Uneven distribution and size of rabbit lens capsule proteoglycans.

To document the ultrastructural distribution of lens capsule proteoglycans, rabbit lens capsules were fixed and stained overnight in 50 mM sodium acetate, pH 5.6, containing 2.5% glutaraldehyde, 0.2% Cuprolinic Blue and 0.2 M MgCl2. They were rinsed, stained with 1% aqueous sodium tungstate, embedded in Epon, sectioned (60 nm), and examined with an electron microscope at 60 kV. Proteoglycan-Cuprolinic Blue complexes mainly appeared as networks of small electron-dense filaments throughout the posterior and anterior capsules. The posterior capsule was a single layer with a network of small proteoglycan filaments gradually decreasing in size from the humoral side (90 x 10 nm) to the lenticular side (30 x 8 nm). The humoral side of the anterior capsule had a thin lamina (400 nm) containing large (180 x 40 nm), very electron-dense proteoglycan-Cuprolinic Blue complexes plus small proteoglycans. Below this lamina, the complexes were only seen as filaments slightly smaller than those in the corresponding area of the posterior capsule. Cuprolinic Blue binding of the anterior and posterior lens capsules revealed differences in the size and distribution of their sulphated proteoglycans which do not correspond to the patterns of their immunoreactivity with anti-heparan sulphate proteoglycan. The humoral lamina in the anterior capsules, with large proteoglycan structures, might be a distinct structural and functional compartment.

New data on the cytolytic effects of natural killer cells (Kurloff cells) on a leukemic cell line (guinea pig L2C).

L2C leukemia is a leukemia that occurs in strain two guinea pigs. The L2C cells are natural killer-sensitive. The Kurloff cell (KC), a guinea pig NK cell, develops a 3-fold increase in lysosomal enzyme activity and the number of KC cells increases during leukemogenesis, leading to KC cell-mediated L2C cytolysis. This paper shows that conjugates are produced by incubating KC and L2C for 4 h, with 34% of L2C showing chromatin compaction and shrinkage of the cytoplasm. There was also a reorientation of the KC cytoplasmic organelles to face the target cell and an elongation of the KC to produce arms that engulfed the L2C. The L2C had either necrotic or apoptotic characteristics. L2C DNA fragmentation was demonstrated in situ with the comet and the TUNEL assays. 22.2% of the viable L2C lost their membrane asymmetry during KC-L2C conjugation as shown by incubation with Annexin V-FITC. These results provide new evidence that the death of L2C is due, at least partly, to apoptosis. The cytolytic effect of the NKKC might be a model of the cytological changes that occur in NK cell-leukemic cell conjugates.

Ultrastructure of Kurloff body proteoglycans after high pressure freezing, cryosubstitution and postembedding staining with cuprolinic blue.

Very high pressure freezing and cryosubstitution of Kurloff cells preserves the ultrastructural morphology of Kurloff bodies, particularly the myelin figures, as shown by embedding in epoxy resin and conventional postembedding staining. It also preserves the Kurloff body proteoglycans as more expanded spindle-like shapes than does fixation with formaldehyde at atmospheric pressure. But, proteoglycans were not discernible in the Kurloff body matrix on either unstained or conventionally stained thin sections. The Kurloff body skeleton of proteoglycans in their native expanded shape was stained with the electron-dense cationic ministain cuprolinic blue, using thin sections embedded in LR white. The mean equatorial diameter of the spindles was 20-30 nm, while the collapsed filaments produced by aldehyde fixation were about 10-15 nm wide. The spindles were often about 200-300 nm long but could be much longer, depending on the plane of the section. Thus, high pressure freezing, freeze substitution, embedding in LR white, and staining with cationic dyes such as phthalocyanins seems to be a convenient way of visualizing intracellular proteoglycans that are well preserved and in very much like their native expanded state.

Ultrastructure of proteoglycans in the specific granules of guinea-pig basophilic leukocytes as demonstrated by cuprolinic blue staining.

The ultrastructure of sulphate proteoglycans in basophil granules was examined using cytochemical procedures designed to stabilize and visualize these highly anionic macromolecules in situ. Unfixed or glutaraldehyde-prefixed guinea-pig spleen cells were submitted to fixation/staining in 2.5% glutaraldehyde, 0.2% cuprolinic blue (CB; a cationic phthalocyanin dye) and 0.2 or 0.3 M MgCl2 with or without glycosidase treatments. Abundant electron-dense precipitates were present throughout the granule matrix. The stained structures were often arranged in a quasi-crystalline typical banded pattern. Negative control basophils had no electrondense precipitates. Digestion with chondroitinase ABC destroyed the CB-positive electron-dense banded or filamentous patterns while sialidase treatment did not, but led to larger CB-positive filaments in the cytoplasm near the granules. Taking into account their high anionicity, as shown by the stability of dye binding in the presence of 0.3 M MgCl2, and their susceptibility to chondroitinase ABC, the CB-precipitates are assumed to be related to the sulphated proteoglycans previously characterized in basophil granules. The CB-positive crystalline or filamentous network of the granule matrix is also assumed to reflect the in situ location and organization of these intracellular proteoglycans and may be involved in maintaining the shape of the granule.

