Central nervous system involvement in HIV infection

Central nervous system (CNS) involvement occurs frequently in patients with the acquired immunodeficiency syndrome (AIDS), but at present only a few reports have addressed the analysis of intrathecal IgG synthesis in human immunodeficiency virus (HIV)-seropositive patients with no signs of HIV-related neurologic syndromes. In this study, intrathecal IgG synthesis was investigated using several techniques in patients with different stages of HIV infection and then correlated with the state of the blood-brain barrier. Almost all patients had specific anti-HIV IgG synthesis within the CNS, suggesting the presence of HIV in the brain. These findings further stress that direct CNS infection occurs early in the course of systemic virus spread.

Cerebrospinal fluid lymphocytes from HIV-infected patients synthesize HIV-specific antibody in vitro

Cerebrospinal fluid lymphocytes from six human immunodeficiency virus (HIV)-infected and three seronegative patients were studied for in vitro synthesis of HIV-specific antibody by means of Western blot analysis of lymphocyte culture supernatants. All the HIV-positive subjects showed in vitro production of HIV-specific IgG, regardless of neurological involvement, while no specific antibody synthesis was detected in seronegative individuals. These data provide the first direct evidence that HIV-specific antibody in cerebrospinal fluid is due to intrathecal synthesis.

In-vitro production of HIV-specific antibody in children at risk of AIDS

To improve on the early diagnosis of human immunodeficiency virus (HIV) infection, 37 children born to HIV-infected mothers and 22 controls were investigated for in-vitro synthesis of IgG antibody directed against HIV components. For 14 of 16 infected children western blot showed HIV-specific IgG in the supernatants of cultures of their peripheral blood lymphocyte cultures. HIV-specific IgG synthesis was detected in cultures from 4 out of 17 seropositive children aged under 15 months with no clinical or laboratory evidence of infection. No HIV-specific IgG production was observed in cultures from 4 uninfected children or 22 controls. The results show that the demonstration of in-vitro production of HIV-specific IgG may help in the early diagnosis of HIV infection in children.

Continuous-wave Doppler of vertebral arteries in noninvasive diagnosis and management of vertebro-basilar TIAs

Continuous-wave Doppler and angiography of the vertebro-basilar system were used in 38 patients with vertebro-basilar transient ischemic attacks. 63 vertebral arteries were studied. Among 47 normal Doppler parameters, 46 were confirmed by angiography. The sonographic diagnostic procedure showed a very high negative predictive value (97.87%), while the positive predictive value was relatively low (56.25%). Data from literature were reviewed. The authors suggest that when Doppler of vertebral arteries is negative, there is a very low probability that a follow-up angiography will reveal pathologic conditions calling for a surgical approach.

2,5-Hexanedione-induced accumulations of neurofilament-immunoreactive material throughout the rat autonomic nervous system

In rats intoxicated with 2,5-hexanedione, nerve fibres supplying virtually all visceral organs showed large numbers of densely immunoreactive accumulations of neurofilament-like material, of fusiform, elongated, smoothly tapering morphology. In the gut, round to oval, morphologically different lesions were also present, and abnormal neurofilament-immunoreactive accumulations were revealed in oesophageal terminal end-plates. An extensive damage to autonomic nerve fibres, which are largely non-myelinated, was thus revealed in 2,5-hexanedione intoxication. The observed diversity in lesion morphology may suggest heterogeneity in cytoskeletal and/or associated proteins among autonomic neurons.

Spontaneous in vitro production of virus-specific antibody by lymphocytes from HIV-infected subjects

In vitro synthesis of IgG directed against HIV components was detected by ELISA and Western blot assay of lymphocyte culture supernatants. Lymphocytes from HIV-infected individuals spontaneously produced antibody against HIV proteins very early in culture, suggesting in vivo activation of HIV-specific antibody-forming cells. The frequency of circulating B cells spontaneously secreting HIV-specific IgG was very high in some cases, but spontaneous HIV-specific antibody synthesis was not accompanied by polyclonal reactivation of B-cell clones of different specificity. The pattern of specificity of the anti-HIV antibody produced in vitro did not reflect the serum pattern consistently. These findings indicate a new approach potentially useful for the study of the immunobiology of HIV infection. The possible implications of the in vitro production of HIV-specific antibody for the diagnosis, prognosis and clinical management of this infection are also discussed.

