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In Italy systematic mandatory tetanus immunization of children started in 1968. In a national sample of 241 young males born after 1968 the prevalence of non-immune subjects was 11.2% (5.5% in the North-Centre, 15.9% in the South-Islands; p < 0.02). Comparing these data with the corresponding figure obtained in a previous study of subjects born before 1968 a significant decrease (11.2% versus 32.6%; p < 0.01) is observed. The prevalence of non-immune subjects born after 1968 is significantly (p < 0.01) lower than that observed in subjects born before 1968 by geographical area as well as by area (urban/rural) of residence. These findings indicate that the introduction of compulsory tetanus vaccination for all newborns has favourably affected the immune status of younger Italian men. However, more efforts should still be addressed to decrease regional inequalities in the delivery of health care.

The clinical and immunological responses to typhoid vaccination with parenteral and oral vaccines in two groups of 30 adult male subjects were studied. Specific anti-Salmonella typhi cell-mediated immunity and total or specific anti-lipopolysaccharide faecal immunoglobulin (Ig) A titres in vaccinated subjects were monitored. Cellular antibacterial activity was significantly increased only in orally vaccinated subjects. Serum arming activity and inhibition experiments suggested an IgA-dependent cellular cytotoxicity in those orally vaccinated. In these subjects, a total and anti-lipopolysaccharide faecal IgA increase was observed lasting up to 8 months after completion of the vaccination schedule. In parenteral vaccinated subjects, an early onset transitory increase of IgM rheumatoid factor was observed. Oral vaccine was well tolerated and free of side effects, whereas 65% of parenterally vaccinated subjects reported side effects such as fever, headache, malaise and local tenderness in the injection site.

The effect of carnitine, a drug that plays an essential role in mitochondria metabolism, on some of the most important human polymorphonuclear leucocytes (PMN) activation steps including modulation of adhesion molecule density, reactive oxygen species production, and tumour necrosis factor-alpha (TNFalpha) production was investigated. The capability of carnitine in protecting PMN from deter ioration on storage was also studied. Data shows that carnitine exerts considerable effects on all PMN functions investigated. Although the ultimate effect was often donor dependent, TNFalpha production was exceptional in that carnitine was able to consistently reduce TNFalpha production in Staphylococcus aureus stimulated PMN in a clear dose-dependent fashion. It is concluded that carnitine may represent a useful active agent in situations characterized by PMN mobilization/activation.

Superantigens (SAg) interact with T lymphocytes bearing particular V beta sequences as part of their T cell receptor (TcR). The interaction, however, requires the presence of major histocompatibility complex (MHC) class II molecules on antigen-presenting cell (APC). In peculiar circumstances, MHC class II+ T cell clones (TCC) have been shown to present peptides and selected antigens interacting with antigen-specific TCC in the absence of APC. In this report we studied the capacity of SAg to mediate a T-T cell interaction, investigating the TCC ability to present a panel of staphylococcal enteroxins (SE) independently of the presence of added APC. Upon exposure to a broad range of SE concentrations, MHC class II+ TCC showed an intense proliferative response even in the absence of professional APC. Diverse SE optimally stimulated responder TCC at different concentrations. The proliferation was inhibited by anti-DR monoclonal antibodies, both in the presence and in the absence of APC. The SE activation of TCC in the absence of APC induced the same series of phenotypic variations as that observed following the TCC stimulation with APC. Irradiated TCC efficiently presented membrane-bound SE to responder TCC as well as professional APC. These results show that a single cell of a given clone effectively presents the SE to other cells of the same clone, and provide evidence that SAg can efficiently mediate T-T cell interaction. In addition, the possibility also exists that one cell of the clone can actually undergo an auto-stimulation via SAg-mediated interactions between its own TcR and MHC class II molecule. It has recently been suggested that the V beta-selective depletion of T cells observed in acquired immunodeficiency syndrome (AIDS) patients might be a consequence of the interaction between a human immunodeficiency virus (HIV)-encoded SAg and T cells expressing a SAg complementary V beta. We suggest that the hypothesized HIV-encoded SAg might mediate T-T cell interactions that could play a relevant role in the V beta-selective depletion of T lymphocytes observed in HIV-infected patients.