The proteoglycan skeleton of the Kurloff body as evidenced by cuprolinic blue staining.

This study deals with the ultrastructure of the chondroitin sulphate proteoglycans of the Kurloff body, a large lysosome organelle, metachromatic towards Toluidine Blue, of a blood cell unique to the guinea pig and called the Kurloff cell. Splenic Kurloff cell from oestrogen-treated guinea pig cells were examined after staining with Cuprolinic Blue, a cationic phthalocyanine-like dye, in the presence of MgCl2 in a critical electrolyte concentration method. Better results were obtained when the fixation-staining by the glutaraldehyde Cuprinolinic Blue MgCl2 mixture was preceded by a glutaraldehyde pre-fixation. On light microscopy, Kurloff bodies generally exhibited an overall pink and glassy metachromasia, sometimes with additional darker metachromatic small dots at their peripheries. At the ultrastructural level, the metachromatic central matrix of the Kurloff body usually exhibited, as a major feature, a typical network pattern of ribbon-like or stellate electron-dense precipitates suggesting the presence of a skeleton of Cuprolinic Blue-reactive filamentous structures. Taking into account their high anionicity (as shown by the stability of the dye binding in the presence of 0.3 M MgCl2) and their susceptibility to chondroitinase ABC, these anionic structures were assumed to be related to the proteochondroitin-4-sulphate previously characterized as the only major sulphated glycoconjugate of the Kurloff cell.

Kurloff cell ultrastructure after combined formaldehyde-cetylpyridinium chloride fixation and high-iron diamine staining.

This study deals with the ultrastructure of the chondroitin sulphate proteoglycans of the Kurloff body, a large lysosomal organelle that stains metachromatically with Toluidine Blue and which is present in Kurloff cells (a blood cell unique to the guinea pig). Splenic tissues were fixed with 1% cetylpyridinium chloride (CPC) added to 4% paraformaldehyde and examined either after Spicer's high-iron diamine staining for sulphated anionic sites followed by post-fixation with ferrocyanide-osmium tetroxide or after a simple post-fixation with ferrocyanide-osmium tetroxide. CPC-precipitated sulphated sites were preferentially located at the periphery of the Kurloff body but, unexpectedly, were absent in the central matrix. Although their electron opacity was lower, these anionic sites were readily observable in the absence of HID-staining after sole post-fixation by ferrocyanide-reduced osmium. CPC-precipitated sulphated anionic sites were either associated with the myelin figures or constituted unexpected structures. They contained (i) tightly-stacked lamellae, with a very regular 4 nm periodicity, and (ii) groups of 2, 3, 4 short dense lines with a 3-5 nm periodicity. By taking into account the susceptibility of these HID-reactive structures towards chondroitinase ABC, these different sulphated components were assumed to be related to the proteochondroitin-4-sulphate previously characterized as the only major sulphated glycoconjugate of the Kurloff cell. Their colocalization with phospholipidic structures was suggested following observation of sections treated by a chloroform-methanol mixture.

Collagen-associated sulphated proteoglycans. Ultrastructure after formaldehyde-cetylpyridinium chloride fixation.

In the course of an ultrastructural cytochemical study of intracellular sulphated proteoglycans involving the addition of cetylpyridinium chloride in the primary aldehyde fixative, a remarkable ultrastructural preservation of the collagen-associated sulphated proteoglycans was observed. Together with the preservation of their localization among the collagen fibrils (with, for some of them, a 50 nm periodic association with d-bands) and of their native elongated shape, previously observed under similar technical conditions, these stick-shaped and chondroitinase ABC-sensitive proteoglycans exhibited a typical pattern with several dense longitudinal parallel tracks (periodicity: 3-4 nm) not described as yet. Readily observable without high iron diamine-staining, the morphology of these cetylpyridinium chloride-precipitated and collagen-associated polyanions was particularly enhanced after incubation in the diamine solution which ascertained their sulphate content. Such a common ultrastructural organization with parallel tracks for both intracellular (i.e., in eosinophilic polymorphonuclear cells and Kurloff cells) and extracellular CPC-precipitated sulphated proteoglycans could correspond to intrinsic properties of the complexed molecules and could be related to 'double track' proteoglycans observed under other technical conditions in basement membranes.

Natural killer activity of Kurloff cells: a direct demonstration on purified Kurloff cell suspensions.

