High fidelity simulation in Spain: from dreams to reality

Clinical simulation has emerged as a powerful new tool for the learning and assessment of different skills and attitudes in patient care, by using innovative technology such as high fidelity simulators (HFS).

OBJECTIVE

To describe the current state of high fidelity clinical simulation in Spain and its principal characteristics.

METHODS

Descriptive observational study that analyzes information on the clinical centers that have HFS in our country.

RESULTS

There are currently a total of 80 centers with HFS in our country, mainly distributed in university centers (43), hospital and emergency centers (27), simulation centers and institutes of simulation (5), and the rest (5) associated to entities of diverse ownership. The temporal development of HFS has been slowly progressive, with a significant growth in the last 6 years. The majority (74%) have specific facilities, auxiliary equipment (60%), and professionals with a shared commitment (80%). It is already integrated into the training programs in 56% of university centers with HFS.

CONCLUSIONS

The development of HFS has been remarkable in our country, and is mainly related to university undergraduate and postgraduate clinical medical education. It would be useful to design a network of simulation training centers of Health Sciences in Spain, which would be operational, sustainable and recognized, to optimize the use of these facilities.

Properties of capsaicinoids for the control of fungi and oomycetes pathogenic to pepper

Capsaicinoids are pungent compounds found in pepper (Capsicum spp.) fruits. Capsaicin showed antimicrobial activity in plate assays against seven isolates of five species of fungi and nine isolates of two species of oomycetes. The general trend was that oomycetes were more inhibited than fungi. Assays of capsaicin biosynthetic precursors suggest that the lateral chain of capsaicinoids has more inhibitory activity than the phenolic part. In planta tests of capsaicinoids (capsaicin and N-vanillylnonanamide) applied to the roots demonstrated that these compounds conferred protection against the pathogenic fungus Verticillium dahliae and induced both chitinase activity and expression of several defence-related genes, such as CASC1, CACHI2 and CABGLU. N-Vanillylnonanamide infiltrated into cotyledons confers systemic protection to the upper leaves of pepper against the fungal pathogen Botrytis cinerea. In wild-type tomato plants such cotyledon infiltration has no protective effect, but is effective in the Never-ripe tomato mutant impaired in ethylene response. A similar effect was observed in tomato after salicylic acid infiltration.

Distribution of lignin monomers and the evolution of lignification among lower plants

Through application of chemical, biochemical and histochemical analyses, we provide new data on the absence/presence of syringyl lignins in the algal species Mastocarpus stellatus, Cystoseira baccata and Ulva rigida, the bryophytes Physcomitrella patens and Marchantia polymorpha, the lycophytes Selaginella martensii, Isoetes fluitans and Isoetes histrix, the sphenophyte Equisetum telmateia, the ferns Ceratopteris thalictroides, Ceratopteris cornuta, Pteridium aquilinum, Phyllitis scolopendrium and Dryopteris affinis, and the angiosperm Posidonia oceanica. Lignins, and especially syringyl lignins, are distributed from non-vascular basal land plants, such as liverworts, to lycopods and ferns. This distribution, along with the already reported presence of syringyl lignins in ginkgoopsids, suggests that syringyl lignin is a primitive character in land plant evolution. Here, we discuss whether the pathway for sinapyl alcohol recruitment was iterative during the evolution of land plants or, alternatively, was incorporated into the earliest land plants and subsequently repressed in several basal liverworts, lycopods, equisetopsids and ferns. This last hypothesis, which is supported by recent studies of transcriptional regulation of the biosynthesis of lignins, implies that lignification originated as a developmental enabler in the peripheral tissues of protracheophytes and would only later have been co-opted for the strengthening of tracheids in eutracheophytes.

Resistance in pepper plants induced by Fusarium oxysporum f. sp. lycopersici involves different defence-related genes

Inoculation with Fusarium oxysporum f. sp. lycopersici (FOL) protects pepper plants from subsequent infection with Phytophthora capsici. In the present paper, the level of local and systemic protection achieved by plants induced with FOL was evaluated by quantifying the pathogen biomass and using real-time PCR. Differences in the amount of pathogen were found in stems and roots between FOL-treated and untreated plants, while pathogen biomass could not be detected in leaves of induced plants. Five defence-related genes coding for a PR-1 protein, a beta-1,3-glucanase, a chitinase, a peroxidase and a sesquiterpene cyclase were up-regulated 48 h after treatment in all the tissues studied, and maximal mRNAs levels were found in leaves.

