Investigating the role of nicotinic acetylcholine receptors in menthol's effects in mice

The use of menthol in tobacco products has been linked to an increased likelihood of developing nicotine dependence. The widespread use of menthol can be attributed to its unique sensory characteristics; however, emerging evidence suggests that menthol also alters sensitivity to nicotine through modulation of nicotinic acetylcholine receptors (nAChRs). Nicotinic subunits, such as β2 and α5, are of interest due to their implications in nicotine reward, reinforcement, intake regulation, and aversion. This study, therefore, examined the in vivo relevance of β2 and α5 nicotinic subunits on the pharmacological and behavioral effects of menthol. Data suggests that the α5 nicotinic subunit modulates menthol intake in mice. Overall, deletion or a reduction in function of the α5 subunit lessened aversion to menthol. α5 KO mice and mice possessing the humanized α5 SNP, a variant that confers a nicotine dependence phenotype in humans, demonstrated increased menthol intake compared to their WT counterparts and in a sex-related fashion for α5 SNP mice. We further reported that the modulatory effects of the α5 subunit do not extend to other aversive tastants like quinine, suggesting that deficits in α5* nAChR signaling may not abolish general sensitivity to the aversive effects of other noxious chemicals. Further probing into the role of α5 in other pharmacological properties of menthol revealed that the α5 subunit does not modulate the antinociceptive properties of menthol in mice and suggests that the in vivo differences observed are likely not due to the direct effects of menthol on α5-containing nAChRs in vitro.

Genetic Modifiers of Oral Nicotine Consumption in Chrna5 Null Mutant Mice

The gene CHRNA5 is strongly associated with the level of nicotine consumption in humans and manipulation of the expression or function of Chrna5 similarly alters nicotine consumption in rodents. In both humans and rodents, reduced or complete loss of function of Chrna5 leads to increased nicotine consumption. However, the mechanism through which decreased function of Chrna5 increases nicotine intake is not well-understood. Toward a better understanding of how loss of function of Chrna5 increases nicotine consumption, we have initiated efforts to identify genetic modifiers of Chrna5 deletion-dependent oral nicotine consumption in mice. For this, we introgressed the Chrna5 knockout (KO) mutation onto a panel of C57BL/6J-Chr#A/J/NAJ chromosome substitution strains (CSS) and measured oral nicotine consumption in 18 CSS and C57BL/6 (B6) mice homozygous for the Chrna5 KO allele as well as their Chrna5 wild type littermates. As expected, nicotine consumption was significantly increased in Chrna5 KO mice relative to Chrna5 wildtype mice on a B6 background. Among the CSS homozygous for the Chrna5 KO allele, several exhibited altered nicotine consumption relative to B6 Chrna5 KO mice. Sex-independent modifiers were detected in CSS possessing A/J chromosomes 5 and 11 and a male-specific modifier was found on chromosome 15. In all cases nicotine consumption was reduced in the CSS Chrna5 KO mice relative to B6 Chrna5 KO mice and consumption in the CSS KO mice was indistinguishable from their wild type littermates. Nicotine consumption was also reduced in both Chrna5 KO and wildtype CSS mice possessing A/J chromosome 1 and increased in both KO and wild type chromosome 17 CSS relative to KO and wild type B6 mice. These results demonstrate the presence of several genetic modifiers of nicotine consumption in Chrna5 KO mice as well as identify loci that may affect nicotine consumption independent of Chrna5 genotype. Identification of the genes that underlie the altered nicotine consumption may provide novel insight into the mechanism through which Chrna5 deletion increases nicotine consumption and, more generally, a better appreciation of the neurobiology of nicotine intake.

The effects of oral nicotine administration and abstinence on sleep in male C57BL/6J mice

BACKGROUND

Sleep disturbances are common in smoking cessation attempts and are predictive of relapse. Despite this knowledge, there is no established animal model to study the effect of nicotine abstinence on sleep and EEG parameters.

OBJECTIVES

The present study was conducted to characterize sleep and wakefulness in male C57BL/6J mice during periods of oral nicotine administration and abstinence.

METHODS

Male C57BL/6J mice were implanted with EEG/EMG recording devices. EEG/EMG data were recorded continuously for a period of 4 weeks. At the beginning of week 2, 200 μg/ml of nicotine was added to the 0.2% saccharin vehicle drinking solution. Following a 2-week period of oral nicotine administration, abstinence was initiated by excluding the nicotine from the 0.2% saccharin vehicle drinking solution. EEG/EMG were analyzed at pre-nicotine baseline, during nicotine administration, and on days 1, 2, and 5 of abstinence from nicotine.

RESULTS

Oral nicotine administration decreased total sleep time during the active phase, consistent with the stimulant actions of nicotine. In contrast, NREM sleep quantity was increased during the active phase on nicotine abstinence day 1 and REM sleep was decreased during days 2 and 5 of abstinence. Further, sleep fragmentation was increased during the inactive phase on all days of abstinence. Oral nicotine administration and abstinence from nicotine also altered EEG relative power frequencies during the inactive and active phase.

CONCLUSIONS

Both oral nicotine administration and abstinence lead to sleep disturbances in mice. Similarities between this model and human reports on the effect of nicotine/nicotine withdrawal on sleep support its utility in examining the molecular mechanisms that modulate the relationship between sleep, nicotine, and nicotine abstinence/withdrawal.

Aberrant nuclear expression of AP-1 and NFkappaB in lymphocytes of women stressed by the experience of breast biopsy

We have investigated the expression of AP-1 and NFkappaB in peripheral blood lymphocytes of women scheduled for breast biopsy. Samples were collected when women were informed of the need for biopsy (prebiopsy, T1, 5-7 days prior to the actual biopsy) and 7-10 days after they learned the result of their biopsy (postbiopsy, T2). At the time of blood collection, psychological stress was evaluated using Speilberger's State Trait Anxiety Inventory (STAI) and the Profile of Mood States (POMS). Women scheduled to undergo breast biopsy reported significant increases in anxiety (STAI) and mood disturbance (POMS). Gel shift mobility assays showed that mitogen stimulated peripheral blood lymphocytes of these women were less capable of the nuclear expression of AP-1 or NFkappaB at T1. Similar assessments, 7-10 days after the women learned of the results of their breast biopsy, showed these same women to have a marked reduction in anxiety and mood disturbance and an increased nuclear translocation of AP-1 and NFkappaB. These results show a significant decrease in nuclear AP-1 and NFkappaB expression during the period of emotional distress prior to biopsy with a return of nuclear transcription activity to normal levels when distress was relieved. Several studies have correlated increased psychological stress with decreased immune function. The results of this study suggest that psychological stress may mediate immunosuppression by altering the expression of the transcription factors, AP-1 and NFkappaB.

