have been made and are discussed.

Waldenström's macroglobulinemia with an IgM paraprotein that is both a cold agglutinin and a cryoglobulin and has a suppressive effect on progenitor cell growth

BACKGROUND

A patient with Waldenström's macroglobulinemia was admitted to the hospital with fever, leg pain, and dyspnea. The patient had gas gangrene of the left leg that required above-the-knee amputation. Plasmapheresis was instituted to treat hyperviscosity.

STUDY DESIGN AND METHODS

The patient's serum contained an IgM-kappa paraprotein, a cryoglobulin, and a cold agglutinin. The serum was studied.

RESULTS

The patient's red cells typed as A1, Rh-positive. The direct antiglobulin test was negative. The serum contained a cold agglutinin with anti-Pr cold agglutinin specificity (titer 4096). Maximal thermal range was 30 degrees C. Following dithiothreitol treatment, the cold agglutinin activity disappeared. The serum IgM concentration in the tested sample was 62.3 g per L. The cold agglutinin titer in the supernatant after removal of the cryoglobulin was 256, and the IgM level was 0.31 g per L. Redissolving the cryoglobulin in a equivalent volume of saline resulted in a cold agglutinin titer of 4096 and an IgM level of 68.4 g per L. These results indicate that the cryoglobulin and the cold agglutinin are the same paraprotein. Serum protein electrophoresis using agarose gel and immunofixation of the serum revealed an IgM-kappa monoclonal band. Progenitor cell assays were performed by adding the patient's serum at final concentrations of 0, 1, 5 and 10 percent (vol/vol) to patient's and normal donor's peripheral blood mononuclear cells. Inhibition of burst-forming units-erythroid and colony-forming units-granulocyte/macrophage by the patient's serum was demonstrated. Appropriate controls and the use of the serum of another patient with Waldenström's macroglobulinemia did not suppress progenitor cell growth. The patient's serum inhibited colony formation in a dose-response fashion.

CONCLUSION

Reports of cryoprecipitable cold agglutinins are rare. This case is unusual because the IgM-kappa paraprotein was also a cold agglutinin with anti-Pr specificity and erythroid and granulocyte-macrophage progenitor cell-suppressive properties.

[Cold labile serum and plasma proteins: clinical and diagnostic significance of cryoglobulins, cryofibrinogen and cold agglutinins]

Cold labile serum and plasma proteins can cause a variety of clinicopathological symptoms. Due to altered physicochemical properties, cryoglobulins and cryofibrinogens may cause increased serum viscosity, cold dependent protein precipitation or, in rare cases, serum gelification. Cold agglutinins, on the other hand, cause temperature dependent agglutination of erythrocytes and eventually hemolysis. All pathological cold dependent serum and plasma phenomena are associated with either neoplasma, autoimmune disorders, various infections or are considered as "essential". While the diagnosis of these conditions remained largely unchanged during the last 10 years, new aspects regarding etiology, pathogenesis, and therapy have arisen.

Purification and characterization of a Salmonella typhimurium agglutinin from gut mucus secretions

One of the earliest events in Salmonella typhimurium pathogenesis seems to be the interaction of the bacterium with the mucus of the gut. After exposing S. typhimurium to guinea-pig colon, we were able to demonstrate by electron microscopy that S. typhimurium bacteria were trapped on, or in, the mucus layer. Specific components isolated from crude mucus secretions were found to aggregate the bacteria. The degree of bacterial aggregation was dependent on the protein concentration of the crude mucus and on time. Aggregation of S. typhimurium could be abolished by sugars: L-fucose exhibited the strongest inhibition, followed by D-glucose, D-galactose and D-mannose. Lectins were also capable of inhibiting aggregation, the lectin of Ulex europaeus (UEA I), specific for L-fucose, was found to be a stronger inhibitor of bacterial aggregation than Con A. The agglutinin for S. typhimurium isolated from guinea-pig colonic crude mucus preparation was characterized as a 15 kDa glycoprotein. An affinity-purified anti-15 kD antibody inhibited, dose-dependently, the aggregation of S. typhimurium by crude mucus material.

Sexual agglutination in budding yeasts: structure, function, and regulation of adhesion glycoproteins

The sexual agglutinins of the budding yeasts are cell adhesion proteins that promote aggregation of cells during mating. In each yeast species, complementary agglutinins are expressed by cells of opposite mating type that interact to mediate aggregation. Saccharomyces cerevisiae alpha-agglutinin and its analogs from other yeasts are single-subunit glycoproteins that contain N-linked and O-linked oligosaccharides. The N-glycosidase-sensitive carbohydrate is not necessary for activity. The proposed binding domain of alpha-agglutinin has features characteristic of the immunoglobulin fold structures of cell adhesion proteins of higher eukaryotes. The C-terminal region of alpha-agglutinin plays a role in anchoring the glycoprotein to the cell surface. The S. cerevisiae alpha-agglutinin and its analogs from other species contain multiple subunits; one or more binding subunits, which interact with the opposite agglutinin, are disulfide bonded to a core subunit, which mediates cell wall anchorage. The core subunits are composed of 80 to 95% O-linked carbohydrate. The binding subunits have less carbohydrate, and both carbohydrate and peptide play roles in binding. The alpha-agglutinin and alpha-agglutinin genes from S. cerevisiae have been cloned and shown to be regulated by the mating-type locus, MAT, and by pheromone induction. The agglutinins are necessary for mating under conditions that do not promote cell-cell contact. The role of the agglutinins therefore is to promote close interactions between cells of opposite mating type and possibly to facilitate the response to phermone, thus increasing the efficiency of mating. We speculate that they mediate enhanced response to sex pheromones by providing a synapse at the point of cell-cell contact, at which both pheromone secretion and cell fusion occur.