Diversity of Phytophthora capsici in Northwest Spain: Analysis of Virulence, Metalaxyl Response, and Molecular Characterization

Phytophthora crown rot, caused by Phytophthora capsici, is potentially the most destructive disease of pepper in Spain. Phenotypic and genetic diversity of 16 P. capsici isolates collected from 11 farms in northwest Spain was characterized based on virulence, mating type, sensitivity to metalaxyl, and genetic analysis using random amplified polymorphic DNA (RAPD) methods. Low variability was observed among the isolates in their metalaxyl response, with 87.5% being highly sensitive. No isolates of the A2 mating type were detected. More variability was found in the virulence assay, and isolates were classified into two groups according to their pathogenicity on a set of four pepper cultivar differentials. Genetic variation examined with eight RAPD primers generated 92 polymorphic bands and revealed the existence of different patterns among isolates. Cluster analysis using the unweighted pair-group method with arithmetic averages (UPGMA) separated the Spanish isolates into three RAPD groups and established a relationship between the Spanish population and a representative worldwide group of isolates. No correlation was found between groups obtained by RAPD analysis and groups defined by virulence or metalaxyl response.

Cellulase Activity in Isolates of Verticillium dahliae Differing in Aggressiveness

Ten Verticillium dahliae isolates from different Galician locations were classified by degree of aggressiveness. High variability exists independent of locality of origin. Two isolates differing in aggressiveness were evaluated for cellulase production on several carbon sources. V. dahliae is able to degrade crystalline cellulose (Avicel) and, therefore, has the three enzymes necessary for its hydrolysis. The two isolates behaved similarly in the presence of soluble cellulose, but the most aggressive isolate had greater β-1,4-glucosidase (EC. 3.2.1.21) and endo-β-1,4-glucanase (EC. 3.2.1.4) activity. The less aggressive isolate needed more time to degrade crystalline cellulose. Cellulases may not be the determining factor for aggressiveness and symptom expression; however, they may play a role in penetration.

Real-Time Polymerase Chain Reaction Quantification of Phytophthora capsici in Different Pepper Genotypes

ABSTRACT Reliable and sensitive quantification of Phytophthora capsici in pepper plants is of crucial importance in managing the multiple syndromes caused by this pathogen. A real-time polymerase chain reaction (PCR) assay was developed for the determination of P. capsici in pepper tissues. DNA levels of a highly virulent and a less virulent isolate were measured in different pepper genotypes with varying degrees of resistance. Using SYBR Green and specific primers for P. capsici, the minimal amount of pathogen DNA quantified was 10 pg. Pathogen DNA was recorded as early as 8 h postinoculation. Thereafter, the increase was rapid in susceptible cultivars and slower in resistant ones. The amount of pathogen DNA quantified in each pepper genotype correlated with susceptibility to Phytophthora root rot. Likewise, there was a relationship between the virulence of the pathogen and the degree of colonization. Differences also were found in oomycete amount among pepper tissues, with maximal pathogen biomass occurring in stems. The real-time PCR technique developed in this study was sensitive and robust enough to assess both pathogen development and resistance to Phytophthora root rot in different pepper genotypes.

O-4-Linked coniferyl and sinapyl aldehydes in lignifying cell walls are the main targets of the Wiesner (phloroglucinol-HCl) reaction

