CD34+ circulating progenitor cells after different training programs

Circulating progenitor cells (CPC) are bone marrow-derived cells that are mobilized into the circulation. While exercise is a powerful mediator of hematopoiesis, CPC levels increase, and reports of their activation after different types of exercise are contradictory. Moreover, few studies have compared the possible effects of different training programs on CPC concentrations. 43 physically active healthy male subjects (age 22±2.4 years) were assigned to 4 different training groups: aerobic, resistance, mixed and control. Except for the control group, all participants trained for 6 weeks. Peripheral blood samples were collected through an antecubital vein, and CPC CD34(+) was analyzed on different days: pre-training, post-training, and 3 weeks after finishing the training period. While no significant differences in CPC were observed either within or between the different training groups, there was a tendency towards higher values post-training and large intra- and intergroup dispersion. We detected an inverse linear relationship between pre-training values and % of CPC changes post-training (p<0.001). In the CPC values 3 weeks after training this inverse relationship was maintained, though to a lower extent (p<0.001). No changes in CPC CD34(+) were detected after 6 weeks of different training groups, or after 3 weeks of follow-up.

DNA copy-number abnormalities do not occur in infant ALL with t(4;11)/MLL-AF4

The pathogenesis of infant acute lymphoblastic leukemia (ALL) is still not well defined. Short latency to leukemia and very high concordance rate for ALL in Mixed-Lineage Leukemia (MLL)-positive infant twins suggest that the MLL rearrangement itself could be sufficient for overt leukemia. Attempts to generate a suitable mouse model for MLL-AF4-positive ALL did not thoroughly resolve the issue of whether cooperating mutations are required to reduce latency and to generate overt leukemia in vivo. In this study, we applied single-nucleotide polymorphism array technology to perform genomic profiling of 28 infant ALL cases carrying t(4;11) to detect MLL-cooperating aberrations hidden to conventional techniques and to gain new insights into infant ALL pathogenesis. In contrast to pediatric, adolescent and adult ALL cases, the MLL rearrangement in infant ALL is associated with an exceptionally low frequency of copy-number abnormalities, thus confirming the unique nature of this disease. By contrast, additional genetic aberrations are acquired at disease relapse. Small-segmental uniparental disomy traits were frequently detected, mostly constitutional, and widely distributed throughout the genome. It can be argued that the MLL rearrangement as a first hit, rather than inducing the acquisition of additional genetic lesions, has a major role to drive and hasten the onset of leukemia.

Immunobiological diversity in infant acute lymphoblastic leukemia is related to the occurrence and type of MLL gene rearrangement

The aim of this study was to identify immunobiological subgroups in 133 infant acute lymphoblastic leukemia (ALL) cases as assessed by their immunophenotype, immunoglobulin (Ig) and T-cell receptor (TCR) gene rearrangement pattern, and the presence of mixed lineage leukemia (MLL) rearrangements. About 70% of cases showed the pro-B-ALL immunophenotype, whereas the remaining cases were common ALL and pre-B-ALL. MLL translocations were found in 79% of infants, involving MLL-AF4 (41%), MLL-ENL (18%), MLL-AF9 (11%) or another MLL partner gene (10%). Detailed analysis of Ig/TCR rearrangement patterns revealed IGH, IGK and IGL rearrangements in 91, 21 and 13% of infants, respectively. Cross-lineage TCRD, TCRG and TCRB rearrangements were found in 46, 17 and 10% of cases, respectively. As compared to childhood precursor-B-ALL, Ig/TCR rearrangements in infant ALL were less frequent and more oligoclonal. MLL-AF4 and MLL-ENL-positive infants demonstrated immature rearrangements, whereas in MLL-AF9-positive leukemias more mature rearrangements predominated. The immature Ig/TCR pattern in infant ALL correlated with young age at diagnosis, CD10 negativity and predominantly with the presence and the type of MLL translocation. The high frequency of immature and oligoclonal Ig/TCR rearrangements is probably caused by early (prenatal) oncogenic transformation in immature B-lineage progenitor cells with germline Ig/TCR genes combined with a short latency period.

Donors with positive blood culture: could they transmit infections to the recipients?

A retrospective analysis of data from January 1996 to June 2004 was performed to evaluate the transmission of bacterial infections from organ donors to recipients. Donors were classified according to blood culture results: group 1 with negative blood culture (n = 216), and group 2 with positive blood cultures (n = 52). The age, cause of death, temperature, leukocytes, and number of organs procured were similar in both groups. Donors of group 2 had significantly more days in the intensive care unit (ICU): group 1 (3.14 +/- 3) versus group 2 (4.39 +/- 3.38 days P = .038). Fifty-one percent of group 1 and 52% of group 2 received antibiotic treatment, in most cases because of the suspected presence of a respiratory infection. In 22 donors the organisms that yielded in the blood culture were considered potentially pathogenic/contaminants (subgroup 2A) and in 30 donors the organisms were considered pathogenic (subgroup 2B). The demographic profiles of these two subgroups were similar. During the first month after transplantation, kidney and liver recipients were closely monitored. Recipients received wide-spectrum antimicrobial prophylaxis. Ten of 61 renal recipients developed infectious diseases. In nine cases (four in subgroup 2A and five in subgroup 2B) there were urinary infections. One recipient of subgroup 2B developed prostatitis. Six of 34 hepatic recipients developed infectious diseases. Four of the six cases (four in group 2A and five in group 2B) developed catheter infections and two cases of peritoneal infections. We could not find any case where a bacterial blood isolate from a donor matched a positive culture in the corresponding recipient. A longer stay of a donor in the ICU resulted in the more pronounced growth of organisms in blood cultures, as expected. In our experience, organs obtained from a donor with a positive blood culture may be transplanted safely, probably due to the low virulence of the organisms as well as the polymicrobial therapy routinely given to the recipients.