Limited efficacy of leukopoor platelets for prevention of febrile transfusion reactions

Leukopoor red cell components have a reduced incidence of febrile transfusion reactions. An analogous efficacy for leukopoor platelets has not been convincingly established. The authors analyzed the transfusion records of 36 patients (26 women, 10 men) who received leukopoor platelets following febrile reactions to unmodified platelets. These patients received 409 unmodified transfusions (mean/patient 11) with 84 febrile reactions (rate 20.5%). Reaction rates to unmodified, non-HLA-matched single donor platelets (14.0%) and HLA-matched platelets (6.5%) were significantly lower than to pooled concentrates (27.2%) (P less than .01 and P less than .001, respectively). Of 623 leukopoor transfusions (mean/patient 17), 84 resulted in reactions (13.5%). Although leukodepletion significantly lowered the overall reaction rate as compared with unmodified products (P less than .02), a majority of patients (28 of 36) continued to have reactions. When individual reaction rates to unmodified and leukopoor transfusions were compared, only two patients showed a significant decrease in their reaction rate with leukopoor platelets. It appears that most susceptible patients continue to react to leukopoor platelets, particularly when pooled concentrates are used, and many patients show no reduction in reaction rate.

Cyclic AMP enhances the sexual agglutinability of Chlamydomonas flagella

Sexual adhesion between Chlamydomonas reinhardtii gametes elicits a rise in intracellular cAMP levels, and exogenous elevation of intracellular cAMP levels in gametes of a single mating type induces such mating responses as cell wall loss, flagellar tip activation, and mating structure activation (Pasquale, S. M., and U. W. Goodenough. 1987. J. Cell Biol. 105:2279-2292). Here evidence is presented that sexual adhesion mobilizes agglutinin to the flagellar surface, and that this mobilization can be induced by exogenous presentation of cAMP to gametes of a single mating type. It is proposed that Chlamydomonas adhesion entails a positive feedback system--initial contacts stimulate the presentation of additional agglutinin--and that this feedback is mediated by adhesion-induced cAMP generation.

Pseudothrombocytopenia induced by a monoclonal IgM kappa platelet agglutinin

Pseudothrombocytopenia is an in vitro phenomenon usually associated with anticoagulant (EDTA)-dependent IgG platelet agglutinins. A low Coulter platelet count was investigated in a 63-year-old woman with multiple sclerosis and a monoclonal IgM kappa gammopathy. An unusual type of EDTA- and temperature-independent IgM platelet agglutinin was identified by in vitro agglutination of donor platelets and was removed by immunoabsorption.

Influence of monoclonal IgM cold agglutinins on adhesiveness, phagocytosis, and bactericidal activity on human granulocytes and monocytes

Monoclonal IgM cold agglutinins (CA) bind and, in the presence of complement, are cytotoxic to various mammalian cells. The impact of these autoantibodies on functional capacity of phagocytes has not been studied until now. Herein we report that sera with monoclonal IgM anti-I and anti-i CA significantly reduce adhesiveness, phagocytosis, phagocytic index, and intracellular bactericidal activity of human peripheral blood polymorphonuclear cells (PMNs) at 37 degrees C and 24 degrees C. Anti-i CA were more active than anti-I. Sera with monoclonal IgMs without CA activity reduced the total number of ingested bacteria but otherwise had no effect on phagocytic functions. There was no difference in the degree of inhibition when anti-i and anti-I CA were tested against cord, maternal, and adult PMNs. Chromatographically purified a-I and a-i CA inhibited markedly phagocytosis in concentrations as low as 1 mg/ml. Phagocytic activity of peripheral blood monocytes was inhibited by CA at 18 degrees C but not at 24 degrees C or 37 degrees C. Pepsin digestion or reduction and alkylation of chromatographically pure IgM CA abolished completely their inhibitory activity. Thus, in physiological temperatures, monoclonal IgM cold agglutinins impair various phagocytic functions of human phagocytes. It may add to the susceptibility to infections in patients in which such autoantibodies are synthesized.

Hemolytic warm IgM autoagglutinins in autoimmune hemolytic anemia

The authors report a patient with fulminant autoimmune hemolytic anemia due to a rare warm IgM autoagglutinin more reactive at 37 degrees C than at lower temperatures and secondary to systemic lupus erythematosis. The patient's clinical course and the serologic and immunochemical characteristics of the antibody are described, including the possibility that transfusions of small amounts of incompatible red cells may have contributed to the hemolysis. The consequences of using the initial serologic test results as the basis for therapy are discussed.