Human thymic epithelial cells inhibit IL-15- and IL-2-driven differentiation of NK cells from the early human thymic progenitors

T/NK progenitors are present in the thymus; however, the thymus predominantly promotes T cell development. In this study, we demonstrated that human thymic epithelial cells (TEC) inhibit NK cell development. Most ex vivo human thymocytes express CD1a, indicating that thymic progenitors are predominantly committed to the T cell lineage. In contrast, the CD1a(-)CD3(-)CD56(+) NK population comprises only 0.2% (n = 7) of thymocytes. However, we observed increases in the percentage (20- to 25-fold) and absolute number (13- to 71-fold) of NK cells when thymocytes were cultured with mixtures of either IL-2, IL-7, and stem cell factor or IL-15, IL-7, and stem cell factor. TEC, when present in the cultures, inhibited the increases in the percentage (3- to 10-fold) and absolute number (3- to 25-fold) of NK cells. Furthermore, we show that TEC-derived soluble factors inhibit generation of NK-CFU and inhibit IL15- or IL2-driven NK cell differentiation from thymic CD34(+) triple-negative thymocytes. The inhibitory activity was found to be associated with a 8,000- to 30,000 Da fraction. Thus, our data demonstrate that TEC inhibit NK cell development from T/NK CD34(+) triple negative progenitors via soluble factor(s), suggesting that the human thymic microenvironment not only actively promotes T cell maturation but also controls the development of non-T lineage cells such as the NK lineage.

Reduced levels of Hsp70 result in a therapeutic effect of 15-deoxyspergualin on acute graft-versus-host disease in (DA x LEW)F1 rats

We have shown previously that increased levels of hsp70, and antibodies reactive with hsp70 parallel the onset and severity of graft-versus-host disease (GVHD) in a parent --> (DA x LEW)F1 rat model. In this study we have assessed the effect of reducing the levels of the 70 kDa heat shock protein (hsp70), on the morbidity and mortality of acute GVHD in (DA x LEW)F1 rats. The reduction was accomplished by the administration of 15-deoxyspergualin (DSG), an immunosuppressive agent which binds to a constitutively expressed member of the 70 kDa heat shock protein family. DSG administered via three different protocols reduced GVHD-associated morbidity. One of the regimens, which consisted of intermittent DSG administration, also significantly reduced GVHD associated mortality. This DSG treatment reduced hsp70 levels in spleen and lymph nodes, inhibited anti-hsp70 antibody production, and diminished the serum levels of IL-2, IFN-gamma, TNF-alpha, and IL-10. IL-4 levels in the serum did not change during GVHD and were not effected by DSG. These results show that the mechanism of DSG immunosuppressive effect in rat GVHD may involve DSG's capacity to bind to hsp70, which in turn may lead to a decrease in levels of circulating anti-hsp70 antibodies, and reduced production of cytokines.

Reduced capacity of neonatal lymphocytes to inhibit the growth of Candida albicans

Opportunistic microorganisms produce significant morbidity and mortality in preterm and term infants. Because of the heightened susceptibility of infants to opportunistic fungal infections, neonatal lymphocytes were assessed for their capacity to inhibit the growth of Candida albicans. Lymphocytes from both preterm and term cord blood demonstrated significantly less effect upon C. albicans than did lymphocytes from adults. Neonatal lymphocytes of infants <32 weeks of gestation showed a marked reduction in growth inhibitory capacity compared to infants >32 weeks of gestation. Lymphocytes from female infants had a significantly greater fungal growth inhibitory capacity than did lymphocytes from male infants. These results show that neonatal lymphocytes have a reduced capacity to inhibit the growth of C. albicans. This reduced antifungal capacity may underlie the increased susceptibility of such infants to opportunistic microorganisms, like C. albicans.

Stress reduction and HIV disease: a review of intervention studies using a psychoneuroimmunology framework

The field of psychoneuroimmunology (PNI) posits that relationships exist between stress, immunological impairment, and health outcomes. Accumulating evidence suggests that stress may hasten HIV disease progression by increasing viral replication, suppressing immune response, and inducing deleterious health-related behaviors. Interventions that attenuate the effects of stress are postulated to operate by altering cognitive perception and/or modulating neuroendocrine and sympathetic reactivity. A review of HIV/PNI intervention studies is presented as a guide for the inclusion of stress reduction interventions in comprehensive plans of care for HIV-infected individuals. Although effect and sample sizes are small, the results of these studies provide support for a positive effect of various interventions on immunological and health-related indices in HIV-infected individuals.

Differential effects of glucocorticoids on colony stimulating factors produced by neonatal mononuclear cells

The purpose of this study was to examine the effect of dexamethasone (DEX) on the production of granulocyte and granulocyte-macrophage colony stimulating factors (G-CSF and GM-CSF) by neonatal mononuclear cells. Mononuclear cells were isolated from umbilical cord blood and cultured with either phorbol myristate acetate/phytohemagglutinin (PMA/PHA) or Candida albicans with or without DEX (10(-8)-10(-6) M) for 48 h. Cell supernatants were assayed for G-CSF and GM-CSF by ELISA. Mononuclear cells from term and preterm infants responded to PMA/PHA stimulation with a significant increase in G-CSF production over baseline levels. The PMA/PHA-induced increase in G-CSF production was markedly augmented by the addition of DEX to cell cultures. DEX augmented production of G-CSF was significantly less in mononuclear cells from preterm infants. Similarly, production of G-CSF was significantly less by mononuclear cells from infants with acute physiology scores of > or = 10, as judged by the Score for Acute Neonatal Physiology. In contrast, DEX significantly inhibited PMA/PHA-induced GM-CSF production. Although C. albicans induced mononuclear cells to produce G-CSF, DEX did not significantly augment this production. No significant effect of DEX on C. albicans induced GM-CSF production was observed. The data show DEX induced differential regulation of infant peripheral blood mononuclear cell production of G-CSF and GM-CSF. These results suggest that glucocorticoids may enhance certain aspects of host immune function in addition to their well-documented immunosuppressive effects. Further, the neutrophilia observed in DEX-treated infants may be due to enhanced G-CSF production.

Stress and HIV disease progression: psychoneuroimmunological framework

Psychoneuroimmunology (PNI) is the study of the interrelationships among behavior, neural and endocrine function, and the immune system. PNI investigates the relationships among stress, physiological dysregulation, and health outcomes. Research has supported the theory that emotional distress and the resultant neuroendocrine activation can induce immune system suppression. This suppression has significant implications for disease susceptibility and progression. HIV disease and its extensive immunological consequences are explored within this framework. Potential physiological pathways that may mediate stress-induced dysregulation within the context of HIV disease are identified. Key HIV-related PNI research studies are reviewed and critically analyzed. Implications for nursing practice and research are discussed.