Ultrastructural description of an unidentified apicomplexan oocyst containing bacteria-like hyperparasites in the gill of Crassostrea rizophorae

Oocysts of an unidentified coccidian are reported in this study to parasitize the gills of the oyster Crassostrea rizophorae (Mollusca, Bivalvia) collected near the city of Recife (Itamaracá Island, 07 degrees 38' 00" S, 34 degrees 48' 06" W), Brazil. Oocysts appeared as light and dense forms, both containing rod-shaped, bacteria-like hyperparasites (BL). Both light and dense oocysts were spherical, 4.3 to 4.7 pm in diameter, but denser oocysts had irregular contours. Both forms consisted of a thick dense wall (approximately 165 nm thick) consisting of 3 layers. The outermost, a dense and irregular layer about 25 nm thick, possessed numerous bead-like structures and some slender conical projections (up to 1.5 microm long). The inner layer of the wall was formed by a dense and homogenous layer about 125 nm thick. Between these 2 layers, a thin light layer about 12 nm thick was present. Uninucleated sporocysts occupied the internal space of the oocyst and contained some rod-shaped BL and mitochondria surrounded by numerous ribosome-like particles. The dense forms of the oocysts showed the same structures described in the lighter forms and appeared to be the final maturation form of the oocysts. Free sporozoites were occasionally observed among oocysts.

Genetic polymorphism of NAD(P)H:quinone oxidoreductase is associated with an increased risk of infant acute lymphoblastic leukemia without MLL gene rearrangements

NAD(P)H:quinone oxidoreductase 1 (NQO1) is a detoxification enzyme that protects cells against oxidative stress and toxic quinones. A polymorphism (C609T) in the gene produces in the heterozygous individuals (C/T) a reduction and in those homozygous for the variant allele (T/T) the abolishment of NQO1 protein activity. To assess whether NQO1 inactivating polymorphism (CT/TT) was a possible risk factor for infant acute lymphoblastic leukemia (iALL), we investigated the distribution of NQO1 genotype in 50 iALL patients, 32 with MLL gene rearrangements (MLL+) and 18 without (MLL-). As controls, 106 cases of pediatric ALL (pALL), and 147 healthy subjects were also studied. Compared to normal controls, the frequency of the low/null activity NQO1 genotypes was significantly higher in the iALL MLL- (72 vs 38%, P=0.006; odds ratio (OR) 4.22, 95% confidence interval (CI) 1.43-12.49), while no differences were observed in iALL MLL+ (44 vs 38%, P=0.553; OR 1.26, 95% CI 0.58-2.74). Similar results were observed when pALL were used as control. Our results indicate that only the iALL patients without MLL rearrangements had a significantly higher frequency of NQO1 genotypes associated with low/null activity enzyme, suggesting a possible role for NQO1 gene as an MLL-independent risk factor, in the leukemogenic process of this subtype of iALL.

A prospective, randomized study in critically ill patients using the Oligon Vantex® catheter

Microbial colonization and the incidence of catheter-related bloodstream infections (CR-BSI) associated with Oligon Vantex silver central venous catheters (CVC) in critically ill patients were determined. A prospective, randomized, controlled 17-month trial was carried out in an intensive care unit (ICU). All patients requiring a triple-lumen CVC for four days or longer were enrolled. Patients were randomized to receive a standard polyurethane CVC or an Oligon Vantex silver CVC. Before removal of the catheter either due to discharge from the ICU or suspected infection, blood for cultures was taken via the CVC and a peripheral site. Skin and hub swabs and catheter-tips were also cultured. Two hundred and six catheters, 103 in both groups, were evaluated. In the control group (CG) 45/103 (44%) and in the silver group (SG) 30/103 (29%) were colonized or had a CR-BSI (P=0.04). The SG was less likely to be colonized than the CG when the catheter remained in situ for eight days or less (P=0.03) or over 15 days (P=0.01); a second or subsequent catheter was present in the same patient (P=0.002), or if the CVC was placed in the internal jugular vein (P=0.05). Multivariate logistic-regression showed predisposing factors for catheter colonization were jugular and femoral sites, second or subsequent catheter, and being a member of the CG. CR-BSI occurred in five cases (four in CG). Rates of CR-BSI per 1000 catheter-days in the CG were 2.8 and in the SG, 0.8 (P<0.001). The Oligon Vantex silver catheter reduced the incidence of catheter-colonization and may decrease the risk of CR-BSI.