The nature and specificity of the Wiesner test (phloroglucinol-HCl reagent) for the aromatic aldehyde fraction contained in lignins is studied. Phloroglucinol reacted in ethanol-hydrochloric acid with coniferyl aldehyde, sinapyl aldehyde, vanillin, and syringaldehyde to yield either pink pigments (in the case of hydroxycinnamyl aldehydes) or red-brown pigments (in the case of hydroxybenzaldehydes). However, coniferyl alcohol, sinapyl alcohol, and highly condensed dehydrogenation polymers derived from these cinnamyl alcohols and aldehydes did not react with phloroglucinol in ethanol-hydrochloric acid. The differences in the reactivity of phloroglucinol with hydroxycinnamyl aldehydes and their dehydrogenation polymers may be explained by the fact that, in the latter, the unsubstituted (alpha,beta-unsaturated) cinnamaldehyde functional group, which is responsible for the dye reaction, is lost due to lateral chain cross-linking reactions involving the beta carbon. Fourier transform infrared spectroscopy and thioacidolysis analyses of phloroglucinol-positive lignifying plant cell walls belonging to the plant species Zinnia elegans L., Capsicum annuumvar. annuum, Populus albaL., and Pinus halepensisL. demonstrated the presence of 4- O-linked hydroxycinnamyl aldehyde end groups and 4- O-linked 4-hydroxy-3-methoxy-benzaldehyde (vanillin) end groups in lignins. However, given the relatively low abundance of 4- O-linked vanillin in lignifying cell walls and the low extinction coefficient of its red-brown phloroglucinol adduct, it is unlikely that vanillin contributes to a great extent to the phloroglucinol-positive stain reaction. These results suggest that the phloroglucinol-HCl pink stain of lignifying xylem cell walls actually reveals the 4- O-linked hydroxycinnamyl aldehyde structures contained in lignins. Histochemical studies showed that these aldehyde structures are assembled, as in the case of coniferyl aldehyde, during the early stages of xylem cell wall lignification.

O-4-Linked coniferyl and sinapyl aldehydes in lignifying cell walls are the main targets of the Wiesner (phloroglucinol-HCl) reaction

The nature and specificity of the Wiesner test (phloroglucinol-HCl reagent) for the aromatic aldehyde fraction contained in lignins is studied. Phloroglucinol reacted in ethanol-hydrochloric acid with coniferyl aldehyde, sinapyl aldehyde, vanillin, and syringaldehyde to yield either pink pigments (in the case of hydroxycinnamyl aldehydes) or red-brown pigments (in the case of hydroxybenzaldehydes). However, coniferyl alcohol, sinapyl alcohol, and highly condensed dehydrogenation polymers derived from these cinnamyl alcohols and aldehydes did not react with phloroglucinol in ethanol-hydrochloric acid. The differences in the reactivity of phloroglucinol with hydroxycinnamyl aldehydes and their dehydrogenation polymers may be explained by the fact that, in the latter, the unsubstituted (alpha,beta-unsaturated) cinnamaldehyde functional group, which is responsible for the dye reaction, is lost due to lateral chain cross-linking reactions involving the beta carbon. Fourier transform infrared spectroscopy and thioacidolysis analyses of phloroglucinol-positive lignifying plant cell walls belonging to the plant species Zinnia elegans L., Capsicum annuumvar. annuum, Populus albaL., and Pinus halepensisL. demonstrated the presence of 4- O-linked hydroxycinnamyl aldehyde end groups and 4- O-linked 4-hydroxy-3-methoxy-benzaldehyde (vanillin) end groups in lignins. However, given the relatively low abundance of 4- O-linked vanillin in lignifying cell walls and the low extinction coefficient of its red-brown phloroglucinol adduct, it is unlikely that vanillin contributes to a great extent to the phloroglucinol-positive stain reaction. These results suggest that the phloroglucinol-HCl pink stain of lignifying xylem cell walls actually reveals the 4- O-linked hydroxycinnamyl aldehyde structures contained in lignins. Histochemical studies showed that these aldehyde structures are assembled, as in the case of coniferyl aldehyde, during the early stages of xylem cell wall lignification.