Effect of d-fenfluramine on the lymphocyte response of HIV+ humans

The objective of this study was to analyse the effect of d-dexfenfluramine (d-FEN) on the human lymphocyte response, in vitro. Experiments were designed to determine whether d-FEN augments specific human immune parameters associated with protection from opportunistic microbial pathogens and particularly focuses on d-FEN as a means by which to augment the function of CD8+ and CD4+ lymphocytes. Lymphocytes were examined for three reasons: (1) for their ability to inhibit the growth of Candida albicans; (2) for their ability to proliferate in response to a mitogen; and, (3) their cytokine profile (vis., production of IL-2, IFN-gamma and TNF-alpha). Peripheral blood mononuclear cells (PBMC) were obtained from 20 HIV+ patients. The patients were diagnosed as HIV+ within the past 0.5-9 years. d-FEN was found to augment the capacity of CD8+ lymphocytes to inhibit the growth of the opportunistic microbial pathogen, C. albicans. d-FEN enhanced the capacity of CD4+ lymphocytes to proliferate in response to the mitogen, Concanavalin A, and to increase the amount of IL-2 produced by CD4+ and CD8+ lymphocytes from AIDS patients. d-FEN increased the number of CD4+ and CD8+ lymphocytes that produced IFN-gamma from either non-AIDS or AIDS patients and increased the number of AIDS patient's CD8+ lymphocytes that produce TNF-alpha. These in vitro data suggest that d-FEN may be effective in enhancing immune function in immunocompromised individuals.

Antifungal activity of interleukin-2-activated natural killer (NK1.1+) lymphocytes against Candida albicans

Interleukin-2 (IL-2)-activated lymphocytes interact directly with, and inhibit, the growth of Candida albicans hyphae. C. albicans-stimulated natural killer (NK1.1+) lymphocytes were demonstrated to secrete a soluble product capable of directly affecting C. albicans yeast forms. Antibodies specific for interferon-gamma completely eliminated the antifungal activity of the NK1.1+ lymphocyte product and diminished the antifungal activity of NK1.1+ lymphocytes against C. albicans. Antibodies specific for other cytokines had no such effect. These data demonstrate that C. albicans-stimulated NK1.1+ lymphocytes have antifungal activity against C. albicans yeast cells via the release of interferon-gamma. This antifungal activity was demonstrable only against the yeast form of the fungus, with no effect on C. albicans hyphae.

Candida albicans: an opportunistic threat to critically ill low birth weight infants

Major advances in the management of critically ill low birth weight (LBW) infants have increased their survival. Yet the clinical course of these infants is complicated by the emergence of opportunistic microbial pathogens. Most importantly, serious infections from opportunistic fungi, such as Candida albicans, have produced systemic disease in vulnerable LBW infants. Invasive C. albicans infection is generally difficult to manage and is associated with high morbidity and mortality. Because the infection has an insidious and rapid course, the critical care nurse and advanced practice nurse need to provide key prevention and early treatment measures.

Effect of Pichia anomala killer toxin on Candida albicans

The effect of a Pichia anomala killer toxin upon a Candida albicans-sensitive strain was studied. Yeast and hyphae, after treatment with the toxin, were less capable of uptaking either [3H]-uridine or [35S]-methionine. In addition, the hyphal form of the fungus appeared to be less capable of DNA synthesis after toxin treatment. No effect of the killer toxin was shown upon a natural resistant mutant of the source strain. These data suggest that, similar to other killer yeast toxins, the toxin of P. anomala can produce a number of quantifiable effects upon sensitive C. albicans cells.

Trauma-induced immune dysfunction: a challenge for critical care

Multiply injured trauma patients present a major challenge for the critical care nurse. Should the patient survive the initial injuries, the third phase of mortality (five to seven days following injury) is sepsis. Research findings document a strong link between trauma and immune dysfunction. This article highlights the main immunological defects and underlying mechanisms for trauma-induced immune dysfunction. It provides the theoretical foundation that underlies the rationale for current and future immune-based therapy for trauma patients. Because of the complexity of caring for and preventing septic complications in the trauma patient, advanced practice nurses and nurse educators can use this material to update the knowledge and skills of critical care nurses.

Human immune cells mediate catecholamine secretion from adrenal chromaffin cells

OBJECTIVES

To determine the ability of human mononuclear cells to produce factors that cause catecholamine secretion from adrenomedullary chromaffin cells; to determine conditions that stimulate mononuclear cells to produce such factors; and to compare these results with catecholamine secretion in response to the cytokines interleukin (IL)-1 and IL-2.

DESIGN

Randomized, controlled, prospective study using in vitro conditions.

SETTING

University research laboratory.

SUBJECTS

Human mononuclear cells and porcine chromaffin cells.

INTERVENTIONS

Circulating human mononuclear cells were isolated and cultured overnight in RPMI media. Cell-free media from these cultures (conditioned media) were then tested for the ability to cause epinephrine secretion from porcine chromaffin cells. Mononuclear cells were stimulated with phytohemagglutinin or by mixing cells from two different individuals while suppression was tested with dexamethasone. Catecholamine secretion in response to IL-1 and IL-2 (50 and 500 units/well, respectively), or nicotinic agonist dimethylphenylpiperazinium (10 microM, which mimics the action of acetylcholine), was tested for comparison.

MEASUREMENTS AND MAIN RESULTS

Isolated porcine chromaffin cells had stable catecholamine content at the time of secretion measurements, and catecholamine release from cells into the media was measured using electrochemical detection after high-performance liquid chromatography separation. Catecholamine secretion was expressed as a percentage of the total cellular content. Epinephrine secretion due to human conditioned media was 6.9 +/- 1.0% compared with 1.4 +/- 0.6% for control media (p < .05) and 14.6 +/- 3.3% for dimethylphenylpiperazinium (p < .05). Epinephrine secretion with conditioned media from mixed cells (mixed leukocyte reaction) was 16.6 +/- 1.2%, which was higher than the epinephrine secretion caused by media from a single donor (6.9% +/- 1.0, p < .001). Pretreatment with dexamethasone inhibited the formation of bioactive products from mixed mononuclear cell preparations. Cytokines IL-1 and IL-2 did not stimulate chromaffin cell epinephrine secretion above background release with control media incubation. In all cases, norepinephrine secretion was similar to that of epinephrine, and results are included in all figures.

CONCLUSIONS

Factors released from human immune cells can mediate epinephrine and norepinephrine release from adrenomedullary cells through a nonneural mechanism. Such immune cell factor release can be modulated by immunostimulation and steroid suppression. Release of such factors in vivo may contribute to increased circulating epinephrine in response to infectious challenge and may be an important factor in the critically ill patient.