Ultrastructural details of the xenoma of Loma myrophis (phylum Microsporidia) and extrusion of the polar tube during autoinfection

Xenomas of the recently described new microsporidian species Loma myrophis parasitizing the gut tissue of the Amazonian fish Myrophis platyrhynchus (family Ophichthidae) were described by light- and transmission-electron microscopy. The xenoma consisted of a thin fibrillar wall that surrounded a hypertrophic host cell cytoplasm containing numerous microsporidian developmental stages and spores. Several spores showed different stages of natural extrusion of the polar tube. Numerous longitudinal and transverse sections of the extruded polar tubes were observed in developing life-cycle stages (spores excepted), the nucleus of hypertrophic host cell, the xenoma wall and surrounding fibroblasts. The extruded polar tubes were projected in all directions with no preferential orientation. These aspects suggested that autoinfection occurred within this xenoma.

Ultrastructural aspects of the myxosporean Henneguya astyanax n. sp. (Myxozoa: Myxobolidae), a parasite of the Amazonian teleost Astyanax keithi (Characidae)

This study reports light and electron microscopical aspects of a myxosporean found in the gills of the freshwater teleost Astyanax keithi Géry, Planquete & Le Bail, 1996 (family Characidae), collected from the estuarine region of the Amazon River, near Belém, Brazil. The prevalence of infection was 23%. In interlamellar spaces of the gills, ellipsoidal whitish cyst-like plasmodia structures were present, which contained spores. The spores had a spermatozoa-like appearance (47.8 +/- 0.71 microm in total length) with a fusiform body (15.2 +/- 0.77 pm in length, 5.7 +/- 0.71 microm in width and 4.2 +/- 0.31 microm in thickness), and each of the 2 valves presented a tapering tail (32.6 +/- 1.11 microm in length). The valves surrounded a binucleate sporoplasm cell and 2 polar capsules (5.0 +/- 0.13 microm in length, 1.5 +/- 0.07 microm in width) that contained 8 to 9 coils of the polar filament. In the sporoplasm, several unique sporoplasmosomes were visible. A synoptic table of spore measurements of known Brazilian Henneguya species is presented. The spores differed from those of previously described species. Based on spore morphology, it is concluded that this species belongs to the family Myxobolidae, genus Henneguya, and that it constitutes a new species: H. astyanax n. sp.

[Transient neurological deficit secondary to a leptomeningeal cyst in an adult patient]

INTRODUCTION

An uncommon complication of fractures of the skull in infancy is a leptomeningeal cyst, which is also known as a growing skull fracture. A post traumatic leptomeningeal cyst may occur in adults, but is much rarer and may be attributed to a fracture of the skull which occurred in childhood. This complication is caused by a tear in the dura mater, through which pulsation of the cerebro spinal fluid forces the arachnoid layer to herniate. The commonest clinical finding is a soft tissue swelling or tumour appearing on the head.

CLINICAL CASE

We report the case of a 47 year old man, with a past history of a head injury in childhood. He presented complaining of loss of sensation in the right arm and deviation of the mouth, from which he recovered within an hour. Neuro imaging studies showed irregular destruction of the right temporal bone and hypodensity of the underlying brain tissue. Surgical operation and histological study of the bone removed showed that it was a leptomeningeal cyst, associated with a cerebral infarct at the site of an old skull fracture.

CONCLUSIONS

A post traumatic leptomeningeal cyst in an adult patient is caused by a tear in the dura mater caused by a skull fracture during childhood. It may be associated with a cerebral infarct. It may present with only transient focal neurological symptoms.

New ultrastructural aspects of the spermatozoon of Aplysia depilans (Gastropoda, Opisthobranchia)

The spermatozoon of the sea hare Aplysia depilans was studied under scanning (SEM) and transmission electron microscopy (TEM). Previous descriptions of this sperm and related species, both from light and electron microscopy, were inconsistent with each other. These descriptions include A. depilans, A. punctata, A. fasciata, A. kurodai and Bursatella leachiplei. Several detailed micrographs provide a new ultrastructural model and reveal new aspects such as the presence of acrosome and the absence of a glycogen piece, therefore the modified dense ring is the terminal structure. Results also show that previous models are incorrect in many aspects. The spermatozoon is a long slender uniflagellated cell with a complex helical structure and a length of approximately 165 microm. Observed in SEM the spermatozoon has an undifferentiated head and tail. The nucleus is cord-shaped and helically intertwined with the axoneme/mitochondrial derivative complex. The mitochondrial derivative has only one glycogen helix. Glycogen presence was demonstrated by Thiéry's method. Typical heterobranchia spermatozoa features are recognised. From bibliographic analysis, a high degree of similarity was found with the sperm of Pleurobranchea maculata (Notaspidea).