Determination of dialkyldimethylammonium surfactants in sewage based on the formation of premicellar aggregates

A method is described for the determination of dialkyldimethylammonium surfactants (DDAS) in sewage, based on the formation of premicellar aggregates with sodium dodecyl sulfate and using the dye Coomassie Brilliant Blue G (CBBG) as a photometric probe. The mixed aggregates are selectively obtained at DDAS concentrations three orders of magnitude below the critical micelle concentration. As a result, DDAS can be determined at the microg l(-1) level without interference from other quaternary ammonium/pyridinium or anionic/non-ionic surfactants. Because of the selectivity of the method, the clean-up of sewage influents and effluents only involves extraction with chloroform, after formation of the DDAS-sodium dodecane sulfonic acid ion pair, evaporation of the extracts to dryness and dissolution of DDAS in 4 M hydrochloric acid. The recovery of DDAS ranged from 82 to 93% and from 100 to 105% in sewage influents and effluents, respectively.

Simultaneous retrievals of temperature and volume mixing ratio constituents from nonoxygen odin submillimeter radiometer bands

We present the retrieval of temperature and O(3) volume mixing ratio profiles in the middle atmosphere from a single strong O(3) line. We performed the study using simulated limb-sounding measurements in the frame of the submillimeter radiometer (SMR) instrument that will be carried by the Odin satellite that is due to be launched in early 2001. This study is interesting for the Odin SMR data analysis because we first provide additional temperature measurements, and second reduce significantly the O(3) retrieval error that is due to the temperature and pressure uncertainties. Nonlinear retrievals are performed to retrieve the O(3), CO, H(2)O, and temperature profiles simultaneously from the spectral band 576.27-576.67 GHz. The pressure profile is deduced from the hydrostatic equilibrium equation after each iteration. Temperature and O(3) can be retrieved throughout the stratosphere from 15-50 and 20-50 km, respectively, with a vertical resolution of 3 km. The altitude domain corresponds to the parts of the atmosphere where the signal intensity saturates in some spectrometer channels. A total error of 4-6 K has been found in the temperature profile, mainly because of the instrumental thermal noise and to a lesser extent the calibration. The total error in the O(3) profile is 5-10% and is dominated by the O(3) line-broadening parameter. The total error on the retrieved pressure profile is 2-10% because of the errors in calibration and reference pressure.

Fruit development in Capsicum annuum: changes in capsaicin, lignin, free phenolics, and peroxidase patterns

Pepper fruits, of Capsicum annuum cv. Padron, undergo changes in content of capsaicinoids, lignin, and free phenolics during the maturation process. Although capsaicinoids increase with development, the maximal levels of free phenolics and lignin are observed during the early stages of development. A decrease of peroxidase activity was observed during maturation, and this was related with a decrease in other physiological parameters studied, namely chlorophylls and pH. Subcellular fractionation studies reveal that most peroxidase activity is localized in the soluble fraction throughout development. The changes in the peroxidase activity were accompanied by changes in the different isoenzymes. Acidic isoenzymes increased whereas the basic isoenzymes decreased over the same period, and the changes in these isoenzymes were related with capsaicin metabolism.

Alterations in erythrocyte membrane lipid and fatty acid composition in Chediak-Higashi syndrome

Chediak-Higashi syndrome (CHS) is an autosomal recessive disease characterized by the presence of abnormally large cytoplasmic organelles in all body granule producing cells. The molecular mechanism for this disease is still unknown. Functional disorders in membrane-related processes have been reported. Erythrocyte membranes from four CHS patients and 15 relatives including obligatory heterozygous were studied to examine potential alterations in the lipid and fatty acid profile of erythrocyte membranes associated with this syndrome. Plasma concentrations of cholesterol, triglycerides, phospholipids, and apolipoproteins AI and B100, and the lipid components of very low-, intermediate-, low- and high-density lipoproteins were also determined. CHS erythrocyte membranes were found to be enriched with lipids in relation to protein and to show: (1) an increase in cholesterol and choline-containing phospholipids (sphingomyelin and phosphatidylcholine) that predominate in the outer monolayer, which is higher than the increase in phosphatidylserine and phosphatidylethanolamine, that are chiefly limited to the inner monolayer in normal red blood cells; (2) a relative palmitic acid and saturated fatty acid increase and arachidonic acid and unsaturated fatty acid decrease, this resulting in a lower unsaturation index than controls. Changes in CHS erythrocyte membrane lipids seem to be unrelated to serum lipid disorders as plasma lipid and apolipoprotein concentrations were apparently in the normal range, with the exception of a modest hypertriglyceridemia in patients and relatives and a decreased concentration of HDL cholesterol in patients. These findings indicate that CHS erythrocyte membranes contain an abnormal lipid matrix with which membrane proteins are defectively associated. The anomalous CHS membrane composition can be explained on the postulated effects of the CHS1/Lyst gene.