Study of some early immunological parameters in aging humans

We studied the correlation between the in vitro lymphocyte proliferative response and some early parameters of lymphocyte activation in aged people. While a consistent number of elderly subjects showed significantly decreased proliferative responses to mitogen stimulation, interleukin-1 (IL-1) production and IL-2 receptor/DR antigen expression were comparable to those of young controls. The reduction in IL-2 production observed in some aged donors did not correlate with the decreased proliferative activity in response to mitogen. Moreover, addition to the cultures of recombinant IL-2 was not capable of restoring the proliferative response to normal levels. These data on the whole seem to argue against a primary involvement in age-associated lymphocyte hyporesponsiveness of an alteration in the early phases of lymphocyte activation engaging the complex lymphokine/receptor network.

HIV-mediated immunodepression: in vitro inhibition of T-lymphocyte proliferative response by ultraviolet-inactivated virus

In order to assess whether the human retrovirus HIV, like other animal retroviruses, is endowed with intrinsic immunosuppressive activity, we studied the effects of noninfectious, uv-irradiated virus on in vitro lymphocyte function. uvHIV preparations inhibited T-cell proliferation to mitogens and alloantigens, as well as mitogen-driven IL-2 production. The inhibitory effect, which was not exerted by uv-irradiated HTLV-I, was apparently not due to a decrease in cell viability and was likely associated with thermoresistant viral component(s). The suppression proved to be selective for T-cell responses, while sparing other lymphocyte functions, such as the B-cell proliferative response to a selective B-cell mitogen. The inhibitory effect of uvHIV was not counteracted by a substantial reduction in the number of monocytes or by indomethacin. Moreover, IL-1 production by monocytes was not affected upon virus incubation. On the other hand, the proliferative response of both CD4+ and CD8+ T-cell clones was inhibited by uvHIV, suggesting that T cells represent the actual target for the inhibitory effect. Although a sizeable decrease in IL-2 production was observed following uvHIV incubation, exogenous IL-2 was not capable of reversing the virus-induced suppression of the proliferation. The possibility that the immunosuppressive activity of noninfectious HIV contributes to the T-cell defect in infected patients by mechanisms other than the cytopathic effect on CD4+ T lymphocytes is discussed.

Hemodialysis leukopenia and complement function with different dialyzers

The relationship between leukopenia and the complement system during hemodialysis was re-examined by studying not only the in vivo effects of four different dialyzer membranes (cellulose hydrate, cuprophan, cellulose acetate, and polyacrilonitrile) on leukocyte counts and complement levels, but especially by investigating the effects of these membranes on complement function in vitro. Whereas from in vivo studies no definite conclusions could be drawn, in vitro investigations provided clear-cut information. When more sophisticated technical approaches were undertaken, it became evident that hemodialysis leukopenia has to be thought of in terms of chemotactic factor generation. In fact, a strict correlation was demonstrated between the degree of leukopenia induced by the dialyzers tested and the ability of the relative membrane to generate chemotactic activity in vitro. Moreover, the previously observed ability of polyacrilonitrile membrane to induce a decrement in complement function was due to the ability of polyacrilonitrile to adsorb complement activity and did not correspond to effective complement consumption. This finding explained why polyacrilonitrile dialysis is not accompanied by a decrease in circulating granulocytes. Taken together, our data strongly point to a pivotal role of complement system in the pathogenesis of hemodialysis leukopenia.

Gas-Liquid Chromatographic Determination of Terbuthylazine Technical and Its Formulations: Collaborative Study

Terbuthylazine technical and its 80% wettable powder were analyzed in a CIPAC collaborative study. The content and the identity were determined by gas-liquid chromatography on a column of 3% Carbowax K20M on Gas-Chrom Q, using di-n-pentylphthalate as the internal standard. Results obtained from 27 government, university, and industrial collaborators showed within-laboratory repeatability of 1.3% for the technical and 1.0% for the wettable powder. Reproducibility was 2.1% for both samples. The method has been adopted official first action

Hyperproduction of IgE and T-cell dysfunction in Hodgkin's disease

Serum IgE levels were evaluated in 119 untreated and 112 treated patients with Hodgkin's disease (HD). 38 of the nonatopic untreated patients showed significantly increased (> 300 IU/ml) IgE concentrations. No relationship could be found between increased IgE levels and depressed lymphocyte response to phytohemagglutinin (PHA) or the imbalance of TM and TG lymphocyte subsets. On the other hand, the mean level of suppressor activity elicitable from cells of untreated HD patients by concanavalin A preincubation did not differ significantly from that of healthy control subjects. In contrast, in treated patients, where there was a significant reduction in the number of circulating T lymphocytes, a further depression of the lymphocyte response to PHA, a more marked disproportion of TM and TG cell subsets and a noticeable fall in IgE concentration was found. These data suggest that increased IgE concentrations seen in untreated patients with HD are unrelated to the T-cell defects. They also suggest that hyperproduction of IgE is probably not invariably a consequence of a suppressor cell deficiency.