Ultrastructure of the microsporidian Inodosporus octospora (Thelohaniidae), a parasite of the shrimp Palaemon serratus (Crustacea, Decapoda)

A parasite of the muscle of the shrimp Palaemon serratus has been examined by light and electron microscopy. Development occurs among myofibrils and induces ultrastructural alterations of the muscle fibers causing white discoloration. This microsporidian is characterized by uninucleate, later diplokaryotic and di-diplokaryotic meronts. The mother cell develops by rosette-like budding into 8 uninucleate sporoblasts, each containing 3 tape-like filaments attached to the wall that is enclosed in a persistent sporophorous vacuole. Each sporoblast gives rise to a uninucleate spore that possesses 3 elongated tape-like filaments attached to the spore wall, like spore tails. The morphological characters of the spores, redescribed in the present study, suggested that the spores belonged to Inodosporous octospora. The possibility that in the future members of Inodosporus sp. may be considered a new parasite group is discussed.

NK cell expression of the killer cell lectin-like receptor G1 (KLRG1), the mouse homolog of MAFA, is modulated by MHC class I molecules

Using a new mAb, 2F1, we characterize a mouse natural killer (NK) cell antigen termed 'killer cell lectin-like receptor G1' (KLRG1; formerly mouse MAFA or 2F1-Ag). KLRG1 is expressed on 30-60% of murine NK cells, and a small fraction of T cells, and is composed of a homodimer of glycosylated 30-38-kDa subunits. Strikingly, cell surface expression of KLRG1 by NK cells was substantially down-regulated in mice deficient for expression of class I molecules, in contrast to the Ly49 lectin-like NK receptors, which are up-regulated in class I-deficient mice. We could not demonstrate binding of KLRG1 to class I molecules in a cell-cell adhesion assay. Transgenic expression of KLRG1 under heterologous transcription elements was unaffected by class I deficiency, indicating that class I molecules do not affect the KLRG1 protein directly, and suggesting that regulation is at the level of expression of the endogenous KLRG1 gene. Evidence is presented that class I molecules regulate KLRG1 via interactions with class I-specific inhibitory Ly49 molecules and SHP-1 signaling. Thus, although KLRG1 and Ly49 molecules are both lectin-like inhibitory receptors that are regulated by class I expression, the effects of class I on the cell surface expression of the molecules are opposing, and the underlying regulatory mechanisms are distinct.

A revised description of Haplosporidium armoricanum, parasite of Ostrea edulis L. from Galicia, northwestern Spain, with special reference to the spore-wall filaments

Haplosporidian spores from Ostrea edulis, previously described as Minchinia armoricana, were reexamined by light and electron microscopy. These spores were either free among host cells or enclosed in sporocysts. They contained two long epispore cytoplasm extensions (ECE), each possessing cytoskeletal structures corresponding to the filaments. After lysis and degradation of the ECE, these extensions disappeared and the spores became devoid of membrane-bound extensions. However, 2 long filaments (approximately 130 microm long) persisted that were closely attached, in opposition to the spore wall, by a bundle of 9-13 fibers each. Thus, we propose a revised description of M. armoricana (= H. armoricana) to confirm its placement in the genus Haplosporidium as H. armoricanum.

A new monoclonal antibody reactive with several Ly49 NK cell receptors mediates redirected lysis of target cells

We produced a novel hamster monoclonal antibody (MAb), 14B11, that recognizes the majority of mouse natural-killer (NK) cells. Transfection studies demonstrated that 14B11 MAb binds a subset of Ly49 receptors, including three putative inhibitory receptors, Ly49F, I, and C. No binding to Ly49A, B, D, or G was detected. In addition, 14B11 was shown to bind the putative activating receptor Ly49H, which required co-transfection of the signaling molecule DAP12 for detectable cell surface expression. Thus, 14B11 is the first reported MAb to bind Ly49H and F. At the functional level, 14B11 MAb enhanced the lysis by IL-2 activated NK cells of an FcR+ target cell line (Daudi), but not an FcR- target cell (EL-4). Because F(ab')2 fragments of 14B11 failed to enhance lytic activity, the enhancement of lysis by intact antibody is apparently due to "redirected lysis," in which stimulatory receptors on the NK cell are bridged by antibody to Fc receptors on the target cell. Cell separation experiments demonstrated that the 14B11-dependent redirected lysis was markedly increased using NK cell populations that had been depleted of Ly49F,+ I,+ or C+ NK cells. Because such depletions are expected to enrich for Ly49H+ NK cells, these results suggest that the enhancement of lysis mediated by 14B11 MAb may be due to stimulation of the activating Ly49H receptor. In conjunction with other anti-Ly49 MAbs, the 14B11 MAb will be useful in further studies of Ly49 receptor function and specificity.