The importance of a tumor capsule in columnar cell thyroid carcinoma: a report of two cases and review of the literature

Two cases of papillary columnar cell thyroid carcinoma are presented. A 49-year-old man presented with lymph node and pulmonary metastases at diagnosis; a 51-year-old woman developed local recurrence and lung and bone metastases 3 years postsurgery. Death occurred after 52 and 57 months, respectively. The first case lacked a tumor capsule, although the second exhibited capsule remains with extensive tumor cell infiltration. A review is made of all similar cases reported to date in the literature, placing emphasis on the epidemiological and prognostic differences observed in terms of circumscribed or noncircumscribed tumor. The presence of a capsule was associated with a higher frequency of female patients and a favorable prognosis. In contrast, tumors profusely infiltrating the thyroid parenchyma or extrathyroid tissues in the absence of a capsule, found in similar proportion of men and women had a fatal prognosis.

T cell receptor V-segment frequencies in peripheral CD8+ T cells in aging

Infections are a major cause of illness and death amongst elderly people. Peripheral blood CD8+ T lymphocytes --which play a crucial role in host defence against viral infections--, are divided in subsets based upon the expression of several cell and activation markers. In senescence changes and variations in peripheral CD8+ T lymphocyte compartment have been described, and such a decrease in the CD8+CD45RA+ lymphocytes. In this report the T V alpha and Vbeta cell specificities repertoire usage in aging subjects were studied by the use of seven different monoclonal antibodies specific for defined regions of the TCR. Except for the Vbeta6subfamily, no differences between old and control subjects in frequency of T cells bearing selected V alphabeta epitopes, were observed.

Neutrophil function in elderly persons assessed by flow cytometry

It is well known that the immune response declines with senescence and it is suggested that these changes render an individual susceptible to infection, autoimmune phenomena and cancer. Bacterial and viral infections are a major cause of illness and death amongst aged subjects, and once infection is established, the elderly also have a diminished capacity to prevent its spread (1). The cellular and molecular basis for this age-related decline in immunocompetence are still unknown and, possibly, are related to an alteration in cell transduction mechanisms (2).

T cell receptor V-segment frequencies in aged individuals

The T V alpha and V beta cell specificities repertoire usage in aging subjects was studied by the use of seven different monoclonal antibodies specific for defined regions of the T cell receptor (TCR). Except for the V beta 8 subfamily, no differences were observed in the frequency of T cells bearing selected V alpha beta epitopes, between old and control subjects.

CD8+ T cell subsets in aging

Infections are major cause of illness and death amongst elderly people. Peripheral blood CD8+ T lymphocytes -which play a crucial role in host defence against viral infections-. are divided in subsets based upon the expression of several cell and activation markers. Since in senescence changes in peripheral blood CD8+ T lymphocyte compartment have been described, studies were performed to determine whether in aging there are variations in the peripheral blood CD8+CD38+, CD8+CD57+, CD8+HLA-DR+, CD8+CD45RA+ and CD8+CD45RO+ cell subset. A decrease in the CD8+CD45RA+ lymphocytes was observed, indicating that variations in the CD8+ compartment can take place with ageing.

Pneumococcal aortitis in the antibiotic era

The pneumococcus remains in the antibiotic era a formidable pathogen, capable of atypical, lethal clinical presentations. We report two fatal cases of thoracic aortitis caused by Streptococcus pneumoniae in the setting of bacteremic illness from this pathogen. One case occurred in an aortic graft and the other arose in a native aorta. We also discuss the indolent clinical presentation and the diagnostic failure of transesophageal echocardiography and leukocyte scintigraphy. Persistent pyrexia with atypical chest pain and unexplained blood loss should alert clinicians to the possibility of this uncommon, yet lethal complication of pneumococcal disease.

