HIV serology among Italian male military recruits at entrance and discharge.

To evaluate the usefulness of anti-HIV mass screenings, we examined 662 new military recruits and 1353 soldiers being discharged. None of the former and only one of the latter (0.07%) resulted seropositive on repeated ELISA and Western-blot. For comparison we also report the results of routine anti-HIV antibody testing in our diagnostic laboratory: the highest proportion of seropositive subjects was found among symptomatic patients (79%), followed by haemophiliac patients (31%), drug addicts (24%), sexual partners of seropositive subjects (21%), prisoners (5%) and homosexual men (5%). Health care personnel and prison guards were all negative. These data confirm that in Italy HIV infection is still relatively confined to the classic risk groups. While generalized screening during military service seems to be excessive, periodic sample surveys could be very useful to follow the evolution of HIV epidemiology.

Polyclonal B cell activation in ankylosing spondylitis.

The peripheral blood lymphocyte response of patients with ankylosing spondylitis (AS) to several polyclonal B cell activators was investigated. No differences were found in the reactivity to pokeweed mitogen and protein A between patients and controls; in contrast, the peripheral blood lymphocyte response to Staphylococcus aureus strain Cowan I (SAC) was significantly higher in patients with AS than in controls. This responsiveness was not influenced either by the presence of the HLA-B27 antigen or by environmental factors or associated diseases, and it was higher in patients with active AS than in those with inactive disease. The percentage of circulating B cells was normal. The responses to T cell mitogens and the percentages of T cell subpopulations were similar in patients and in controls. The peripheral blood lymphocyte hyperactivity of patients with AS to SAC was associated with an increased in vitro production of immunoglobulins.

B and T lymphocytes regulated by idiotype anti-idiotype interactions inhibit delayed-type hypersensitivity to BCG in mice.

Mice infected subcutaneously with 2 X 10(7) CFU of Mycobacterium bovis strain BCG (BCG) were able to mount a specific DTH response, whereas mice infected intravenously with the same dose of microorganisms were not. The suppression turned out to be mediated by id+ anti-PPD B lymphocytes, which arose very early during the infectious process and induced anti-id B lymphocytes. These cells were found at Day 4 after infection and exerted their effect by activating antigen-specific suppressor T lymphocytes, which affected the efferent phase of the DTH response. These results clearly indicate that the activation of a complex immunosuppressive circuit represents a mechanism by which BCG may interfere with the host's immune response already during the very early phases of infection.

Lymphocyte subpopulation in essential mixed cryoglobulinemia.

Lymphocyte subpopulations were evaluated in 31 patients affected by essential mixed cryoglobulinemia, using OKT3, OKT4, and OKT8 monoclonal antibodies in a cytotoxic assay. The patients with essential mixed cryoglobulinemia had a normal number of OKT3+ and OKT4+ cells but significantly lower values of OKT8+ cells compared to healthy controls. When the OKT4+/OKT8+ ratio was considered, patients could be subdivided into 3 main subgroups: 6 patients had a low OKT4+/OKT8+ ratio, 10 patients had a normal ratio, and 15 had a high ratio. This ratio did not correlate with age, sex, disease duration, low corticosteroid therapy or serological hallmarks of the disease. In contrast, purpura and liver involvement were more prevalent in patients with a normal or high OKT4+/OKT8+ ratio, while lung involvement was more prevalent in patients with a low ratio.

[Pseudomonas aeruginosa: immunotypes and drug resistance]. / Pseudomonas aeruginosa: immunotipi e farmaco-resistenza.

