Fish oil feeding enhances lymphocyte proliferation but impairs virus-specific T lymphocyte cytotoxicity in mice following challenge with influenza virus.

The effect of a fish oil diet on virus-specific cytotoxicity and lymphocyte proliferation was investigated. Mice were fed fish oil (17 g fish oil and 3 g sunflower/100 g) or beef tallow (17 g tallow and 3 g sunflower/100 g) diets for 14 days before intranasal challenge with influenza virus. At day 5 after infection, lung virus-specific T lymphocyte, but not macrophage or natural killer (NK) cell, cytotoxicity was significantly lower in mice fed fish oil, while bronchial lymph node cell proliferation to virus was significantly higher. In mice fed fish oil, spleen cell proliferation to virus was also significantly higher following immunization. The results showed that, despite improved lymphocyte proliferation, fish oil impairs primary virus-specific T lymphocyte cytotoxicity. This impairment may explain the delayed virus clearance that we have previously reported in infected mice fed the fish oil diet.

Alcoholic hepatitis as a T-cell mediated disorder: an hypothesis.

BACKGROUND: The mechanism by which alcohol induces alcoholic hepatitis, the precursor lesion for cirrhosis, has never been elucidated. In particular, direct toxicity has not been proven. This article reviews the hypothesis that a primary target of chronic alcohol ingestion is the T lymphocyte. The lesion in the T lymphocyte is characterized by reduced baseline secretion of cytokines, including tumor necrosis factor-alpha; although characterized by an exaggerated release of cytokines when stimulated by polyclonal activators such as endotoxin. High concentrations of cytokines, especially tumor necrosis factor-alpha, within the liver induce necrosis/apoptosis of hepatocytes. METHODS: Data supporting this hypothesis in rodent models are reviewed. CONCLUSION: A strategic approach for testing this concept in man is defined.

Fish oil feeding delays influenza virus clearance and impairs production of interferon-gamma and virus-specific immunoglobulin A in the lungs of mice.

Ingestion of fish oil can suppress the inflammatory response to injury and may impair host resistance to infection. To investigate the effect of a diet containing fish oil on immunity to viral infection, 148 BALB/c mice were fed diets containing 3 g/100 g of sunflower oil with either 17 g/100 g of fish oil or beef tallow for 14 d before intranasal challenge with live influenza virus. At d 1 and d 5 after infection, the mice fed fish oil had higher lung viral load and lower body weight (P < 0.05). In addition to the greater viral load and weight loss at d 5 after infection, the fish oil group consumed less food (P < 0.05) while the beef tallow group was clearing the virus, had regained their preinfection weights and was returning to their preinfection food consumption. The fish oil group had impaired production of lung interferon-gamma (IFN-gamma), serum immunoglobulin (Ig) G and lung IgA-specific antibodies (all P < 0. 05) although lung IFN-alpha/beta and the relative proportions of bronchial lymph node CD4+ and CD8+ T lymphocytes did not differ between groups after infection. The present study demonstrates a delay in virus clearance in mice fed fish oil associated with reduced IFN-gamma and antibody production and a greater weight loss and suppression of appetite following influenza virus infection. However, differences observed during the course of infection did not affect the ultimate outcome as both groups cleared the virus and returned to preinfection food consumption and body weight by d 7.

Erythrocytes enhance the immunogenicity of oral vaccination with gamma irradiated influenza virus: increasing the dose of irradiation results in a significant diminution of lung IgA response.

Previous studies have demonstrated that the ability of gamma-irradiated whole influenza virus to prime for specific anti-influenza antibody responses was dramatically enhanced when delivered in a complex with chicken red blood cell ghosts (cRBC). The purpose of this study was to investigate the effect of increasing the dose of gamma irradiation used to inactivate A/Queensland/6/72 virus on the ability of the virus-cRBC complex to prime for specific influenza responses. Spleen cell proliferation studies confirmed the enhancing effect of the cRBC carrier for oral vaccination with irradiated virus. Cells from mice vaccinated with 30 kGy-irradiated virus only did not respond to influenza stimulation in vitro, whereas cells from mice vaccinated with irradiated virus+cRBC showed significant increases in proliferation to antigen exposure. No significant antibody response or challenge virus clearance was observed in mice orally vaccinated with irradiated (13.1 or 30 kGy) virus alone, even when the dose was increased significantly. Oral vaccination with live virus (+/-cRBC) primed for significant influenza specific IgA responses in the lungs, in addition to IgG responses in the lungs and sera. The dose of irradiation used to inactivate the virus was found to be critical to the profile of antibody response when the virus was delivered in a complex with cRBC. Oral vaccination of Swiss mice with 13.1 or 30 kGy virus (+cRBC) primed for significant serum and lung IgG responses. Lung IgA responses for 13.1 kGy+cRBC vaccinated mice were detected, but 30 kGy+cRBC vaccinated Swiss and CBA/H mice had no significant lung IgA response. The abrogation of IgA response, however, did not lessen the clearance of live challenge virus in outbred mice, suggesting a primary role for IgG and/or CTL response in the control of influenza virus infection post oral vaccination. To ensure direct comparison of virus alone and virus+cRBC treatments, the concentration of virus complexed to the cRBC was determined.

