Effect of prior intragastric antigen administration on primary and secondary anti-ovalbumin responses of C57BL/6 and NZB mice.

We evaluated the effect of antigen feeding on the subsequent primary and secondary anti-ovalbumin (OVA) responses of C57BL/6 and NZB mice. When C57BL/6 mice were given a single 20-mg dose of OVA intragastrically, profound tolerance was observed after challenge, 7 d later, with 125 micrograms of OVA in complete adjuvant or after two injections of 5 micrograms of OVA adsorbed to alum given 7 and 21 d after antigen feeding. OVA-fed NZB mice failed to become tolerant to a primary challenge with OVA in complete adjuvant, but showed a degree of tolerance similar to that of C57BL/6 mice when challenged two or three times with OVA in alum. These studies demonstrate that NZB mice fail to show tolerance at the level of the primary response after antigen feeding; however, they are normally tolerant when a secondary response to a lower dose of antigen is evaluated. This study suggests that, after antigen feeding, different mechanisms of tolerance may be involved in the regulation of primary and secondary responses.

Interleukin-10 functions in vitro and in vivo to inhibit bacterial DNA-induced secretion of interleukin-12.

Bacterial DNA (bDNA) has a number of biologic properties, including the ability to induce interleukin-12 (IL-12) production by macrophages. We studied the role of the regulatory cytokine IL-10 as a potential inhibitor of bDNA-induced IL-12 production. IL-10 concentrations as low as 0.3 ng/ml profoundly inhibited bDNA-induced macrophage IL-12 production as measured by Elispot analysis of IL-12 p40-secreting cells. Additionally, we found that IL-10 inhibited bDNA-induced IL-12 secretion by the macrophage cell lines J774 and RAW 264. Preincubation of splenic adherent cells with IL-10 markedly reduced bDNA-induced transcription of IL-12 p40 mRNA. Interestingly, after 2 h of exposure, bDNA also induces transcription of IL-10 mRNA by splenic adherent cells. The importance of IL-10 in the in vivo regulation of bDNA-induced cytokine secretion was illustrated by the response of mice with disrupted IL-10 genes (IL-10 ko mice) to i.v. bDNA challenge. Compared to +/+ mice, IL-10 knockout (ko) mice exhibited increased numbers of IL-12 and interferon-gamma (IFN-gamma)-secreting cells following either single or repeated challenge with bDNA. These findings indicate that IL-10 plays a key role in regulating bDNA-induced production of inflammatory cytokines.

The influence of lipopolysaccharide content on the apparent B cell stimulating activity of anti-mu preparations.

Anti-mu preparations differ greatly in their ability to stimulate mouse B cells to incorporate tritiated thymidine (TdR). We have found that these differences may be due in part to different levels of lipopolysaccharide (LPS) content. In this report we show that LPS concentrations as low as 0.025 ng/ml stimulate the proliferation of T-depleted (C57BL/6 X DBA/2)F1 (B6D2F1) spleen cells, provided that 5 X 10(-5) M 2-mercaptoethanol is also present. Each of six commercial anti-mu preparations tested for LPS content contained more than this amount. We describe a technique that uses polymyxin B-agarose to remove nanogram quantities of LPS from anti-mu preparations. In B6D2F1 B cells, LPS-depleted anti-mu preparations induced much more uniform tritiated thymidine incorporation than did non-depleted preparations; but there was little difference between the two preparations when tested on B cells from C3H/HeJ (LPS hyporesponsive) mice.

The effect of partial in vivo depletion of CD4 T cells by monoclonal antibody. Evidence that incomplete depletion increases IgG production and augments in vitro thymic-dependent antibody responses.

In vivo depletion or inactivation of CD4 T cells by monoclonal antibody inhibits of T-cell-dependent immune responses and, in some cases, ameliorates clinical autoimmune disease. Impairment of T cell function occurs in situations where mice are treated with relatively large doses of anti-CD4 antibody. When adult (C57BL/6xDBA/2)F1 mice were treated with a low dose of anti-CD4 antibody augmentation of certain thymic-dependent responses occurred. Twice-weekly injections of 50 micrograms of monoclonal antibody GK1.5 for a period of three weeks resulted in a 50% reduction of splenic CD4 T cells. Mice that were partially depleted of CD4 T cells exhibited a 55% increase in serum IgG levels with a 165% increase in serum IgG1. Simulation of spleen cells from these mice with LPS resulted in a significant increase in differentiation of IgG secretion. When spleen cells from partially CD4-depleted mice were challenged in vitro with SRBC, they mounted a direct PFC response that was more than four times the observed PFC response of mice that received either saline or rat IgG. These findings indicate that partial depletion/inactivation of CD4 T cells by in vivo administration of anti-CD4 monoclonal antibody results in a significant augmentation of certain T-cell-dependent humoral responses.