Human immunodeficiency virus (HIV) infection is characterized by a progressive decline in immune functions. The behavior of B-cell clones specifically engaged in the anti-HIV response could play a relevant role in the pathogenesis of such impairment. The spectrotype observed on isoelectric focusing and reverse blotting after antigen challenge is the serum image of antigen-specific B-cell activity and may provide some insight into Ag-dependent B-cell clone recruitment. In this study, we examined the spectrotype of anti-gp120 antibodies in a group of sera from 56 HIV-infected patients, belonging to groups II, III, and IV of the Centers for Disease Control classification, as well as in a group of 31 sera from 12 patients in a 21-month follow-up evaluation (range 7-36 months). All tested sera were positive for gp120 antibodies on Western blot. In the first group of 56 HIV-infected subjects, only 19 displayed well-focused banding patterns. Among these, the spectrotype was found to be consistently oligoclonal, thus confirming clonal restriction of anti-gp120 antibodies previously described by other investigators. No correlation could be established between a particular spectrotype and phase of the disease. The follow-up evaluation in the second group of 31 sera revealed the tendency in each patient to maintain the same spectrotype throughout the course of the disease. These findings confirm clonal restriction of anti-gp120 antibodies in HIV infection and suggest that the number of B-cell clones recruited in the anti-gp120 response remains stable over the course of the disease, at least in the time range explored by us.

The coordinate expression of CD4 and CD8 antigens defines four major subsets of adult mouse thymocytes (CD4+CD8-, CD4+CD8+, CD4-CD8+ and CD4-CD8-) that represent definite steps in the differentiative pathway of immature T-lymphocytes. Thymocytes from adult C57BL/6 mice were cultured in the presence of ST 789, an L-Arg synthetic derivative of hypoxanthine, (1 to 100 micrograms/ml) or PHA 60.1 to 1 microgram/ml), or both for 48 hours, and then stained with monoclonal antibodies to CD4 and CD8 antigens for dual color flow cytometry analysis. The expression of CD25, was also investigated. ST 789 was ineffective in modifying the distribution of the four thymocyte subsets and did not induce the appearance of CD25 on cortical thymocytes. PHA induced a dramatic dose-dependent decrease of the CD4+CD8+ subset that, however, was neither enhanced nor antagonized by ST 789. We also tested ST 789 for its ability to stimulate intracellular free Ca++ rise in thymocytes. The compound was ineffective in this assay. Conversely, thymocytes promptly responded to PHA stimulation. It is concluded that ST 789 has no effect on normal adult thymocyte differentiation/activation pathway.

Acute respiratory tract infections (ARIS) still represent a major clinical problem during influenza outbreaks. The virus-induced impairment of the immune system favors the entry of opportunistic microorganisms into respiratory tract mucosa. A useful strategy to reduce ARIS is to provide at risk subjects an orally administrable polyvalent vaccine (OPV) comprised of bacteria strains recognised as the major ones responsible for ARIS. For the present study, the main circulating leukocyte populations of a group of healthy subjects receiving OPV were monitored as a marker of immune response. Subjects were investigated immediately before taking OPV (day 0) and 10,20, and 30 days later. Data show that T lymphocytes were induced to enhance the expression of class II MHC molecules, whilst a consistent number of CD4+ lymphocytes lost L-selectin, both phenomena indicating an activation status. OPV administration also modulated important molecules on the membrane of polymorphonuclear leukocytes, namely CD11b and CD16, strongly suggesting an activation of these cells and an enhancement of their defensive capacities. Finally, OPV was found to be able to increase the titer of serum antibodies specific for bacteria strains contained in the vaccine preparation in a portion of individuals. We conclude that OPV is able to consistently influence important immune functions and suggest that this property may be of relevance in preventing ARIS. Also, the present data may help to further our understanding of the mechanisms of OPV activity.

In order to get some insight on the physiology of the immune system during prolonged exposure to hypobaric hypoxia we evaluated the effects of high altitude on the in vivo immune response to a T-independent antigen. A group of 18 men who participated in a scientific project EV-K2-CNR to Mount Poumori, Nepal for 20 d at 4,930 m (16,174 ft) were immunized with a single subcutaneous dose of antimeningococcal vaccine Menpovax A + C (Sclavo) containing 50 micrograms of polysaccharide A (PsA) and 50 micrograms of polysaccharide C (PsC) of N. meningitidis. A group of 18 men of comparable age were vaccinated at sea level. Antibody titers against both polysaccharides were determined by enzyme-linked immunosorbent assay (ELISA) before and 18 d after vaccination. All subjects examined developed a good antibody response and no statistically significant differences were observed between the two groups. Spectrotypic analysis of antibody response to PsC was also performed by isoelectric focusing. No qualitative differences in the antibody response to PsC were found in the hypoxia-exposed group with respect to the control group. A group of 10 BALB/c inbred mice were kept in a hypobaric chamber at 5,500 m (18,000 ft) for 30 d. After 10 d, the mice were vaccinated with 1 micrograms of Menpovax A + C. Anti-PsA and anti-PsC antibodies were quantified by ELISA in sera collected at day 0 and 30. A control group of 10 mice of the same strain underwent the same study protocol but at sea level. Both groups developed a good antibody response to both polysaccharides and no significant differences were observed.(ABSTRACT TRUNCATED AT 250 WORDS)