Expression of 70-kDa heat-shock protein during acute graft-versus-host disease

Acute lethal graft-versus-host disease (GVHD) was induced in unirradiated (LEW x DA)F1 rats by injection of DA parental lymphoid cells. Control rats received the same dose of (LEW x DA)F1 cells. The level of hsp70 at different stages of GVHD was examined in the spleen, lymph nodes, thymus, liver, lung, kidney, heart, and skeletal muscles of GVHD and control animals. Hsp70 was present in all organs analyzed in both groups and, with the exception of the spleen and lymph nodes, detectable levels remained constant during the disease. However, the spleen and lymph nodes of GVHD rats showed distinct changes in the hsp70 levels throughout the course of the disease. Expression of hsp70 in spleen and lymph nodes was augmented 7 and 14 days after induction of the disease. During the last stages of GVHD, 18-21 days after the induction, expression of hsp70 diminished to a level similar to that in untreated and control animals. Elevated levels of hsp70 in lymphoid organs during GVHD suggest an involvement of hsp70 in the pathology of the disease.

Induction of apoptotic cell death in a neuroblastoma cell line by dibucaine

Dibucaine, a local anesthetic known to interact with cell membranes, induced apoptosis in SK-N-MC human neuroblastoma cells in a dose-dependent manner. Apoptosis was demonstrated by direct visualization of morphological nuclear changes using a DAPI staining technique and confirmed by the production of characteristic ladder patterns of DNA fragmentation on gel electrophoresis. At concentrations which induced apoptosis, dibucaine significantly altered membrane fluidity, indicating that fluidity may be a major target for the cytotoxic action of dibucaine. Also, dibucaine increased intracellular calcium levels more effectively in calcium-containing Krebs-Ringer buffer than in calcium-free Krebs-Ringer buffer. Removal of extracellular calcium or addition of antioxidants or protein synthesis inhibitor effectively blocked dibucaine-induced apoptosis. These results suggest that membrane damage, intracellular calcium levels, and oxygen free radicals may be involved in the apoptosis induced by dibucaine.

Correlation of middle meatal and maxillary sinus cultures in acute maxillary sinusitis

Cultures obtained from the middle meatus have been used frequently in the past to direct therapy in patients with acute maxillary sinusitis. However, no convincing data have been published to indicate that middle meatal cultures accurately represent the bacterial flora within the maxillary sinus. The hypothesis of this experiment is that bacteria obtained by directed middle meatal cultures qualitatively and quantitatively correlate with cultures taken by maxillary sinus puncture. Acute sinusitis was induced by injecting 10(8) colony-forming units of bacteria directly into the maxillary sinuses of rabbits in which the ostia were occluded with cotton packs. Eight animals were injected with Staphylococcus aureus, eight with Haemophilus influenzae, and eight with Streptococcus pneumoniae. The packs were removed after 3 days, and specimens were obtained from the middle meatus in the region of the maxillary sinus ostium, and from the maxillary sinus, 1 day later. The contralateral maxillary sinuses of six of the animals were injected with normal saline and served as controls. There was a 100% correlation rate between cultures of specimens obtained from the maxillary sinus and from the middle meatus in all 24 animals. In addition, the quantitative counts from the middle meatus and the maxillary sinus correlated. Control animals showed no bacterial growth from either the middle meatus or the maxillary sinus. These results show that, in an animal model of acute sinusitis, cultures of specimens from the middle meatus reflect the contents of the maxillary sinus.

Lymphocytes utilize CD11b/CD18 for adhesion to Candida albicans

Large granular lymphocytes require adherence to hyphae of Candida albicans to inhibit growth of this fungus. This study was undertaken to identify the lymphocyte surface structures that mediate this adhesion. Monoclonal antibodies specific for epitopes of the alpha subunit (CD11b) and the beta 2 subunit (CD18) of Mac-1 eliminated lymphocyte adhesion to C. albicans hyphae. Significant inhibition of lymphocyte adhesion to C. albicans was also achieved with known protein ligands of Mac-1. These proteins included the extracellular matrix proteins vitronectin, laminin, and fibrinogen as well as two engineered peptides containing RGD (arginine-glycine-aspartic acid) sequences. Carbohydrates including N-acetyl-D-glucosamine which have been demonstrated to inhibit Mac-l-mediated adhesion to whole yeast and yeast zymosan also blocked lymphocyte adhesion to hyphae. These results identify Mac-1 (CD11b/CD18) as the surface structure that mediates lymphocyte adhesion to C. albicans. A model is proposed for lymphocyte Mac-1 activation by microbial ligands.

Mononuclear-cell peptide mediation of chromaffin-cell epinephrine secretion

Previously, we have shown that novel mononuclear-cell-derived factor(s) [molecular weight (MW) < 3,000] stimulate the release of epinephrine (EPI) from adrenal medullary chromaffin cells to levels comparable to that of maximal cholinergic stimulation. The present study provides evidence that the observed bioactivity is due to the action of a single peptide of 627 Da apparent MW. The peptide nature of the bioactive component was suggested by a decreased bioactivity after acid hydrolysis as well as altered bioactivity subsequent to peptidase (carboxypeptidase Y, leucine aminopeptidase) treatment. The bioactive conditioned-medium (CM) peptide(s) were isolated and further characterized using SDS-PAGE analysis. SDS-PAGE separation of G-25 Sephadex purified CM shows that bioactivity resides in a single peptide band. Additional studies revealed that CM also mediates norepinephrine release from sympathetic ganglia cells. Regulation of peptide production was shown to involve negative feedback in that incubation with mononuclear cells with EPI prevented further bioactive peptide release. This feedback inhibition was partially blocked by the beta-adrenergic receptor antagonist propranolol. These findings suggest a novel and potentially important mechanism by which the immune system can alter neuroendocrine function.

Effect of d-fenfluramine on the local immune response to the opportunistic microbial pathogen Candida albicans

In this study the effects of systemic administration of d-fenfluramine on the local lymphocyte response to Candida albicans was evaluated. Experimental animals were challenged intradermally with Candida albicans and then administered d-fenfluramine (d-FEN 1 mg/kg per day, i.p.) or a balanced salts solution. At successive time intervals, lymphocytes were derived from the draining lymph nodes and from the dermal sites of active microbial challenge. A CD8+ lymphocytosis was observed in all animals challenged with Candida albicans. The CD8+ lymphocytosis was augmented in animals that received d-FEN. Phenotypically, lymph nodes from d-FEN treated animals showed a marked increase in CD3+ and CD8+ lymphocytes, a modest increase in the numbers of NK1.1+ cells and a decrease in Ig+ lymphocytes. Functionally, lymphocytes from the site of active microbial challenge were capable of direct growth inhibition of Candida albicans. The anti-fungal activity was augmented in the animals that received d-FEN. These results suggest that d-FEN augments the local T lymphocyte response to an important microbial pathogen by increasing the number of T lymphocytes draining the site of microbial infection and by increasing the biological activity of the lymphocytes at the site of the infection.