Sociobehavioral influences on smoking initiation of Hispanic adolescents.

PURPOSE: To study the sociobehavioral influences on smoking initiation of Hispanic adolescents over a 3-year period using a national sample. METHODS: Hispanic adolescents (N = 385), ages 15-22 years, from the 1989 and 1993 Teenage Attitudes and Practices Surveys (TAPS I and II), were selected for analyses. Data collected included measures of smoking initiation and attitudes, beliefs toward smoking of the adolescent, and smoking status of family and peers. RESULTS: At the 3-year follow up, 43.4% of nonsmokers at TAPS I had initiated smoking. Risk factors associated with initiating smoking were having male and/or female friends who smoked, and positive attitudes and beliefs towards smoking. Parental and sibling smoking status had little effect on adolescent smoking status. CONCLUSIONS: The peer influence on Hispanic adolescent smoking is consistent with previous research on Caucasian and African-American adolescents. The formation of attitudes and beliefs toward smoking in this population warrants further examination given the influence of attitudes and beliefs on smoking initiation in this study.

Associations between academic performance of division 1 college athletes and their perceptions of the effects of anabolic steroids.

Data on the relationship between academic performance (grade point average) of college athletes and their perceptions of the effects of anabolic steroids on their sport and their performance were collected from Division 1 athletes (N = 1,638) representing 12 varsity sports chosen from five universities nationwide. The response rate was 74%. Analysis yielded differences between athletes with high and low GPAs in perceptions of the effects of anabolic steroids. The lower the GPA, the less likely the athletes were to believe that anabolic steroids are a threat to health, are a problem in their sport, and are addictive. Also, they were more likely to believe that anabolic steroids enhance performance.

Physiological sensations of initial smoking in the development of regular smoking behavior.

This study examined the relationships between adolescents' physiological sensations of smoking during initiation and early experience. For a national sample of a birth cohort of 2,043 adolescents, ages 15 to 22 years at the follow-up, variables of interest included measures of smoking behavior and physiological sensations reported from the initial smoking experience. Analysis showed that adolescents experimenting with smoking were more likely to become regular smokers over three years if they indicated that they felt relaxed, felt dizzy, did not feel sick, and did not cough during the initial smoking experience. Antismoking interventions may impede the transition to regular smoking by helping adolescents interpret the physiological sensations as negative and unhealthy.

Self-reported depression and risk-taking behaviors among Hispanic adolescents.

In assessing the relationships between self-reported depression and certain key risk-taking behaviors among a national sample of Hispanic adolescents (N = 935, ages 12 to 19 years), girls who reported depression were significantly more likely to engage in these behaviors than girls who did not report depression. No significant differences were found among boys (n = 470), although they were more likely than girls (n = 465) to take risks regardless of depressive state. These results suggest that depressive symptoms may be a market for engagement in risk-taking behaviors among Hispanic girls.

Developmental influences of attitudes and beliefs on adolescents' smoking.

This study examined developmental influences of beliefs and attitudes on adolescents' smoking. A national sample (N = 6,900) of adolescents ages 14 to 18 was selected. Data included measures of smoking behavior, beliefs, and attitudes. Although odds ratios show that attitudes and beliefs are predictive of adolescents' smoking status across the ages of 14 to 18 years, no systematic change of the prediction is evident, which contrasts with the psychological developmental model.

Chronic in vivo depletion of CD4 T cells increases both serum IgM levels and the expressed frequency of anti-ssDNA precursors in both NZB and DBA/2 mice.

Chronic depletion of CD4 T cells has been employed as therapy in a number of models of autoimmune disease, including spontaneously autoimmune NZB/W mice. In the present study, we evaluated the influence of CD4 depletion on the production of IgM and IgM anti-ssDNA. Beginning at 8 weeks of age, NZB and DBA/2 mice received 12 weekly injections of monoclonal antibody GK1.5 (anti-CD4) or normal rat IgG. In both strains, CD4 T cell depletion resulted in an increase in serum IgM. Anti-ssDNA precursors, which are increased in NZB mice, were further increased by depletion of CD4 T cells. The DBA/2 mouse expresses anti-ssDNA precursors relatively infrequently; however, CD4 T cell depletion resulted in a significant increase in the expression of these autoantibody precursors as well as an increase in the RNA content of splenic B cells. These results indicate that although CD4 T cell depletion ameliorates clinical manifestations of autoimmunity in some situations, this treatment may also increase serum IgM levels and the production of anti-ssDNA autoantibodies.