Isolation and functional characterization of T cells from human sputum.

T cells play a central role in the control of inflammation in the bronchial mucosa through the elaboration of proinflammatory cytokines. This study describes a method for the isolation and cloning of T cells from sputum of adult subjects. In sputum, T cells were of a minor population (< 2% of total cells), and not all expressed activation markers for CD29 (very late antigen-1 (VLA-1)), IL-2R and HLA-DR. When cultured in the presence of rIL-2 for 7 days and then cloned by limiting dilution, the ratios of CD4+ and CD8+ T cell clones (TCC) generated reflected those of CD4+ and CD8+ T cells found in sputum. CD4+ TCC and primary CD4+ T cell populations produced a range of proinflammatory cytokines when stimulated with immobilized anti-CD3 MoAb. Analysis of mRNA messages by reverse transcriptase-polymerase chain reaction (RT-PCR) and Southern blot showed good correlation with the production of cytokine in culture supernatants. A correlation existed between the pattern of cell infiltrate in sputum and the cytokine profile.

Sigma binding site ligands inhibit cell proliferation in mammary and colon carcinoma cell lines and melanoma cells in culture.

Recent evidence suggests a role for sigma (sigma) binding sites in maintenance of cell growth and/or proliferation. The present study examines, for the first time, the effect of sigma binding site ligands on in vitro growth of tumour cells derived from human mammary adenocarcinoma (MCF-7, MDA) and colon carcinoma (LIM 1215, WIDr), and melanoma (Chinnery). Addition of the sigma ligands haloperidol, reduced haloperidol, 1,3-di(2-tolyl)guanidine (DTG), (+)- and (-)-N-allylnormetazocine (SKF 10,047), (+)- and (-)-pentazocine and rimcazole at 6.25, 12.5, 25, 50, 100 microM at the beginning of culture or 24 h later, inhibited cell proliferation in a dose-dependent manner. Light microscopy revealed cell detachment, rounding and cell death. The potency of sigma ligands on melanoma cells was rimcazole > reduced haloperidol > haloperidol = (+)-pentazocine, whereas DTG and (+)- and (-)-SKF 10,047 and (-)-pentazocine had no effect even at 100 microM. In contrast, in MCF-7 cells, rimcazole > reduced haloperidol > haloperidol > (-)-pentazocine > DTG > (+)-pentazocine > (+)-SKF 10,047 > (-)-SKF 10,047. For colon cancer cells, reduced haloperidol > DTG > haloperidol = (-)-pentazocine = (+)-pentazocine = (+)-SKF 10,047. Of all the ligands tested, rimcazole and reduced haloperidol were the most potent inhibitors of cell proliferation. With the exception of one slow-growing colon cancer cell line (LIM 1215), the order of sensitivity of various cell lines to reduced haloperidol, SFK 10,047, DTG, haloperidol and (+)- and (-)-pentazocine was colon carcinoma > mammary adenocarcinoma > melanoma, whereas to rimcazole, the sensitivities of mammary adenocarcinoma and melanoma cells were comparable. The effect of sigma ligands in MCF-7 and melanoma cells was not due to blockade of dopamine D1 and D2 receptors, serotonin (5-HT2) receptors, N-methyl-D-aspartate (NMDA)/phencyclidine receptors, beta-adrenoceptors or opioid receptors, since 100 microM SCH 23390, raclopride, mianserin, (+)-MK-801, propranolol and 1 microM naloxone respectively, were ineffective. However, mianserin and raclopride were inhibitory to melanoma cells and one colon carcinoma cell line, respectively. Taken together, the results are consistent with the recent observation that sigma binding sites may play a role in cell growth and/or cell proliferation.

A novel particulate influenza vaccine induces long-term and broad-based immunity in mice after oral immunization.

The immunogenicity of a novel particulate oral influenza vaccine was examined in terms of antibody response and protection in mice. Oral immunization with chicken erythrocytes (CRBC) adsorbed with gamma-irradiated influenza A virus induced high levels of immunoglobulin G antibodies and protection in the lung compared with gamma-irradiated virus administered alone or CRBC. Immunoglobulin A antibodies were the predominant antibodies in nasal washings, and their presence did not correlate with protection as well as immunoglobulin G antibodies. Immunity was not specific for the immunizing virus subtype, as antibodies and enhanced lung clearance of virus were demonstrated with different virus subtypes. However, mice were not protected when challenged with live influenza B virus. The antibody response and the degree of protection were dependent on both the concentration of virus adsorbed to CRBC and number of CRBC adsorbed to virus. Virus-adsorbed CRBC given subcutaneously failed to induce antibodies or protection. Oral immunization with A/Qld/6/72 (H3N2) virus gave a high level of protection over 12 weeks, which could be demonstrated with different subtypes. Protection correlated with antibody levels in the lung determined by both enzyme-linked immunosorbent and hemagglutination inhibition assays, although the levels detected by the latter declined over time.

Induction of antigen-reactive and IL-2 receptor bearing cells following oral immunization in humans.