In order to study their natural killer effect, guinea pig splenic Kurloff cells were fractionated by Percoll discontinuous density gradient centrifugation. Kurloff cells were collected and tested for cytotoxicity in a 24-hr chromium-release test. Comparison of different splenic cellular samples (of males or estrogenized females) with increasing percentage of Kurloff cells, revealed a highly significant positive correlation (r = 0.93, alpha less than 0.01) with the cellular cytotoxicity developed against the K 562 target cells.

Isolation of Kurloff cells by Percoll density gradient centrifugation. Protein labeling with 35S-methionine of these cells.

Large populations of splenic Kurloff (150 - 200 X 10(6) Kurloff cells) were obtained from estrogenized guinea pigs by isopycnic centrifugation in a Percoll solution of 1.085 g/ml starting density. The Kurloff cells settled at a buoyant density of about 1.100 g/ml. The purity of these cell suspensions reached 95%, as assessed by phase contrast microscopy and by specific staining. The viability assessed by Trypan blue exclusion test was also about 95%. Moreover, the good transmission electron microscopic appearance of these Kurloff cells and their ability to take up 35S-methionine in culture confirmed their physiological integrity. By autohistoradiography, this protein labeling was localized between the nucleus and the Kurloff body, and also on the Kurloff body itself. This data reinforces the hypothesis of de novo synthesis of the Kurloff body.

[Increase in the number of Kurloff cells following estrogen stimulation in guinea pigs: demonstrated latency period]. / Augmentation du nombre des cellules de Kurloff après stimulation oestrogénique chez le cobaye: mise en évidence d'un temps de latence.

The comparative study between plasma estradiol levels and KURLOFF cell numbers in the blood and some organs of adult, non pregnant female guinea-pigs, leads us to describe a biphasic response of the KURLOFF cells to estrogen stimulation. The first step, a five day lag-phase, is followed by a secondary increase of KURLOFF cell numbers with a peculiarly noticeable storage in the thymus parenchyma.

Scanning electron microscopy of pure Kurloff cell suspensions. Observation of an extrusion process.

Scanning electron microscopy has been used to examine suspensions of Kurloff cells, which are present only in guinea pig. The cells are round with a surface characterized by uniformly distributed short stubby microvilli and some ridges. Some cells show one or more pores surrounded by a smooth margin, others a smooth globular expansion about 10 microns in diameter which may correspond to a Kurloff body undergoing exocytosis. The Kurloff body is released into the medium where it can exist freely. The surface of the free body and of the expansion display the same smooth appearance. Although the nature of the Kurloff cell remains unknown, this study provides further information concerning its morphology and describes an extrusion process not observed previously.

Fibrinogen or its derivatives in the Kurloff cells.

We have investigated the occurrence of fibrinogen or its derivatives in the Kurloff bodies of female guinea pigs by means of immunofluorescence, histochemistry and ultrastructural analysis. The Kurloff bodies are fluorescent after incubation with anti-guinea pig fibrinogen immuno-globulins coupled with fluorescein isothiocyanate. PTAH, Martius scarlet blue, Masson 44--41, Picro-Mallory V stain the Kurloff bodies just as they stain fibrin and fibrinoid. However, the ultrastructure of the central mass of the Kurloff body is finely granular without fibrils. Thus the Kurloff body contains no fibrin but incompletely polymerized fibrinogen derivatives or breakdown products of fibrin.

Red cell and white cell counts in adult female guinea-pigs.

We made red cell and white cell counts in an homogeneous sample of more than 250 healthy, non gravid, adult, female guinea-pigs. Up to the present it is the highest number of guinea-pigs on which systematic blood counts have been taken. Each category of cells was studied statistically. Our mean of the red cells (5.03 X 106/mm3) is close to most of the means reported in the literature for both sexes; the distribution apparently follows the Gauss normal distribution. The mean of the white cells that we obtained (11.800/mm3) is greater than those of many authors in both sexes. The total number of lymphocytes and monocytes (6.180/mm3) is larger than that of the granulocytes (4.970/mm3). The mean Kurloff cells is 422/mm3. The distribution curves of the aggregate of white cells and those of the granulocytes, the lymphocytes and monocytes, the Kurloff cells are asymmetrical and spread towards the right; the normality hypothesis is rejected for each of them.

The Kurloff cell. Its differentiation in the blood and lymphatic system.

Kurloff cells belong to the group of macrophages as far as ultrastructure, adhesiveness and identification with Kupffer cells (in the case of the liver) are concerned. A characteristic group of features makes it easy to recognize them: PAS reaction, cyanol-blue staining, presence of myelin figures in electron microscopy and attachment to glass-slides. Kurloff cells are thymic and blood cells. They are observed in small numbers in the circulating blood and, in large quantities, in spleen (red pulp), liver (hepatic sinusoids) and lung (septal capillaries). They are absent from lymphatic nodules and from diffuse lymphatic tissues. Morphological and experimental studies indicate that, in spite of some equivocal similarities, Kurloff cells are distinguishable by many criteria from erythrophagocytic cells and from protein-secreting blood cells.