The effect of single dose, intravenous cyclophosphamide on the mouse intestinal IgA response to cholera toxin.

The IgA response of gut associated lymphoid tissue (GALT) to enteric pathogens is a vital component of the mucosal barrier. This study describes the effect of cyclophosphamide (Cy) on the IgA anti-CT response of Peyer's patch (PP) and lamina propria cells derived from mice previously challenged enterically with two weekly doses of 10 micrograms CT. Under normal circumstances, both PP and lamina propria responses peaked 7 days after the second dose of CT. To evaluate the effect of a single dose of Cy on this response, mice were given Cy (50 mg/kg) intravenously on days -2, 0, 2 or 7 relative to the initial dose of CT. Cultures of PP and jejunal segments were established 7 days after the booster dose of CT (time or normal peak response). A single dose of Cy suppressed the IgA anti-CT response of PP and, to a lesser extent, jejunal segment cultures only if the drug was given 2 days before the primary dose of CT. This suppression of the anti-CT response was overcome when Cy was given 2 days before CT priming, and CT was administered three times, on days 0, 7 and 14; thus, the effect of Cy was brief and did not appear to promote tolerance to CT. These data show that a single, moderate dose of Cy, given before enteric priming of the GALT, can inhibit the mucosal IgA response to CT. The effect of Cy is relatively brief and dependent upon the time at which the drug is given relative to the induction of the mucosal immune response.

Effect of oral vs. parenteral cyclophosphamide on in vitro IgA and IgG production by murine Peyer's patches and cultured jejunal fragments.

The gut associated lymphoid tissue plays an important role in intestinal defenses, food allergy, oral tolerance, and certain intestinal diseases. This study describes the effect of either oral or parenteral cyclophosphamide on IgA and IgG production in the gut. Mice were treated with cyclophosphamide either IV or PO, and Peyer's patch cell cultures were established to evaluate mitogen induced production of IgA and IgG. To evaluate the effect of cyclophosphamide on the plasma cell rich lamina propria, segments of jejunum were cultured and overnight secretion of IgG and IgA were measured. We found, the secretion of IgA or IgG by jejunal fragments was not influenced by cyclophosphamide (IV or PO). Mitogen induced secretion of IgA and IgG by Peyer's patch cells was markedly decreased 24 hrs after drug administration, with significant recovery by day 7. Cell mixing experiments revealed that a single dose cyclophosphamide reduced the capacity of Peyer's patch B cells to secrete IgA or IgG when co cultured with normal T cells. This study demonstrates that a single dose cyclophosphamide can have profound effects on the gut immune system and that the drug has a similar effect when given either orally or parenterally.

Role of T cells in regulating expression of the B cell repertoire. Anti-ssDNA precursor frequency of DBA/2 B cells is increased in the presence of T cells from NZB mice.

Splenic B cells from DBA/2 and NZB mice were compared with regard to precursor frequency of anti-ssDNA-producing cells. Using a modification of the splenic fragment assay, we show that NZB T cells are capable of increasing the frequency of expression of anti-ssDNA precursors in DBA/2 splenic B cells. When limiting numbers of splenic B cells of DBA/2 origin were adoptively transferred into an irradiated (1200 rad) recipient, the co-transfer of NZB T cells markedly increased the frequency of anti-ssDNA precursors in cultured splenic fragments. The anti-ssDNA produced under these conditions was exclusively IgM and exhibited a high degree of cross-reactivity with TNP and fluorescein. Thus, the increase in anti-ssDNA precursor frequency reflected an expansion of the B cell repertoire to include precursors of polyspecific antibody-producing cells that under normal circumstances are not expressed. The ability of NZB T cells to increase the anti-ssDNA precursor frequency was further defined by the CBA/N immunodeficiency gene xid, in that B cells from DBA/2.xid donors did not exhibit increased anti-ssDNA precursor frequency in the presence of NZB T cells. When NZB splenic B cells were co-transferred with DBA/2 T cells, the anti-DNA precursor frequency of the NZB B cells was not reduced. This study demonstrates that T cells can influence the emergency of B cell clones in an Ag-nonspecific manner. The well documented in vivo spontaneous polyclonal activation of NZB B cells may be secondary to T cell-mediated expansion of the B cell repertoire.