Serotyping of Pseudomonas aeruginosa by Fisher's schema has been used to study the prevalence of particular immunotypes among strains of P. aeruginosa obtained from clinical specimens. About 78% of the isolates were serotypable and about 22% were not. Immunotypes 2 and 6 turned out to be the most prevalent, whereas immunotypes 5 and 7 were the least frequent. Immunotypes 2, 5, 6 and 7 did not vary significantly as far as frequency in the various sources is concerned, with the exception of immunotype 2, which was significantly less frequent in isolates from the expectorated sputum. In such isolates immunotype 3 was significantly more frequent than in other sources, whereas immunotype 4 was significantly more frequent in isolates from the feces. It was next investigated whether a correlation exists between antibiotic susceptibility and particular immunotypes. A high percentage of the non-typable strains and of those belonging to immunotypes 2 and 6 proved to be resistant to the antimicrobial agents tested.

Role of antecedent mumps and reovirus infections on the development of type 1 (insulin-dependent) diabetes.

Type 1 diabetes mellitus is thought to derive from organ-specific autoimmune reactions, probably triggered by environmental factors. In view of the possible involvement of mumps virus and reoviruses in the pathogenesis of autoimmune endocrine disease, serum antibody levels to these viruses were measured in newly-diagnosed diabetic patients aged 5 to 25 years and in matched control subjects. Diabetic patients showed a significantly lower prevalence and reduced titers of antibodies to mumps and reoviruses. By contrast, the antibody response to measles virus (a non-diabetogenic agent) was remarkably similar in the two groups. It is suggested that individuals with an impaired humoral response to some viral agents are at increased risk of developing diabetes when exposed to pancreotropic viruses.

Staphylococcus aureus-induced suppression of contact sensitivity in mice: suppressor cells elicited by polyclonal B-cell activation are regulated by idiotype--anti-idiotype interactions.

Staphylococcus aureus strain Cowan I, a strong polyclonal B-cell activator (PBA), inhibited contact sensitivity to oxazolone in mice when administered 24 hr before sensitization. This suppression was mediated by idiotype-positive (Id+) B lymphocytes, which arose very early during the sensitization process and induced anti-Id B cells. These cells were found at Day 3 of the sensitization process and exerted their effect by activating antigen-specific suppressor T lymphocytes, which affected the efferent phase of the immune response. S. aureus strain Wood 46, which lacks of the ability to act as a PBA, was unable to inhibit contact sensitivity. These results indicate that PBA may play an important role in the regulation of cell-mediated immune reactions.

Polyclonal B cell activators inhibit contact sensitivity to oxazolone in mice by potentiating the production of anti-hapten antibodies that induce T suppressor lymphocytes acting through the release of soluble factors.

Polyclonal B cell activators (PBAs) such as purified protein derivative, lipopolysaccharide, Staphylococcus aureus strain Cowan I (StaCwI), and Pseudomonas aeruginosa inhibit contact sensitivity to oxazolone in mice when given 24 h before sensitization. This suppression, transferable from immunodepressed animals to oxazolone-sensitized recipients with immune serum, has been shown to be due to the early appearance of anti-hapten antibodies. These antibodies elicit T suppressor cells which release soluble factor(s) capable of inhibiting the passive transfer of contact sensitivity.

T suppressor cells as well as anti-hapten and anti-idiotype B lymphocytes regulate contact sensitivity to oxazolone in mice injected with purified protein derivative from Mycobacterium tuberculosis.

Purified protein derivative from Mycobacterium tuberculosis inhibits contact sensitivity to oxazolone in mice when given intravenously 24 to 72 h before the antigen. Transfer experiments showed that various types of suppressor cells occurred in the lymph nodes draining the site of sensitization: (i) anti-oxazolone idiotype + B lymphocytes, found at day 3 after sensitization, transferred suppression to syngeneic recipients at the moment of their sensitization; (ii) anti-idiotype B lymphocytes, found at day 3 after sensitization, transferred suppression to syngeneic recipients when sensitization of these animals had been performed 3 days before cell transfer; (iii) T lymphocytes, found only at day 6 after sensitization, inhibited the passive transfer of contact sensitivity, indicating that they were effective on the efferent phase of the immune response. These results indicate that purified protein derivative from M. tuberculosis interferes with contact sensitivity by activating a complex and multiple immunoregulatory circuit.