Direct antimicrobial activity of T cells

T cells are generally thought to contribute to antimicrobial activity either by releasing lymphokines, which recruit and activate other cell types, or by major histocompatibility complex (MHC)-restricted lysis of infected host cells. Recently, it has become apparent that T cells can also mediate antimicrobial activity by direct interaction with microbial targets. Such interactions, which can be either antigen specific or nonspecific, occur in the apparent absence of MHC restriction and do not require the presence of other host cells. Microbial targets recognized by T cells include fungi, parasites and bacteria. Here, Stuart Levitz, Herbert Mathews and Juneann Murphy discuss the direct antimicrobial activity of T cells and speculate on its in vivo relevance.

Growth inhibition of Candida albicans hyphae by CD8+ lymphocytes

We have shown previously that IL-2-activated splenocytes can inhibit the growth of Candida albicans hyphae in vitro. Herein we demonstrate that plastic nonadherent lymphocytes that are CD8+ mediate the antifungal activity. Enrichment for CD8+ cells markedly enhanced the antifungal activity of the IL-2-activated lymphocyte population for C. albicans and the cytotoxic activity of the lymphocytes for an NK-resistant cell line. Depletion of CD8+ cells reduced the lymphocyte population's antifungal activity and cytotoxic activity for the NK-resistant cell line. Enrichment for NK1.1+ cells markedly reduced the antifungal activity of the lymphocyte population for C. albicans and increased the cytotoxic activity of the lymphocytes for an NK-sensitive cell line. Depletion of NK1.1+ cells increased the lymphocyte population's antifungal activity and cytotoxic activity for the NK-resistant cell line. Generation of the antifungal lymphocytes in culture required IL-2 and was not replaced with IFN-gamma. These data show that IL-2-activated CD8+ T lymphocytes exert the greatest amount of antifungal effect against the hyphal form of C. albicans, whereas IL-2- or IFN-gamma-activated NK cells have little or no effect against the hyphae.

Growth inhibition of Candida albicans hyphae by CD8+ lymphocytes

We have shown previously that IL-2-activated splenocytes can inhibit the growth of Candida albicans hyphae in vitro. Herein we demonstrate that plastic nonadherent lymphocytes that are CD8+ mediate the antifungal activity. Enrichment for CD8+ cells markedly enhanced the antifungal activity of the IL-2-activated lymphocyte population for C. albicans and the cytotoxic activity of the lymphocytes for an NK-resistant cell line. Depletion of CD8+ cells reduced the lymphocyte population's antifungal activity and cytotoxic activity for the NK-resistant cell line. Enrichment for NK1.1+ cells markedly reduced the antifungal activity of the lymphocyte population for C. albicans and increased the cytotoxic activity of the lymphocytes for an NK-sensitive cell line. Depletion of NK1.1+ cells increased the lymphocyte population's antifungal activity and cytotoxic activity for the NK-resistant cell line. Generation of the antifungal lymphocytes in culture required IL-2 and was not replaced with IFN-gamma. These data show that IL-2-activated CD8+ T lymphocytes exert the greatest amount of antifungal effect against the hyphal form of C. albicans, whereas IL-2- or IFN-gamma-activated NK cells have little or no effect against the hyphae.

Antibodies specific for the 70-kDa heat-shock protein parallel the development of acute graft-versus-host disease in (DA x LEW)F1 rats

Acute GVHD was induced in unirradiated (DA x LEW)F1 rats by the injection of parental DA lymphoid cells. Serum sequentially derived from such animals was found to contain increased levels of antibodies reactive with 70-kDa heat-shock protein (hsp70). Elevated levels of antibody to hsp70 were detected as early as 7 days and were maximal 14 days after the induction of GVHD. These increased levels of antibodies reactive with hsp70 paralleled the onset of the signs and symptoms associated with the development of GVHD. Increased anti-hsp70 reactivity in GVHD sera was associated statistically with increased levels of hsp70-reactive IgM, IgG2a, and IgG2b. In addition, GVHD sera reacted with a 70-kDa protein found within (DA x LEW)F1 lymphoid tissue. These results demonstrate that increased levels of antibodies to hsp70 parallel the onset and development of GVHD in an acute model and are the first to show that antibodies reactive with hsp70 are associated with an ongoing disease process.

Suppression of the functional activity of IL-2-activated lymphocytes by CGRP

CGRP is a 37-amino acid neuropeptide found in the central and peripheral nervous systems as well as the nerve endings in lymphoid organs. Specific CGRP receptors are present on both T and B lymphocytes. There is increasing evidence that CGRP plays a role in regulation of the immune response. However, few investigations have examined the effects of CGRP on lymphocyte effector functions. In this report, CGRP (0.1 nM-1 microM) was shown to cause concentration-dependent inhibition of IL-2-activated lymphocyte growth inhibition of the fungus Candida albicans and cytotoxic activity for tumor cells. Maximum inhibition of lymphocyte activity by CGRP was 47.4% for the hyphae of C. albicans, 44.8% for a natural killer cell susceptible cell line, and 52.9% for a natural killer cell-resistant cell line. CGRP-mediated inhibition of lymphocyte function was mimicked by 8-bromo-cAMP (1 mM) and was correlated in a concentration-dependent manner with an increase in intracellular levels of cAMP. These increases were potentiated by pretreatment of the lymphocytes with 3-isobutyl-1-methylxanthine (0.5 mM, 10 min), an inhibitor of the cAMP phosphodiesterase. hCGRP 8-37, a selective blocker of the CGRP1 receptor, abrogated the effect of CGRP on lymphocyte function and on intracellular cAMP level elevation induced by rCGRP. CGRP had no direct effect on the capacity of IL-2-activated lymphocytes to adhere to the hyphae of C. albicans. However, both CGRP and 8-bromo-cAMP diminished the capacity of the lymphocytes to release cytoplasmic granular content when stimulated by the hyphae of C. albicans. These data show that CGRP inhibits functional activity of IL-2-activated lymphocytes and suggest that hCGRP8-37 may be a useful tool for assessing the role of CGRP in the immune system.