Different mitogenic activity of soluble and insoluble staphylococcal protein A (SPA)

The response to SPA and Staphylococcus strain Cowan I (StaCw) of highly purified populations of peripheral blood and tonsil human lymphocytes was investigated. Purified T lymphocytes isolated from perpheral blood by E-rosetting were unable to respond in vitro to StaCw. Highly purified B-cell populations from tonsils did not show any proliferative response in the presence of soluble SPA. The addition to highly purified B-cell suspensions from human tonsils of increasing concentrations of autologous T lymphocytes did not induce any increase of thymidine uptake in the presence of StaCw. However, it was able to restore a marked proliferative response of the B-cell cultures to soluble SPA, even though mitomycin-treated T lymphocytes were added. The low response of highly purified peripheral blood T lymphocytes to soluble SPA could be potentiated by the addition of autologous mitomycin-treated B cells, whereas the unresponsiveness of purified T lymphocytes to StaCw was not affected. Mitogenic activity of SPA coupled to Sepharose beads was different from that of soluble SPA and paralleled that of StaCw. These data strongly suggest that insoluble SPA is a T-cell-independent B-cell mitogen in man, whereas soluble SPA, like PWM, exerts its activity on B cells only in the presence of T cells.

Altered proportion of T mu-and T gamma-cell subpopulations in patients with Hodgkin's disease

The ability of peripheral blood lymphocytes from patients with Hodgkin's disease (HD) to form rosettes with ox red blood cells (ORBC) sensitized by anti-ORBC purified rabbit IgM and IgG was investigated. The mean percentage of cells capable of forming rosettes with ORBC coated with IgM (EAIgM-RFC) in the peripheral blood of either untreated or X-ray-treated patients with HD was significantly lower than that of normal individuals. In the same groups of patients with HD the mean percentage of T lymphocytes equipped with receptor for IgG (T gamma lymphocytes), evaluated by a mixed fluorescent rosette assay, was significantly higher than in normal controls. These data suggest that the altered proportion between T mu-and T gamma-cell subpopulations in patients with HD probably represents a disease-related phenomenon.

Receptors for IgM: a feature of subpopulations of both T and B human lymphocytes

Receptors for IgM were detected on peripheral blood and tonsil human lymphocytes by a rosette technique with ox red blood cells (ORBC) coated with anti-ORBC rabbit IgM. It was found that the receptors are very sensitive to handling procedures of cells and to low temperatures. An overnight incubation period at 37 degrees C was the optimal condition for the maximum expression of receptors for IgM, but the use of IgM-free media in these cultures was neither an essential nor favourable factor for an optimal rosette formation, when ORBC heavily coated with rabbit IgM were used. The great majority of chronic lymphocytic leukaemia (CLL) patients presented a high number of EA(IgM)-RFC, either on freshly drawn or cultured lymphocytes. By fractionation procedures of normal peripheral blood and tonsil lymphocytes, it was found that a subpopulation of B cells, like T cells, also posses a lower avidity for IgM than those present on T lymphocytes.

Co-operation between T and B lymphocytes from human tonsils in the response to mitogens and antigens

Purified B lymphocytes obtained from human tonsil cell populations by removing E rosette-forming cells by density sedimentation did not proliferate at three days in response to PHA and Con A, but showed a significant 3H-labelled thymidine incorporation when the PHA response was assessed at day 6 of culture. The 6th-day responses, which was completely abolished by the reduction of T-cell contamination to less than 0-1% by re-rosetting and a second separation, was due in part to a direct activation by PHA of contaminating T cells and in part to a T cell-mediated B-cell response. When purified B cells were stimulated for 3 days by PHA in the presence of an equal number of autologous or homologous mitomycin-treated T lymphocytes a highly significant uptake of 3H-labelled thymidine was demonstrated. The majority of blast cells obtained at day 4 in these cultures were unable to form E rosettes and showed surface immunoglobulin by immunofluorescence stain. This response was markedly decreased by previous treatment of B cells with mitomycin C and it was abolished when B cells were killed by heating at 56degrees C for 1 hr. Purified B lymphocytes from human tonsils did not respond in vitro when cultured for 6 days in the presence of soluble antigens (PPD and Candida). However, a highly significant response to the same antigens could be demonstrated when B cells were cultured in the presence of autologous mitomycin-treated T cells. These models of T-B co-operation could provide an interesting tool for studying the differentiation and antibody production in vitro of human B lymphocytes.