RAS mutations and clonality analysis in children with juvenile myelomonocytic leukemia (JMML)

Juvenile myelomonocytic leukemia (JMML) is a malignant hematopoietic disorder of early childhood with excessive proliferation of the myeloid and monocytic lineage. Deregulation of the RAS signal transduction pathway is thought to play a key role in its pathogenesis. We examined peripheral blood or bone marrow cells of 36 children with JMML for activating point mutations in codons 12, 13 and 61 of the NRAS and KRAS proto-oncogenes by allele-specific restriction assay, single-strand conformation polymorphism and/or direct sequencing. Codons 12, 13 and 61 of HRAS were examined in 26 of these patients. We detected RAS mutations in six cases (17%) located at N12 (n = 2), N13 (n = 3) and K13 (n = 1). In addition, we performed clonality studies on different cell lineages in four of these patients applying the RAS mutation, the karyotype and X-chromosome inactivation patterns as clonal markers. Erythroid cells carried mutant RAS, indicating clonal origin. In EBV B cell lines, one of three patients studied harbored a RAS mutation, while the other two patients had polyclonal B cells with wild-type RAS. T lymphocytes were examined in one patient; they were polyclonal and had wild-type RAS. It is likely that JMML is a heterogeneous disease with respect to clonal involvement of different lineages.

2F1 antigen, the mouse homolog of the rat "mast cell function-associated antigen", is a lectin-like type II transmembrane receptor expressed by natural killer cells

Inhibitory lectin-like receptors expressed on the surface of hematopoietic cells are critically involved in regulation of their effector functions. Here we report that a novel mAb specific for mouse NK cells, 2F1, recognizes the mouse homolog of the mast cell function-associated antigen (MAFA), an inhibitory lectin-like transmembrane receptor expressed on rat mast cells. The 2F1 antigen (2F1-Ag) and rat MAFA are structurally highly conserved and contain a cytoplasmic motif similar to the immunoreceptor tyrosine-based inhibitory motif that is presumably utilized for inhibitory signaling. We also identified a human homolog that is closely related to the rodent MAFA/2F1-Ag proteins. Like rat MAFA, 2F1-Ag is probably encoded by a single gene, which exhibits relatively little polymorphism. Strikingly, while rat MAFA is considered a mast cell antigen, we have been unable to detect cell surface expression of 2F1-Ag by mouse mast cell lines, bone marrow-derived mast cells, or peritoneal mast cells. Furthermore, mouse bone marrow-derived mast cells were devoid of 2F1-Ag mRNA. Instead, we find that approximately 40% of mouse NK cells express 2F1-Ag. Thus, MAFA/2F1-Ag may modulate immunological responses on at least two different cell types bridging the specific and innate immune system.

Prognostic value of minimal residual disease in acute lymphoblastic leukaemia in childhood

BACKGROUND

Sensitive techniques for detection of minimal residual disease (MRD) at degrees of one leukaemic cell per 10(3)-10(6) cells (10(-3)-10(-6)) during follow-up of children with acute lymphoblastic leukaemia (ALL) can provide insight into the effectiveness of cytotoxic treatment. However, it is not yet clear how information on MRD can be applied to treatment protocols.

METHODS

We monitored 240 patients with childhood ALL who were treated according to national protocols of the International BFM Study Group. 60 patients relapsed and the patients in continuous complete remission (CCR) had a median event-free follow-up of 48 months. Bone-marrow samples were collected at up to nine time points during and after treatment. Standardised PCR analysis of patient-specific immunoglobulin and T-cell receptor gene rearrangements and TAL1 deletions were used as targets for semiquantitative estimation of MRD. Amount of MRD was classed as 10(-2) or more, 10(-3), and 10(-4) or less.

FINDINGS

MRD negativity at the various follow-up times was associated with low relapse rates (3-15% at 3 years), but five-fold to ten-fold higher relapse rates (39-86% at 3 years) were found in MRD-positive patients. The distinct degrees of MRD appeared to have independent prognostic value (p [trend]<0.001) at all separate time points, especially at the first two time points (at the end of induction treatment and before consolidation treatment). At these two time points a high degree of MRD (> or = 10(-2)) was associated with a three-fold higher relapse rate when compared with patients with a low degree of MRD (< or = 10(-4)). At later time points (including the end of treatment) even a low degree of MRD was associated with a poor outcome. Positivity in patients in CCR after treatment was rare (< 1%). With the combined MRD information from the first two follow-up time points, it was possible to recognise three different risk groups--55 (43%) were in a low-risk group and had a 3-year relapse rate of only 2% (95% CI 0.05-12%); 19 (15%) were in a high-risk group and had a relapse rate of 75% (55-95%); and 55 (43%) were in an intermediate-risk group and had a 3-year relapse rate of 23% (13-36%).

INTERPRETATION

Our collaborative MRD study shows that monitoring patients with childhood ALL at consecutive time points gives clinically relevant insight into the effectiveness of treatment. Combined information on MRD from the first 3 months of treatment distinguishes patients with good prognoses from those with poor prognoses, and this helps in decisions whether and how to modify treatment.

Specificity, tolerance and developmental regulation of natural killer cells defined by expression of class I-specific Ly49 receptors

Natural killer cells in the mouse express class I MHC-specific inhibitory receptors of the Ly49 protein family. The receptors mediate inhibition of the lysis of tumor cells and normal cells, and mediate the specificity of bone-marrow graft rejection by NK cells in vivo. The function of these receptors may be to confer upon NK cells the capacity to distinguish normal self cells from cells that have down-regulated expression of some or all self-class I molecules. Ly49 receptors discriminate between different class I molecules, and are distributed in expression to overlapping subsets of NK cells. The receptors appear to interact with class I-MHC residues and associated N-glycans, with little or no discrimination of the class I-bound peptide. The Ly49 receptor repertoire may be initially generated by a stochastic process that distributes receptors randomly to different cells and treats the two alleles of a given Ly49 gene independently. However, class I-MHC-dependent "education" processes shape the functional repertoire. The education processes silence potentially auto-aggressive NK cells, probably by ensuring that each NK cell expresses at least one self-specific Ly49 receptor. In addition, NK cell clones that express multiple self-specific Ly49 receptors are disfavored by the education processes, perhaps to confer greater discrimination on to individual NK cells.