Na,K-ATPase activity in red blood cells from patients with Chediak-Higashi syndrome

Na,K-ATPase activity of red blood cells from Chediak-Higashi syndrome (CHS) patients and relatives (gene heterozygous) was determined and compared to that of control, healthy, individuals. The enzyme activity was found to be strongly diminished in the CHS patients and slightly lower in their relatives. This reduced activity was due to a lower turnover number of the Na, K-ATPase as well as a decreased number of pumps. The reduced enzyme activity observed in these patients could be the result of an abnormal cell membrane fluidity, and the lowered number of Na, K-pumps could be explained as a consequence of an altered or deficient cell machinery caused by the CHS gene.

Distribution of the HLA-DQA1 polymorphism in the population of the Basque Country (Spain)

Allele and genotype frequencies at the HLA-DQA1 locus were determined in Basque Country populations using PCR methodology and a dot-blot assay with ASO probes. The results showed no deviation from the Hardy-Weinberg equilibrium. No differences were found between the three Basque Provinces, but gene frequencies were significantly different from those of some other Spanish and world populations.

HTLV-I/II infections in Spain. The HTLV-I/II Spanish Study Group

Antibodies to HTLV-I/II were investigated in sera from 7521 individuals living in Spain. They were classified in four major groups: a) subjects at high risk of retroviral infections e.g. parenteral drug addicts, homosexuals, prostitutes, and multiple-transfused individuals; b) patients suffering illness associated with HTLV-I in endemic regions; c) immigrants from endemic areas; and d) blood donors. Sera were collected from 1984 to December 1991. Repeatedly reactive ELISA was found in 211 samples (2.8%), but Western blot only confirmed the presence of HTLV-I/II antibodies in 23 samples (0.30%), corresponding to eight (0.25%) out of 3207 drug abusers, six (0.72%) out of 894 immigrants (five Africans and one South American), three (0.41%) out of 727 patients with HTLV-related diseases (one woman with HTLV-I associated myelopathy had received blood transfusions in an endemic area), four (0.54%) out of 793 prostitutes, one multiple-transfused native woman, and one (0.16%) out of 603 native seamen. The Western blot antibody pattern confirmed HTLV-II infection instead of HTLV-I in nine (39%) subjects. The remaining 14 (61%) HTLV-reactive samples were interpreted as HTLV-I seropositive, most of which were from immigrants. None of 857 blood donors analysed was reactive for HTLV antibody. These results suggest that both HTLV-I and HTLV-II are present in Spain, although at a low rate and mostly restricted to individuals coming from endemic areas, drug addicts, and prostitutes. Furthermore, diseases related to HTLV-I (particularly lymphoproliferative disorders, and subacute myelopathies) seem to be rarely associated with these viruses in Spain, a non-endemic area.

[Multicenter study of HTLV-I and HTLV-II infection in Spain. Spanish Group for the Study of HTLV-II/II Infection]

BACKGROUND

Human T-lymphotropic viruses type I (HTLV-I) and type II (HTLV-II) infections have been related to lymphoproliferative disorders and subacute neurological diseases. Screening blood donors for specific HTLV-I/II antibody has been implemented in Japan, United States, and recently in France. Should be it recommended in Spain?

METHODS

Antibodies to HTLV-I/II were investigated in sera from 7,884 individuals living in Spain. They were classified in four major groups: 1) subjects at high-risk for retrovirus infection, as drug addicts, homosexuals, and polytransfused individuals (n = 4,740), 2) patients suffering HTLV-like symptoms (n = 760), 3) immigrants from or travellers to endemic areas (n = 1,427), and 4) blood donors (n = 957).

RESULTS

Eighteen (0.22%) subjects were HTLV-I positive and 11 (0.12%) were classified as HTLV-II reactive. Five (71.5%) of 7 immigrants or travelers to endemic areas reacting against HTLV were typed as HTLV-I. Six (60%) of 10 drug addicts HTLV-reactive were typed as HTLV-II carriers.

CONCLUSIONS

Both HTLV-I and HTLV-II infections are present in Spain, although in a low rate and mostly restricted to drug addicts (HTLV-II), and people coming from endemic regions (HTLV-I). All tested blood donors were negative. In this view, HTLV-I/II screening in Spanish blood banks seems to be non urgent, although alternative strategies should be considered.