Identification of glycoprotein components of alpha-agglutinin, a cell adhesion protein from Saccharomyces cerevisiae

Several glycoproteins which inhibit the agglutinability of Saccharomyces cerevisiae mating type a cells were partially purified from extracts of mating type alpha cells. These proteins, called alpha-agglutinin, were labeled with 125I-Bolton-Hunter reagent. The labeled alpha-agglutinin showed specific binding to a cells. Such specific binding approached saturation with respect to agglutinin or cells and was inhibited in the presence of excess unlabeled alpha-agglutinin. Nonspecific binding was similar in a and alpha cells, was neither saturable nor competable, and was three- to fourfold less than the specific binding to a cells at maximum tested agglutinin concentrations. The major a-specific binding species had a low electrophoretic mobility in sodium dodecyl sulfate-polyacrylamide gels and had an apparent molecular weight of 155,000 by rate zonal centrifugation. Endo-N-acetylglucosaminidase H digestion of the purified glycoprotein complex converted the low-mobility material to four major and several minor bands which were resolved by polyacrylamide gel electrophoresis. All but two minor peptides bound specifically to a cells. Analyses of agglutinin from mnn mutants confirmed the deglycosylation results in suggesting that the N-linked carbohydrate portion of alpha-agglutinin was not necessary for activity.

Agglutination of an EDTA blood sample caused by an EDTA-dependent panagglutinin

A novel example of an EDTA-dependent panagglutinin is described. A blood sample drawn into EDTA for a routine hematologic workup demonstrated strong agglutination due to EDTA-dependent panagglutinins. Previous examples have been detected because of discrepant ABO results. This is the first report of an EDTA-dependent panagglutinin that caused agglutination in the EDTA sample collection tube and a false positive direct antiglobulin test.

Spurious automated red cell values in warm autoimmune hemolytic anemia

Two patients with warm autoantibodies to their red cells had a mean cell volume artifactually elevated by red cell agglutination. Red cell size distribution histograms directly showed doublets and triplets of normal-size red cells. This phenomenon is similar to the spurious macrocytosis previously reported due to cold agglutinins, but was not reversible by warming.

Comparison of dose-response curves for alpha factor-induced cell division arrest, agglutination, and projection formation of yeast cells. Implication for the mechanism of alpha factor action

MAT alpha cells of the yeast Saccharomyces cerevisiae produce a polypeptide mating pheromone, alpha factor. MATa cells respond to the pheromone by undergoing several inducible responses: the arrest of cell division, the production of a cell surface agglutinin, and the formation of one or more projections on the cell surface commonly termed the "shmoo" morphology. Dose-response curves were determined for each of these inducible responses as a function of alpha factor concentration. It is shown that under conditions commonly employed in previous studies, the dose-response for cell division arrest is determined by the rate at which cells inactivate the alpha factor. In order to achieve conditions where inactivation would not be the dominant parameter, the cell division response to alpha factor was monitored at low cell densities. Under conditions of essentially no alpha factor destruction, the dose of alpha factor at which cells exhibit a half-maximal response for cell division arrest (2.5 X 10(-10) M) is nearly the same as that at which cells exhibit a half-maximal response for agglutination induction (1.0 X 10(-10) M). On the contrary, the half-maximal response for projection formation was obtained at doses of alpha factor 2 orders of magnitude higher (1.4 X 10(-8) M). These results are consistent with the same high affinity alpha factor receptor mediating both cell division arrest and agglutination induction. A different system of lower affinity must mediate projection formation. Alternatively, if the same system and receptor are used, then a much higher occupancy is required for the induction of projections compared to division arrest and agglutination induction.

Interactions of pseudomonas aeruginosa hemagglutinins with Euglena gracilis, Chlamydomonas reinhardi, and Tetrahymena pyriformis

The galactosephilic and mannosephilic hemagglutinins of Pseudomonas aeruginosa adsorbed onto Euglena gracilis, Chlamydomonas reinhardi, and Tetrahymena pyriformis. Furthermore, peroxidase binding to the 3 protozoan species was shown to be mediated by these lectins. Binding of Pseudomonas lectins to E. gracilis and C. reinhardi caused their specific agglutination, whereas no agglutination was observed with T. pyriformis, even after treatment by papain or by NaF. Added to the culture medium, the Pseudomonas hemagglutins stimulated growth of E. gracilis and T. pyriformis due to their binding to these protozoa; this effect was partly inhibited by the specific sugar.

The role of T-agglutinin in the disappearance of erythrocytes artificially aged by desialylation

The chance discovery of two mouse strains, one with and one without a high presence of serum T-agglutinin, permitted the investigation of the role of this antibody in the disappearance of desialylated erythrocytes, which may be regarded as a model for ageing. The proportional relationship between the quantity of sialic acid removed and the diminution of half-life is not affected by the presence or absence of T-agglutinin. Opsonization by T-agglutinin would therefore appear to be an improbable mechanism. Other possible theories are discussed.