Molecular diagnosis of skin relapse in acute lymphoblastic leukemia

Despite improved survival in childhood acute lymphoblastic leukemia (ALL), its recurrence and the recognition of extramedullary dissemination continue to be crucial issues in the management of affected patients. We report the case of a boy with ALL who presented with two skin nodules during maintenance therapy. As histological examination of the routinely stained sections and the study of the immunophenotype of the skin biopsy were not conclusive, molecular analysis was carried out. By means of the heteroduplex analysis of the amplified T cell receptor (TCR) gene products we assessed the clonality of the skin lymphoid infiltrate and showed the same pattern of TCR gamma recombination of the bone marrow at diagnosis. The patient was treated with allogeneic bone marrow transplantation and survives disease-free after 3 years. Since cutaneous relapse in ALL occurs rarely, molecular analysis can be helpful and conclusive in defining the nature of a skin infiltrate.

The effect of thalidomide on the pathogenesis of human immunodeficiency virus type 1 and M. tuberculosis infection

Tumor necrosis factor alpha (TNF-alpha), a cytokine produced during the host defense against infection, is associated with fevers, weakness, and progressive weight loss. Thalidomide inhibits the synthesis of TNF-alpha both in vitro and in vivo and may have clinical usefulness. We therefore initiated a pilot study of thalidomide treatment in patients with human immunodeficiency virus type 1 (HIV-1)-associated wasting with or without concomitant infection with tuberculosis. Thirty-nine patients were randomly allocated to treatment with either thalidomide or placebo in a double-blind manner for 21 days. Thirty-two patients completed the study. In patients with concomitant HIV-1 and tuberculosis infections, thalidomide therapy was associated with a reduction in both plasma TNF-alpha levels and HIV-1 levels. No significant reduction in either TNF-alpha or HIV- 1 levels was observed in patients with HIV-1 infection only. During the study period, patients receiving thalidomide treatment (n=16) showed a significant weight gain (mean +/- SEM: 6.5 +/- 1.2%; p<0.02) relative to placebo-treated patients (n=16). Patients with simultaneous HIV-1 and tuberculosis infections experienced a higher mean weight gain during thalidomide treatment than the group of patients with HIV-1 infection only. The results of this pilot study suggest that thalidomide may have a clinical role in enhancing weight gain and possibly reducing TNF-alpha and HIV-1 levels in patients with HIV-1 and concomitant mycobacterial infections.

Clinical and immune responses of tuberculosis patients treated with low-dose IL-2 and multidrug therapy

The immune response to infection with M. tuberculosis depends on cytokine activation of effector cells. We therefore conducted a pilot study of recombinant human interleukin-2 (rhuIL-2) as an adjunct to multidrug therapy (MDT) to evaluate the safety of this approach and to determine whether IL-2 can enhance the cellular immune response in patients with pulmonary tuberculosis (TB). Patients included in this study presented with a wide range of extent and duration of infection, and were grouped into three categories for data analysis: (1) patients with newly diagnosed, acute-stage TB who were just beginning MDT; (2) patients who had received a minimum of 45 days MDT before the start of the study and who had responded to treatment; and (3) patients with multidrug-resistant (MDR) TB who had been on MDT for at least seven months without apparent beneficial clinical response. Twenty patients received 30 days of twice-daily intradermal injections of 12.5 micrograms of IL-2. Patients from all three groups showed improvement of clinical symptoms over the 30-day period of treatment with IL-2 and MDT. Results of direct smear for acid fast bacilli (AFB) demonstrated conversion to sputum-negative following IL-2 and MDT treatment in all newly diagnosed patients and in 5/7 MDR TB patients. (The size of the skin test response to purified protein derivative (PPD) of tuberculin increased during the 30-day IL-2 adjunctive therapy in newly diagnosed patients, but decreased or disappeared in the other two groups of treated patients.) Assays in vitro for phenotype distribution, natural killer (NK) cell activity, frequency of cells proliferating in response to exogenous IL-2, and antigen-induced blastogenesis demonstrated systemic responses to intradermally administered rhuIL-2. Levels of interferon-gamma (IFN-gamma) in plasma, peripheral blood mononuclear cell (PBMC) IFN-gamma mRNA and IFN-gamma mRNA in biopsy of site of skin test response to purified protein derivative (PPD) were highest in those patients with the most acute symptoms at the beginning of the study, and decreased during rhuIL-2 and MDT. IL-2 immunotherapy did not modify levels of mRNA expression for other cytokines. Patients receiving IL-2 did not experience clinical deterioration or significant side effects. These results suggest that IL-2 administration in combination with conventional MDT is safe and may potentiate the antimicrobial cellular immune response to TB.