CGRP in the serum of endotoxin-treated rats suppresses lymphoproliferation

Mouse mesenteric lymph node cells were incubated with concanavalin A (Con A) with or without the rat form of calcitonin gene-related peptide (rCGRP) (0.1 fM-1 microM) +/- human (h)CGRP8-37 (1 microM) for 48 h. DNA synthesis was assessed by [3H]thymidine incorporation. Con A-stimulated DNA synthesis was suppressed by 13, 20, and 30% at 10 fM, 1 pM, and 100 pM of rCGRP, respectively. hCGRP8-37 (1 microM), a selective blocker of CGRP1 receptor, completely inhibited the suppression of DNA synthesis by rCGRP (10 fM-100 pM). rCGRP caused concentration-dependent elevations of cAMP levels, which were potentiated by pretreatment with 3-isobutyl-1-methylxanthine (0.3 mM, 10 min), an inhibitor of cAMP-phosphodiesterase. hCGRP8-37 (1 microM) significantly inhibited cAMP elevations induced by rCGRP at the lower concentrations, but not at the highest concentrations of rCGRP. These data suggest that rCGRP, at circulating levels (1-10 pM), appears to directly interact with receptors on mouse mesenteric lymph node cells that are coupled to cAMP generation, ultimately inhibiting lymphocyte proliferation. To test the involvement of CGRP in suppression of lymphocyte proliferation by serum from endotoxin-treated rats, mouse mesenteric lymph node cells were stimulated with Con A with or without dilutions of endotoxin treated rat serum. At a 1:20 dilution, DNA synthesis was suppressed 30%, at a 1:40 dilution, DNA synthesis was suppressed by 34%, and at a 1:80 dilution, DNA synthesis was suppressed 25%. At all serum dilutions, coincubation with hCGRP8-37 (1 microM) significantly inhibited the suppressive effect of the endotoxin treated rat serum. These data suggest that the immunosuppression observed during endotoxin shock may be due, at least in part, to CGRP in serum.

Macrophage treatment in suckling rat endotoxic shock

Gram-negative sepsis/septic shock in the human newborn continues to be a severe medical problem because of significant mortality and morbidity. Since macrophages detoxify endotoxin, a decreased number of macrophages may contribute to the newborn's sensitivity to endotoxin. In this study, peritoneal macrophages were used for the treatment of endotoxic shock in 10-day-old rats, and 24-hr mortality, plasma glucose, and lactate concentrations were monitored. Peritoneal macrophages were harvested from adult or 10-day-old rats. Caseinate-stimulated macrophages from adult and 10-day-old rats significantly decreased the mortality of 10-day-old rat endotoxic shock from 90% to 37.5% and 44.4%, respectively. Resident macrophages from adult and 10-day-old rats also decreased the mortality from 90% to 12.5% and 45.4%, respectively. Peritoneal macrophages from adult rats significantly ameliorated hypoglycemia during endotoxic shock in a dose-dependent manner. Macrophage treatment decreased plasma endotoxin concentration (P < 0.05). Macrophage treatment was important for host defense.

A quantitative radiometric assay to measure mammalian cell binding to hyphae of Candida albicans

A rapid and reproducible assay has been developed to measure the capacity of lymphocytes to bind to Candida albicans. Lymphocytes that bound to C. albicans were either the large granular lymphocyte cell line, YT, or interleukin-2 activated lymphocytes. Lymphocyte binding was assessed as the associated radioactivity of 51Cr-labeled lymphocytes with preformed hyphae. The assay was sensitive to detection of 0.6 lymphocytes/one hyphal form at one half maximal lymphocyte binding capacity. The assay correlated well with direct microscopic assessment of lymphocyte binding to C. albicans and provided quantitative radiometric data. Although the assay was developed for the assessment of lymphocyte adhesion to C. albicans, it can be used to measure binding of other mammalian cells (e.g., polymorphonuclear leukocytes) to this fungus. In addition, the assay may be used to identify molecules involved in the adhesion of lymphocytes and other mammalian cells to C. albicans.

Quantitative measurement of lymphocyte mediated growth inhibition of Candida albicans

A rapid and reproducible assay has been developed to measure the capacity of lymphocytes to inhibit the growth of Candida albicans. Fungal growth inhibition was assessed optimally as the incorporation of [3H]uridine into preformed hyphae, following interaction of the hyphae with effector lymphocytes. The assay was sensitive to the detection of fungal growth inhibition by lymphocytes at low effector to target ratios and results correlated well with other methods for measurement of anti-C. albicans growth inhibition in vitro. Although the assay was developed for the measurement of lymphocyte mediated anti-fungal activity, other mammalian cell populations can be assayed for growth inhibition of C. albicans as well. The described assay utilizes the enzyme lyticase to reduce the surface binding of C. albicans. The use of this enzyme permits the efficient harvest of large numbers of experimental samples with a multiple automated sample harvester.

Immune cells mediate epinephrine secretion from bovine chromaffin cells in vitro

Potential immunological influences on peripheral catecholamine secretion were investigated by measuring epinephrine secretion from chromaffin cells in vitro in response to cell-free conditioned media from mononuclear cells. Chromaffin cells were isolated from bovine adrenals whereas mononuclear cells were isolated from bovine spleen tissue or whole bovine blood. In secretion experiments epinephrine release and epinephrine remaining in cells was determined such that secretion was expressed as % of total cell content. After 90 minutes exposure to conditioned media, 22.8 +/- 1.1% of content was released compared to 1.7 +/- 0.2% with RPMI media. Secretion after filtration (< 3,000 MW cutoff) was 21.6 +/- 0.9% whereas after boiling and boiling in acid, secretion was 10.2 +/- 0.2 and 4.3 +/- 0.1% respectively. Dialysis (< 3,000 MW cutoff) reduced the 90 min conditioned media-stimulated epinephrine secretion from 22.5 +/- 3.8% to 2.3 +/- 0.3%. Neither atropine nor hexamethonium blockade altered the conditioned media-stimulated epinephrine secretion. These results suggest that mononuclear cells produce a low molecular weight substance--most likely a peptide--that contributes to the stimulation of epinephrine secretion.

Systemic IL-1 and adjuvant treatment of an experimental tumor. II. Immune status during primary tumor challenge

In this investigation, systemic administration of interleukin-1 (IL-1) and local adjuvant therapy were shown to modify immunological parameters associated with the lymphatics draining the site of experimental tumor inoculation. These immunological parameters were shown to be modified early (within 7 days) following tumor inoculation and within the time period of IL-1 administration. IL-1 induced a marked increase in the number of lymphocytes within the brachial and axillary lymph nodes associated with the tumor inoculation site. This increase was characterized by an overall augmentation in the number of CD8+ and CD4+ lymphocytes. In vitro, these lymph node cells showed enhanced proliferation in response to interleukin-2 (IL-2) when compared to non-IL-1 treated animals, and were capable of mounting a potentially greater cytotoxic response for both NK sensitive and NK resistant tumor targets. Without IL-1 administration, temporal and sequential lymph node cellular changes were observed, but were diminished and delayed when compared to the IL-1 treated animals. By adoptive transfer of tumor resistance, lymph node cells from IL-1 treated animals were demonstrated to be tumor-protective in vivo. These results demonstrate that systemic IL-1 induces regional changes in the lymphatics of mice undergoing primary tumor challenge with adjuvant therapy and that these changes result in tumor protection for the host.