Immune reactivity in palindromic rheumatism: response to mitogens.

Lymphocyte responsiveness to various mitogens was studied in patients with palindromic rheumatism. The results show an enhanced lymphocyte reactivity to T-dependent mitogens during the first few days after an acute attack of the disease.

Staphylococcus aureus inhibits contact sensitivity to oxazolone by activating suppressor B cells in mice.

Killed Staphylococcus aureus strain Cowan I cells inhibit contact sensitivity to oxazolone in mice, when given intravenously 24-72 h before sensitization. With transfer experiments it was found that the cells responsible for the suppression are antigen-specific, nylon-adherent, resistant to antitheta serum + C, and sensitive to anti-mouse Ig serum + C. These suppressor B cells bear anti-oxazolone immunoglobulins and appear to exert their suppressive activity by preventing the contact sensitizer from reaching the specific reactive T cells.

Enhancement of the spontaneous development of autoreactive B cells by PPD in mouse peritoneal cell cultures.

The effect of tuberculin purified protein derivative (PPD) on the development of plaque-forming cells (PFC) against bromelain-treated syngeneic mouse red blood cells (Br-MRBC) was studied in peritoneal cell cultures. The finding that PPD enhances the development of PFC to Br-MRBC, even under conditions where cell division is blocked by mitomycin C treatment, suggests that cell proliferation does not represent a necessary prerequisite for differentiation of precursor cells into autoantibody-forming cells.

Immunomodulation by Bacillus subtilis spores.

This study was undertaken in order to investigate the immunomodulatory effect of heat-killed Bacillus subtilis spores as well as of one soluble and one insoluble fraction obtained after their mechanical breakage. The results demonstrate that heat-killed spores, the soluble and the insoluble fraction enhance the primary PFC response to T-dependent antigens such as SRBC and HRBC, but not to T-independent antigens such as Ficoll-TNP. However, the same doses capable of enhancing the production of antibodies against T-dependent antigens were unable to modify the host CMI, evaluated in terms of contact sensitivity to oxazolone.

The suppressive activity of T-lymphocytes and serum factors in burned patients.

This study was performed to investigate the cell-mediated immune response in burned patients with no septic episodes. The results show that burned patients with percentage body burn higher than 20 had an impaired lymphocyte reactivity to phytohaemagglutinin and conconavalin A. This hyporesponsiveness appeared on day 3-4 and in all cases reached its maximum on day 7-8 post burn, while recovery occurred between day 11 and 29 depending on the severity of the injury. The serum from immunodepressed patients was able to inhibit the response to phytohaemagglutinin and conconavalin A of normal lymphocytes. This immunosuppressive activity was present very early after injury (on day 1-2) and before the onset of lymphocyte hyporesponsiveness to mitogens and was no longer detectable on day 7-8 post burn, when patient lymphocytes showed the greatest hyporesponsiveness to mitogens. This late depression was due to T suppressor cells.

Evidence for autoantibody production associated with polyclonal B-cell activation by Pseudomonas aeruginosa.

Experimental infection of mice with Pseudomonas aeruginosa resulted in the polyclonal activation of B lymphocytes, as assessed by the spontaneous plaque-forming cell (PFC) response to trinitrophenyl and sheep erythrocytes. Additionally, a PFC response to bromelain-treated syngeneic erythrocytes (Br-MRBC) could be detected in infected mice, suggesting that P. aeruginosa infection might also induce activation of self-reactive B-cell clones and consequently lead to autoantibody production. Furthermore, in cultures of mouse peritoneal cells, heat-killed P. aeruginosa enhanced the development of anti-Br-MRBC PFC, even under conditions where cell division was blocked, suggesting that the in vitro P. aeruginosa-induced enhancement of anti-Br-MRBC PFC was essentially related to cell differentiation, cell division playing only a minor role. The mechanism of the in vivo and in vitro P. aeruginosa-induced activation of anti-Br-MRBC PFC are discussed.