Sickle cell anemia and beta-gene cluster haplotypes in Cuba

We have studied 91 patients with SS genotype, 44 children and 47 adults. Excluding the Cameroon and atypical haplotypes, the distribution in the children's sample exhibited 43% Benin, 38% Bantu, and 3% Senegal. In adults, the sample exhibited 46% Benin, 30% Bantu, and 9% Senegal (chi 2: 13.511, 2 df, P = 0.001). When the whole sample of 198 chromosomes (SS, SC, and S/beta thal) is considered, we find that the beta s chromosome is linked 51% to the Benin haplotype, 41% with the Bantu, and 8% with the Senegal. After adjusting for the different frequencies of beta s in Africa, these numbers would predict the port of origin to be 16% from Atlantic West Africa, 37.3% from Central West Africa, and 46% from Bantu-speaking Africa. This is in direct contradiction with the historical record that establishes a higher percentage from Bantu-speaking Africa (55%) and a much lower percentage from Senegal (3.4%). The overall conclusions from these findings is that there is a loss of Bantu haplotypes in sickle cell syndromes in Cuba, particularly among adults, and that there is an excess of Senegal haplotype, also among adults. These differences might reflect the differential survival and severity of the sickle cell disease linked to these haplotypes.

Inhibitory effects of class I molecules on murine NK cells: speculations on function, specificity and self-tolerance

This review addresses the physiological role of class I-mediated inhibition of NK cell lysis. It is suggested that several distinct activating receptors can stimulate NK lysis, all of which can be inhibited by class I molecules on the target cell. Evidence that most or all peptides that bind a class I molecule can cause inhibition is discussed, supporting a model in which NK cells detect loss of class I molecules, rather than loss of specific peptide/class I complexes. Finally, the acquisition of self-tolerance among NK cells is addressed with respect to data suggesting that autoaggressive NK cells are not deleted but rather exhibit altered characteristics which may render them unable to lyse autologous cells.

Multiple natural killer cell-activating signals are inhibited by major histocompatibility complex class I expression in target cells

Several lines of evidence indicate that major histocompatibility complex class I molecules expressed by target cells can prevent natural killer cell (NK) lysis, possibly by engaging inhibitory receptors expressed by NK cells. On the other hand it is likely that NK cells must be activated to lysis by the recognition of unidentified NK target structures on target cells. To investigate the relationship between positive activation of NK cells by NK target structures versus inhibition by target cell class I molecules, we have examined various NK/target cell interactions for which the expression of inhibitory class I molecules by the target cells is known. The results suggests that specific properties of the target cell other than the absence of class I expression are necessary to activate NK-mediated lysis. Furthermore, different effector cell populations, i.e. freshly isolated versus interleukin-2 activated NK cells, differ in their capacity to kill class I-deficient lymphoblast target cells. In general, class I-deficient target cells that are resistant to direct lysis by a given NK population can be lysed by the NK cells when the reaction is mediated by antibody-dependent cellular cytotoxicity (ADCC). Most significantly, all types of NK-mediated lysis of lymphoblasts, of tumor cells and of almost any target by ADCC can be inhibited by appropriate class I gene expression in the target cell. These results suggest a model in which lysis by NK cells must be triggered by any one of a set of distinct target cell ligands, but that all of these signals can be overruled by class I-mediated inhibition.

p53 gene rearrangements in chronic myelocytic leukemia

We performed Southern-blot analysis of the p53 gene in 41 consecutive patients with typical chronic myelocytic leukemia (CML). In two of them, we were able to study cells during both the chronic and the accelerated phases. Only one of the 29 chronic-phase samples had rearrangement of the p53 gene, whereas three of the nine accelerated-phase samples and one of the five patients in blast crisis exhibited rearrangements. Gene deletion was observed in two patients, one in accelerated phase and the other in blast crisis. One patient with a nonrearranged p53 gene in chronic phase showed rearrangement after progression to the accelerated phase. On the other hand, one patient in accelerated phase exhibited rearrangements which disappeared after reversion to chronic phase with successful treatment. Our findings support the opinion that alterations of the p53 gene may play an important role in CML evolution.

[Rearrangement of the bcl1 and bcl2 oncogenes in chronic lymphoid leukemia]

Oncogenes bcl1 and bcl2 are located in the rupture site of t(11;14) and t(14; 18), respectively. They have been found to rearrange in different B-cell malignancies. A molecular study of oncogenes bcl1 and bcl2 was carried out in 42 patients diagnosed of B-cell chronic lymphoid leukaemia. In 14.3% of the patients the rearrangement affected bcl1, but no differences were found with regard to stage and clinical course between these patients and those without any oncogen rearrangement. In all the patients studied bc12 was in a germinal configuration.