A human model of oral immunization using two forms of HI antigen preparation was studied. Oral immunization with killed HI (monobacterial) or HI in a polybacterial mix (polybacterial) induced an enhanced antigen-driven proliferative response in circulating PBL of normal subjects as well as an increase in the precursor frequency of HI antigen-specific cells using limiting dilution analysis. However, the proliferative response was better maintained at a high level in subjects after completion of immunization with the polybacterial vaccine, whereas the response was small and transient following oral immunization with the monobacterial vaccine. Clonal analysis of the proliferative response demonstrated that the precursor frequency of HI antigen-specific cells in the circulating pool was not expanded to account for the differences, despite repeated ingestion of the vaccine. An analysis of PBL following oral immunization using anti-TAC monoclonal antibody revealed an increase in the number of IL-2 receptor-bearing cells in subjects orally immunized with the polybacterial vaccine, with maximal numbers occurring at day 62 when the number of precursors fell but the proliferative response remained high. This suggests that the enhanced and sustained proliferation in bulk cultures is due in part to a contribution to the overall proliferation by in vivo polyclonally-activated IL-2 receptor positive cells which proliferate in the presence of IL-2. Taken together, the results obtained are consistent with the concept that 'restricted' cell activation may be important in the mechanism of selective protection found following oral immunization with monobacterial HI vaccine.

Interleukin-2 is required for the induction of erythrocyte--specific antibody responses in human lymphocyte cultures.

The involvement of interleukin-2 (IL-2) in the generation of human antibody responses was studied using the pokeweed mitogen (PWM)-induced sheep erythrocyte-specific plaque-forming cell (SE-PFC) response of cultured tonsilar lymphocytes. IL-2-containing supernatants from phytohemagglutinin-stimulated human spleen or tonsil cells or the cloned human T cell line JURKAT were capable of replacing the requirement for PWM in the generation of SE-PFC and resulted in a more prolonged response than that observed with PWM. This effect of IL-2-containing medium was dependent on the presence of SE-derived antigens and was not due to the induction of polyclonal antibody synthesis. When purified by gel filtration the SE-PFC-inducing activity co-eluted with IL-2 with an apparent molecular weight of approximately 15,000 (range, 8,000-20,000). Selective removal of IL-2 from crude or partially purified IL-2 preparations by extensive adsorption with activated murine thymocytes or an IL-2-dependent T cell line completely eliminated SE-PFC-inducing activity, indicating that IL-2 itself was necessary for the effect. The question of whether or not this effect was mediated through T cells is discussed.

Immunoglobulin-secreting cells in SLE: correlation with disease activity.

Peripheral blood lymphocytes which contain and secret immunoglobulin were identified by fluorescent staining and a reverse hemolytic plaque assay. Significantly increased numbers of these cells were found in patients with active systemic lupus erythematosus compared with patients with rheumatoid arthritis, bacterial infections and normal controls. The increased numbers of these circulating activated B cells closely correlated with clinical and laboratory indices of disease activity, indicating their potential value in the management of lupus patients. However, the demonstration of pseudo-plaques in assays of lymphocytes from some lupus patients emphasizes the need to establish the true secreting nature of the plaques detected.

The proliferative capacity of human T lymphocyte subpopulations in a continuous culture system.

The continuous growth of subpopulations of human T lymphocytes was investigated using a culture system containing conditioning factors from mitogen-stimulated lymphocytes. Cultures of purified peripheral blood lymphocytes rapidly became enriched for T lymphocytes, detected as sheep erythrocyte rosette-forming cells, and could be maintained for up to a month in an actively growing state. Subpopulations of T lymphocytes bearing Fc receptors for IgM(T.M) or IgG(T.G) could not be detected in these cultures unless the cells were first washed and cultured for 3 days in medium devoid of conditioning factors. During this second culture step, many of the cells reverted from a large, blast-like state to a small lymphocyte morphology and proportion of the T lymphocytes re-expressed Fc receptors. The proportions of T.M and T.G lymphocytes so detected remained constant throughout the continuous culture period indicating that the system permitted the proliferation of all T lymphocytes. Fractionation studies supported this conclusion by demonstrating that purified T, T.M and T.G but not B lymphocyte populations proliferated when cultured in the presence of conditioned medium. The majority of cells in cultures of purified T.M lymphocytes re-expressed IgM Fc receptors following reculture in unconditioned medium. However, the re-expression of IgG Fc receptors by cultured T.G lymphocytes could not be achieved.

Nature of the union between sheep red blood cells and T lymphocytes.

Calcium ions acting as salt bridges between the receptor on T lymphocytes and the negatively charged sites on sheep red blood cells (SRBC) are probably involved in rosette formation. Evidence to support this hypothesis includes the results of manipulating the ionic concentration of Ca2+free incubation medium and rosette inhibition in the presence of EDTA. Optimal rosette formation occurred when NaCl was the supporting electrolyte and the ionic strength was 100-150 mM. Neither KCl, CaCl2, MgCl2 nor Na2SO4 were effective as supporting electrolytes. SRBC pretreated with neuraminidase showed improved rosette formation of lower ionic strength than control cells.