Systemic IL-1 and adjuvant treatment of an experimental tumor. I. Immune status following tumor rechallenge

Local adjuvant therapy of weakly immunogenic tumors protects against primary tumor challenge. However, this form of therapy does not produce long-lasting immunity to the tumor. In this study, local adjuvant therapy combined with systemic IL-1 administration produced not only primary tumor protection, but also long lasting immunity to the tumor. IL-1 and adjuvant protected animals resisted rechallenge with tumor as much as 180 days after initial tumor administration. Resistance to tumor rechallenge was IL-1 dose dependent. IL-1 and adjuvant protected animals also exhibited delayed type hypersensitivity reactions which were tumor-specific. Splenic and lymph node cell populations from IL-1 and adjuvant protected animals mounted tumor-specific lymphoproliferative responses. No such responses were observed in animals which had been administered either IL-1 or adjuvant alone. These results demonstrate that systemic IL-1 functions to augment specific immune protection when administered in conjunction with local adjuvant, resulting in long-lasting tumor immunity.

Growth inhibition of Candida albicans by interleukin-2-activated splenocytes

Murine splenocytes, Percoll-enriched low-density lymphocytes, and interleukin-2 (IL-2)-activated lymphocytes were assessed for the capacity to limit the growth of the hyphal form of Candida albicans. No fungal-growth-inhibitory activity was exhibited for C. albicans by either splenocytes or Percoll-enriched lymphocytes. These cells were capable of cytotoxic activity for a natural killer cell-sensitive cell line. However, when cultured for several days with IL-2, splenocytes acquired the capacity to inhibit the growth of the fungus. The appearance of the antifungal activity coincided with the development of cytotoxic activity for the natural killer cell-insensitive cell line. Anti-C. albicans and antitumor activities of IL-2-activated lymphocytes were competitively and reciprocally inhibited by C. albicans and the natural killer cell-sensitive and -insensitive cell lines. The antifungal activity of the IL-2-activated lymphocytes was exhibited against a number of clinical isolates of C. albicans and related fungal species. IL-2-activated human peripheral blood lymphocytes also acquired the capacity to inhibit the growth of C. albicans. These data show that in vitro growth inhibition can be mediated by IL-2-stimulated lymphocytes which are neither fungal strain nor mammalian species restricted in their biological activity.

Growth inhibition of Candida albicans by interleukin-2-induced lymph node cells

Previous reports have demonstrated natural killer cells (NK) to exert growth inhibitory effects against certain fungi, but not against Candida albicans. In this investigation, interleukin-2 (IL-2)-induced lymph node cells with phenotypic and functional characteristics of NK were shown to inhibit the growth of C. albicans. Growth inhibition was evaluated by both the release of 51Cr by the fungus and the inhibition of microcolony growth of the fungus on Sabouraud's dextrose agar. Lymphoid cells derived from C57Bl/6 mice and immediately assessed for hyphal growth inhibition showed little or no activity. However, significant hyphal growth inhibition was produced by lymph node cells cultured with recombinant IL-2. Growth inhibitory activity was dependent upon the concentration of IL-2 and was mediated by nonadherent lymphocytes which lysed an NK-susceptible and to a lesser extent an NK-resistant cell line. Treatment of the IL-2-induced cells with anti-asialo GM1 but not anti-Thy-1 and complement abrogated growth inhibition of C. albicans. These results suggest that IL-2-induced lymph node cells with functional and phenotypic characteristics similar to those of activated NK, mediate in vitro growth inhibition of the hyphal form of C. albicans.

A solid-phase radioimmunoassay to detect antibodies produced by hybridomas to antigens derived from human melanoma cells

A solid-phase radioimmunoassay to detect antibodies that react with antigens derived from human melanoma cells is described. A soluble preparation derived from Nonidet P-40 lysates of tissue-cultured melanoma cells was dried on the surfaces of wells of polyvinyl chloride microtiter plates and fixed with 0.02% glutaraldehyde. Antibody preparations were added and incubated for 18 h at 4 degrees C. The wells were washed and bound antibodies were detected using radioactive Staphyloccoccal protein A (125I-SpA). Optimal conditions are described for all the steps employed. Concentrations of antigen selected, the amount of 125I-SpA employed and the duration of incubation of antibodies with antigen were found to be critical. The assay was sensitive and reproducible, and lent itself to the simultaneous evaluation of many individual antibody samples in a short period of time. The assay was particularly valuable for rapid screening of hybridoma supernatants for antibodies to antigens derived from melanoma cells and from a panel of other tumor and normal cells.

The use of cellular immunoadsorbents to prepare polyclonal antibodies that distinguish between antigens derived from human melanoma cells and autologous lymphocytes

Cellular immunoadsorbents were employed to isolate xenogeneic antibodies that reacted with a restricted group of antigens on human melanoma cells. Melanoma cells and autologous lymphoid cells were grown in tissue culture. Cellular immunoadsorbents were prepared by coupling formalin-treated melanoma and lymphoid cells to diethylaminoethyl cellulose. Rabbits were immunized with melanoma cells and antisera were passed sequentially through immunoadsorbents made of fetal bovine serum, and lymphoid cells. Unbound effluents were then passed through an immunoadsorbent prepared with melanoma cells. Antibodies binding to melanoma cells were eluted and their reactivity to melanoma-derived antigens was tested using a solid-phase radioimmunoassay. Antigens for this assay were NP-40 lysates of melanoma and lymphoid cells and fetal bovine serum. Radioactive Staphylococcal protein A was used to detect binding by the antibodies to the test antigens. The effects of formalin-fixation and storage of melanoma and lymphoid cells were studied. Storage of fixed melanoma cells for periods up to 4 months did not affect their capacity to bind antibodies. A single exposure of formalin-fixed cells to a low-pH elution buffer which was followed by neutralization did not affect binding by these cells. Antibodies isolated in this manner were of the IgG class and reacted with antigens derived from melanoma cells but not from autologous lymphocytes or fetal bovine serum. This study demonstrated the feasibility of using cellular immunoadsorbents to prepare xenogeneic polyclonal antibodies with a high degree of reactivity to antigens derived from human melanoma cells.