Study of some immunological parameters in untreated patients with Hodgkin's disease

The immunological reactivity of 40 untreated patients with Hodgkin’s disease was studied by some <i>in vitro </i>tests exploring the lymphocyte function, The response of lymphocytes to PHA was markedly depressed in the advanced stages of the disease, but it appeared significantly decreased also in the initial stages when a suboptimal concentration of the stimulant was used to activate the cells in culture. No significant correlation was found between the depressed lymphocyte response to PHA and a particular histologic pattern of the disease, even though patients with lymphocyte predominance and nodular sclerosis usually showed the best responses. The decrease of PHA-stimulability was not dependent on the activity of free serum factors or by the usually high number of phagocytic cells contaminating the standard quantity of lymphocytes in culture. Nor was it due, at least in the initial phases of the disease, to a depletion of circulating cells able to respond to PHA. In fact, the percentage of Ig-bearing lymphocytes in the peripheral blood was usually normal; E rosette-forming cells were present in normal number in the initial stages of the disease and their percentage was markedly decreased only in a very small number of patients with advanced disease. Virtually all the patients with positive delayed-type skin reactions to PPD and Candida, but also many of those without skin reactivity showed a significant <i>in vitro </i>response to the same antigens. The responding capacity in MLC of lymphocytes was not significantly reduced in comparison to that of normal controls; the stimulatory efficacy of the same cells was decreased in some patients but, at group level, did not appear significantly lower of that of normal controls. An increased level of IgE immunoglobulin could be demonstrated in the serum of many patients with HD. The data here reported demonstrate that a functional defect of lymphocytes is a very frequent finding in untreated patients with HD; they also show that of the tests available for the study of lymphocyte function, the PHA-stimulability seems to be the more sensitive and its alteration always precedes the development of T lymphopenia.

In vitro lymphocyte response to the phytomitogens in untreated and treated patients with Hodgkin's disease

In vitro lymphocyte response to phytohemagglutinins (PHA), concavalin A (Con A), and pokeweed mitogen (PW) was evaluated in untreated and treated patients with Hodgkin's disease (HD). The responding capacity to PHA was depressed, though not constantly, in the untreated patients compared with the response to lymphocytes from normal individuals. The depression was more evident, at group level, when the cells were stimulated with suboptimal concentrations of PHA. Radiotherapy constantly induced a strong decrease or a complete loss of the responding capacity of the cells which persisted at low levels for many months. Some years after the initial course of treatment, the response was clearly depressed, but it was better in patients in remission than during relapse. Splenectomy did not affect the responding capacity of the cells. The depressive effect induced by chemotherapy was apparently less marked and persistent than that of radiation. Con A- and PW-induced lymphocyte transformation usually paralleled the PHA-induced response. The depressed response to PHA was not due to an inhibitory activity of HD serum. Washed HD lymphocytes in fetal calf serum were not stimulated better than in autologous plasma, nor were HD sera able to depress the response of normal lymphocytes to PHA, Con A, PW, and PPD. Supernatants from HD lymphocytes cultured for 24 h without any stimulant, and extracts of these cells were also unable to affect the response of normal lymphocytes to PHA.

Studies on allergens of Dermatophagoides pteronyssinus by direct and indirect RAST

Dermatophagoides pteronyssinus (DP) extract was fractionated by Sephadex G-75 and liquid isoelectric focusing (IEF) and the allergenic activity of different fractions was monitored by direct and indirect RAST. The fractionation on Sephadex G-75 showed that the allergenic activity of DP extract was related to wide molecular weight spectrum components, even though the maximum amount was recovered in effluent that contained protein with a molecular weight ranging between 25,000 and 12,500 daltons. By fractionation of the mite extract on IEF, three main peaks of allergenic activity (pI less than 3.0; pI = 4.3 +/- 0.25; pI = 6.4 +/- 0.25) were found. Cross-inhibition experiments showed a high degree of cross-reactivity between allergenic material eluted in very distant regions of molecular weight or isoelectric point. The allergenic activity of unfractionated mite extract and of its IEF fractions was destroyed by pronase - but not by neuraminidase - treatment. These results suggest that DP extract probably contains one main allergen existing in multiple molecular forms rather than several distinct allergens and that a protein moiety of the allergen is necessary for the combination with IgE.

[Immunological aspects of bronchial asthma]

Advances in understanding of bronchial asthma are to be expected from more detailed information on the immuno-pathological mechanisms involved. Reaginic IgE antibodies are responsible for the great majority of extrinsic asthma, but in some cases immune complexes could probably be also important. A great progress has been achieved after reproducible methods for detecting cellular and serum specific IgE antibodies were introduced. Moreover, the immunological and biological changes induced by immunotherapy are better known. Standardization and purification of allergenic extracts is now under study in many laboratories, our own included. As concerns the intrinsic asthma attempts to demonstrate the importance of (auto) immune mechanisms have been performed. The results of these studies are reported.