[Atypical chronic myeloid leukemia with polymorphism of the BCR gene]

The region of greatest rupture of the gene BCR (M-bcr) was analysed with the restriction enzyme Bgl II plus a molecular probe containing the 5' end of M-bcr in a woman with atypical, Ph'-negative chronic myelogenous leukaemia. An abnormal DNA fragment of 5.0 kb and an extra band were found, suggesting rearrangement. Nevertheless, the use of several restriction enzymes and the addition of a different probe showed the existence of polymorphism with the enzyme Bgl II, which is an unusual finding. These findings stress the usefulness of using different restriction enzymes and molecular probes in the molecular study of chronic myelogenous leukaemia.

Further evidence for the molecular heterogeneity of chronic myeloid leukemia

Cytogenetic and molecular techniques were performed on samples obtained from 29 patients with chronic myelocytic leukemia (CML); 27 were in the chronic phase and two were in blast crisis. A further five cases were also analyzed, two with atypical CML (aCML), one with chronic neutrophilic leukemia (CNL), and two with juvenile CML (JCML). Most of the cases with typical CML were Philadelphia chromosome (Ph) positive and had a rearrangement within the major breakpoint cluster region (M-bcr). One of these cases was shown to be Ph positive but showed no rearrangement within the M-bcr. Two cases with clinical features typical of CML were Ph negative. One of these showed a rearrangement within the M-bcr, but no rearrangement was demonstrated in the other. Both patients in blast crisis were Ph positive and M-bcr positive. One showed a second Ph. Patients with aCML were Ph negative and had no M-bcr rearrangement. A polymorphism within the M-bcr was found with BglII in one case. No Ph chromosome or M-bcr rearrangement was found in CNL or JCML. These data support the molecular heterogeneity reported in CML.

Requirement for sialic acid on neutrophils in a GMP-140 (PADGEM) mediated adhesive interaction with activated platelets

Platelet GMP-140, along with ELAM-1 and gp90MEL, comprise the LEC-CAM family of cell-cell adhesion proteins. The three proteins demonstrate a highly related domain organization, which includes an extracellular calcium-type lectin motif. gp90MEL, a lymphocyte homing receptor, mediates lymphocyte attachment to high endothelial venules of lymph nodes through recognition of a sialylated ligand on the endothelial cells. The rosetting of neutrophils or promyelocytic HL60 cells by activated platelets is mediated by GMP-140 on the platelets. We show here that treatment of neutrophils or HL60 cells with 3 broad spectrum sialidases completely prevents rosetting. However, the Newcastle disease virus sialidase, an enzyme specific for alpha 2,3 and alpha 2,8 linkages of sialic acid does not affect rosetting of HL60 cells. These results indicate that the ligand for GMP-140 requires sialic acid and suggest that an alpha 2,6 linkage may be critical.

Fine structure of zoosporulation in Perkinsus atlanticus (Apicomplexa: Perkinsea)

Light and transmission electron microscopy were used to study different stages of Perkinsus atlanticus (Apicomplexa) during induced zoosporulation, with fluid thioglycollate medium and seawater. Cytokinesis and nucleokinesis of different developmental stages were studied every 12 h during the incubation period of 72 h, at which time the zoospores became free. Uninucleated and flagellated zoospores present the apical complex formed by conoid, polar ring, micronemes, rhoptries and subpellicular microtubules observed at different sections. Ultrastructural details were compared with the other two species of the genus Perkinsus.

Ultrastructural and cytochemical study of spermatogenesis in Scrobicularia plana (Mollusca, Bivalvia)

The ultrastructure of the mature spermatozoa and spermatogenesis of the bivalve Scrobicularia plana are described. Support cells extend from the basal lamina to the lumen of the testis and are laterally connected to the germinal epithelium. Germ cells present intercellular bridges and flagella since the spermatogonial stage. While spermatogonia and spermatocytes appear connected to support cells by desmosome-like junctions, elongated spermatids are held at the acrosomal region by support cell finger-like processes. During spermiogenesis, the acrosomal vesicle differentiates from a golgian saccule and then migrates to the nuclear apex. A microtubular manchette arising from centrioles surrounds the acrosomal vesicle, the nucleus, and the mitochondria at the time these three organelles start their elongation, disappearing after that. The mature spermatozoon of S. plana lacks a distinct midpiece because the mitochondria extend from the region of the pericentriolar complex along the nucleus anteriorly for approximately 1.4 microns. The features of this bivalve type of modified spermatozoon are compared with those of other animal groups having similar modifications.

Ultrastructural and cytochemical observations of the spherites in a parasite trematoda larva

Concentric laminated concretions, termed 'spherites', were found in the parenchymal cells and in the lumen of the collecting vessels of the trematode Meigymnophallus minutus, parasite of a lamellibranch mollusc. In the initial stage, the spherites are surrounded by a membrane and located in close proximity to the endoplasmic reticulum and Golgi complexes, increasing in size with age and by deposit of concentric layers. Later, they migrate and are released into the lumen of the collecting vessels. These structures contain high concentrations of calcium and phosphorus. The organic matrix is mainly composed of protein, lipids, acid phosphatase and glycoproteins as demonstrated by several cytochemical staining methods. It is possible that these calcareous concretions play an important role in the excretory system of the adult trematode, the life cycle of which takes place within the mantle of the host mollusc.