Serum antibody-binding antibodies produced during a primary antibody response.

By using a solid phase radioimmunoassay we have demonstrated that immunization with either polyinosinic.polycytidylic acid (rl.rC) or TNP-Ficoll (both Tl-2 antigens) leads to the late production (day 10 to 15) of an IgG anti-antibody with specificity for the early (day 4 to 5) IgM produced in response to primary immunization. Adsorption of late sera with antigen removes anti-rl.rC or anti-TNP but does not remove anti-antibody. These results show that specific anti-antibody is found in serum during a primary immune response, and its appearance is coincident with a fall in serum anti-antigen. This suggests a possible role of autologous anti-antibody in regulation of a primary immune response.

Analysis of T cell and B cell function in Peyer's patch and lamina propria of New Zealand Black and DBA/2 mice.

We have analyzed gastrointestinal immune function in both DBA/2 and spontaneously autoimmune New Zealand Black (NZB) mice. We have studied both in vitro proliferation and differentiation of Peyer's patch cells and have measured immunoglobulin (Ig) secretion by cultured jejunal segments. Peyer's patch B cells and T cells from both DBA/2 and NZB mice showed similar proliferative responses to Con A and lipopolysaccharide (LPS), respectively. Unlike NZB splenic B cells, isolated Peyer's patch B cells from NZB mice did not spontaneously secrete Ig of any isotype. Seven-day cultures of equal numbers of Peyer's patch T cells and B cells resulted in similar patterns of secretion of IgA, IgG, and IgM in both strains. The addition of Con A to cultures of DBA/2 Peyer's patch cells consistently resulted in a onefold to threefold increase in IgA secretion after 7 days. Con A stimulation of NZB Peyer's patch cells did not produce any increment in IgA secretion. LPS stimulation of Peyer's patch cells from either strain resulted in a similar increase in IgG secretion with little effect on IgA secretion. The in vivo correlate of this finding was seen in the IgA to IgG ratio of Ig secreted by cultured jejunal fragments. In DBA/2 mice the rates of IgA/IgG varied from 2.36 to 4.85, whereas in NZB mice the ratio never exceeded 0.5. These experiments show that defects on the T cell compartment of NZB mice encompass gut-associated lymphoid tissue. The possible relationship of these findings and previously observed defects in oral tolerance is discussed.

Regulation of the primary in vitro response to TNP-polymerized ovalbumin by T suppressor cells induced by ovalbumin feeding.

Spleen cells from DBA/2 mice that received a single feeding of 20 mg of ovalbumin (OVA) 7 days previously were specifically hyporesponsive to primary in vitro challenge with the thymic-dependent antigen TNP-polymerized ovalbumin (TNP-POL-OVA). The tolerance observed in spleen cells from OVA-fed animals was dependent upon OVA-specific T suppressor cells, because splenic T cells from OVA-fed mice suppressed the primary response to TNP-POL-OVA of cultures containing normal T and B cells. The tolerance and suppression was OVA specific, because spleen cells from OVA-fed animals responded well to other antigens (including TNP on another carrier), and splenic T cells from OVA-fed mice did not affect the response of normal T and B cells to sheep erythrocytes. These data confirm the existence of T suppressor cells after OVA feeding and provide a direct means of assaying their activity in a primary in vitro response.

Assessing quality of life in women living with HIV infection.

The purpose of this study was to examine the impact of demographic, clinical and psychosocial variables on health-related quality of life in women living with human immunodeficiency virus infection. Subjects included 82 women 18 years of age or older who were currently seeking treatment at an outpatient clinic. The Medical Outcomes Study-Short Form 20 (SF-20) assessment consisted of patient self-ratings on 20 items measuring six distinct health dimensions. Additional data were collected on age, ethnicity, education, employment status, length of time since HIV diagnosis, CDC stage of disease, total CD4 count, number of symptoms, Karnofsky Performance Scores, social support and discrimination. Multiple regression analyses were performed using each of the six health dimension scores as dependent variables and a combination of ten demographic, clinical and psychosocial variables as independent variables. All of the six multiple regression equations were statistically significant, with R(2) values ranging from 0.35 to 0.44. Age, Karnofsky Performance Score and social support were statistically significantly related to several scale scores (p < 0.05). These results provide baseline data on clinical, demographic and psychosocial determinants of quality of life in a female patient population. Quality of life information can assist programme planners in developing social and medical service delivery for women in the community thus facilitating the development of treatments, programmes and interventions aimed at increasing quality of life for this population.