[Human immunodeficiency virus infection in the Spanish population. Review of the literature]

The epidemiological aspects of the infection by the human immunodeficiency virus, HIV, in the Spanish population as described in the literature are reviewed. From the published studies is evident that HIV infection is limited to the population risk groups established in the epidemiological world reports, heroin addicts, homosexuals, heterosexuals with sexual contacts with infected persons and blood and hemoderivates receptors. The observed frequencies in these risk groups are similar to that described in other countries.

Regulation of natural killer cytotoxicity by 1,25-dihydroxyvitamin D3

The steroid hormone 1 alpha, 25-dihydroxyvitamin D3, calcitriol, is crucial in calcium homeostasis. Calcium plays a central role in T, B, and NK cell functions, and calcitriol is a known inhibitor of T cell proliferation and immunoglobulin production. We have analyzed here the immunoregulatory effects of calcitriol on NK cell function. We show that calcitriol specifically specifically inhibits, in a time- and dose-dependent fashion, the generation of cytotoxic activity from cultured CD16+ peripheral blood NK cells. It also suppresses, at similar molar concentrations (1-10 nM), interleukin 2 (IL-2) production by PHA-activated peripheral blood lymphocytes. Calcitriol does not interfere with the cytotoxic function of NK cells, whether fresh or generated in vitro, placing the inhibition at the level of NK cell activation. Interestingly enough, exogenous IL-2 can completely reverse the suppressive effect. These findings suggest that modulation of NK cell activation by control of the internal level of IL-2 may reflect an additional paracrine calcitriol-dependent circuit with immunoregulatory consequences.

Decreased TcR-CD3+ T cell numbers in healthy aged humans. Evidence that T cell defects are masked by a reciprocal increase of TcR-CD3- CD2+ natural killer cells

While there is accumulating evidence to indicate the presence of functional abnormalities in T cells from aged healthy humans, their cellular basis remains unclear. By using two-color immunofluorescence and multiparameter flow cytometry we show that (a) the number of peripheral blood antigen receptor-positive (TcR-CD3+) T cells is significantly lower in aged than in young adults; (b) the numbers of E-rosette-forming (CD2+) cells are maintained in the elderly due to a reciprocal increase in the frequency of TcR-CD3- cells, which constitute only a minor lymphocyte subpopulation in young adults, and (c) TcR-CD3-CD2+5- lymphocytes exhibit the phenotypic features of natural killer (NK) cells. By using functional assays we show the TcR-CD3-CD2+16+ lymphocytes are indeed NK cells because they are activated by and lyse NK targets. In contrast, they are unresponsive to either phytohemagglutinin or mitogenic CD2 monoclonal antibody stimulation, which in turn activates TcR-CD3+CD2+16- T cells. We conclude that the increase in TcR-CD3-CD2+ NK cells masks the T cell reduction in aged humans by normalizing CD2+ cell frequencies. However, NK cells cannot functionally substitute the thymus-derived lymphocytes they replace.

Interleukin-2 induces cytotoxic activity in lymphocytes from regional axillary nodes of breast cancer patients

Natural killer (NK) cells and lymphokine-activated killer (LAK) cells have been involved in immunosurveillance against tumors. A normal NK activity was observed in peripheral blood (PB) mononuclear cells (MNC) from women with breast cancer, but a very low or absent NK cytotoxicity was found in the regional lymph node (RLN) MNC. However, strong cytotoxic activity against NK-resistant and NK-sensitive target cells can be induced in RLN MNC by long-term (5-day) incubation with recombinant interleukin-2 (rIL-2). This cytotoxic inducer effect of rIL-2, not observed with recombinant interferon gamma, was dose and time-dependent and was not associated with modifications in the low number of Leu 11+ or Leu 7+ cells present in the population. Both the lack of NK activity and the generation of rIL-2-activated killer cells can be readily demonstrated in either histologically affected or unaffected RLN. These results stress the value of the immunomodulators inducing cytotoxic activity in RLN MNC of patients with tumors, and are discussed in association with their possible therapeutical role.