Immunotherapy of the guinea pig line 10 hepatocarcinoma with a variety of nonviable bacteria

A variety of heat-killed bacteria were tested for their capacity to induce regressions of established line 10 hepatocarcinomas in syngeneic guinea pigs. Multiple intralesional injections of heat-killed Escherichia coli, Streptococcus mutans, Listeria monocytogenes, and Propionibacterium acnes resulted in complete regression of the tumor in a majority of guinea pigs. Repeated injections of heat-killed Mycobacterium bovis strain Bacillus Calmette-Guérin caused no regressions. Surviving animals were immune to subsequent challenge with line 10 cells but not L2C cells, another syngeneic tumor.

Suppression and immunotherapy of the guinea pig line 10 hepatocarcinoma mediated by heat-killed disrupted Mycobacterium bovis strain Bacillus Calmette-Guérin

Heat-killed Mycobacterium bovis strain Bacillus Calmette-Guérin cells were sonically disrupted, and their antitumor effects against the line 10 hepatocarcinoma in strain 2 guinea pigs were evaluated. When injected together with viable line 10 cells, there was complete suppression of tumor growth. Growth of tumor was also suppressed when line 10 cells were injected contralaterally at the same time as the vaccine mixture. Multiple intratumor injections of sufficient disrupted M. bovis strain B. Calmette-Guérin were therapeutically effective against 74% of 7-day-old tumors and against 40% of 14-day-old tumors. Surviving animals were usually resistant to subsequent rechallenges with line 10 cells but not to syngeneic L2C leukemia cells. By means of a competitive radioimmunoassay, antigenic determinants were detected that were expressed by disrupted but not by intact bacteria.

The use of cellular immunoadsorbents to prepare antibody that distinguishes between syngeneic surface antigens on two guinea pig hepatocarcinomas

Xenogenic antibodies with reactivity for surface determinants of the guinea pig line-10 hepatocarcinoma were isolated by using cellular immunoadsorbents prepared by coupling formalin-treated line-10 cells to diethylaminoethyl cellulose. Antibodies prepared in this manner exhibited a high degree of reactivity for line-10 surface determinants. These antibodies also reacted with surface determinants of the syngeneic line-1 hepatocarcinoma. Further specificity of antibody reactivity to the line-10 hepatocarcinoma was accomplished by passage of the antibodies through cellular immunoadsorbents prepared with syngeneic line-1 hepatocarcinoma cells. By direct binding studies, these antibodies showed significantly reduced reactivity for line-1 cells and no reactivity for guinea pig spleen cells or for the unrelated murine EL-4 lymphoma. By a competitive radioimmunoassay, these antibodies reacted only with determinants expressed on the surfaces of line-10 cells and not on syngeneic line-1, L2C, spleen, thymus; or xenogeneic EL-4 cell surfaces. In a similar manner, line-10-associated antigens were detected in ascites fluid derived from line-10 tumor-bearing animals. The sequential use of immunoadsorbents made of antigenically distinct but syngeneic tumor cells made it possible to prepare antibodies with restricted reactivity for line-10-associated antigens and should be applicable to the isolation of "tumor-specific" antibodies in other systems.

The use of cellular immunoadsorbents to prepare antibody that distinguishes between syngeneic surface antigens on two guinea pig hepatocarcinomas

Xenogenic antibodies with reactivity for surface determinants of the guinea pig line-10 hepatocarcinoma were isolated by using cellular immunoadsorbents prepared by coupling formalin-treated line-10 cells to diethylaminoethyl cellulose. Antibodies prepared in this manner exhibited a high degree of reactivity for line-10 surface determinants. These antibodies also reacted with surface determinants of the syngeneic line-1 hepatocarcinoma. Further specificity of antibody reactivity to the line-10 hepatocarcinoma was accomplished by passage of the antibodies through cellular immunoadsorbents prepared with syngeneic line-1 hepatocarcinoma cells. By direct binding studies, these antibodies showed significantly reduced reactivity for line-1 cells and no reactivity for guinea pig spleen cells or for the unrelated murine EL-4 lymphoma. By a competitive radioimmunoassay, these antibodies reacted only with determinants expressed on the surfaces of line-10 cells and not on syngeneic line-1, L2C, spleen, thymus; or xenogeneic EL-4 cell surfaces. In a similar manner, line-10-associated antigens were detected in ascites fluid derived from line-10 tumor-bearing animals. The sequential use of immunoadsorbents made of antigenically distinct but syngeneic tumor cells made it possible to prepare antibodies with restricted reactivity for line-10-associated antigens and should be applicable to the isolation of "tumor-specific" antibodies in other systems.

Purification of antibodies to bacterial antigens by an immunoadsorbent and a method to quantify their reaction with insoluble bacterial targets

A combination of procedures was employed to develop a radioimmunoassay which quantified the binding of antibodies to antigens of either intact Propionibacterium acnes or to antigens of insoluble extracts derived from the bacteria. Reactive antibody populations were purified by use of bacterial immunoadsorbents which were prepared by coupling P. acnes to diethylaminoethyl cellulose. Binding of antibodies was detected with [125I]staphylococcal protein A ([125I]SpA) and optimal conditions for the assay defined by varying the amounts of antibodies, bacterial antigenic targets and [125I]SpA. In antibody excess, 100% of available [125I]SpA was bound by the target-antibody complexes. However, when antibody concentration was limiting, a linear relationship was demonstrated between per cent specific binding of [125I]SpA and antibodies bound to bacterial targets. These results were achieved only with immunoadsorbent-purified antibody populations and not with hyperimmune sera or IgG. The radioimmunoassay detected subtle antigenic differences and similarities between P. acnes, P. acnes extracts and a variety of unrelated microorganisms.

Single-tube mixed agglutination test for the detection of staphylococcal protein A

A simple, rapid mixed agglutination test using sheep erythrocytes (SRBC) sensitized with rabbit hemolysin and intact viable staphylococci is described for the detection of bound staphylococcal protein A. Soluble protein A was heat extracted from 50 clinical isolates as well as the Cowan I and Wood 46 strains of Staphylococcus aureus and titered by a hemagglutination test using sensitized SRBC and dilutions of soluble protein A. Protein A could be detected in all of these supernatants including that of S. aureus Wood 46, a strain generally considered to be protein A negative. These organisms were later retested by the mixed agglutination test and even those staphylococcal isolates expressing very low heat-extractable soluble protein A concentrations (1:2 titers) were positive, confirming the sensitivity of the test. In a screen of clinical isolates, only 4 of 235 (1.8%) coagulase-positive isolates were negative in the mixed agglutination test. Of 25 coagulase-negative isolates, none yielded a positive reaction.