Sheep red cell binding to human lymphocytes treated with neuraminidase; enhancement of T cell binding and identification of a subpopulation of B cells.

Neuraminidase treatment of normal human lymphocytes enhances their capacity to form SRBC rosettes; more red cells are bound and the rosettes are more stable. Under these conditions approximately 90% of peripheral blood lymphocytes form rosettes. In addition to the effects on T cells, another population of lymphocytes which possess surface immunoglobulin and have the Fc receptor acquire the rosette-forming property after neuraminidase. This subpopulation of 'B' cells represents approximately half of the lymphocytes with surface immunoglobulin but is not found among the leukemic lymphocytes of patients with chronic lymphocytic leukemia. Electron microscope observations indicate close approximation and intimate association of the red cell and lymphocyte membranes after neuraminidase.

Scanning electron microscopy of human lymphocyte-sheep erythrocyte rosettes.

Human lymphocytes of known B or T derivation were examined by scanning electron microscopy (SEM) before and after rosetting with SRBC. After collection of the cells onto silver membranes the samples were prepared for SEM by the critical point drying method. Sheep RBC frequently underwent sphero-echinocyte transformation and multiple projections extended from their surfaces. This was readily noticeable after storage of SRBC in the cold and washing in Hanks, but more prominent after rosetting. These erythrocyte surface alterations were less apparent when freshly withdrawn cells were used. Spontaneous sheep erythrocyte rosettes (E-R), a marker for human T lymphocytes, were prepared with normal peripheral blood lymphocytes (PBL), thymic cells, and cultured T cells. EAC-rosettes (EAC-R), used to identify B lymphocytes with complement receptors, were prepared with normal PBL and cultured B cells. The majority of rosetting T lymphocytes had generally smooth surfaces while about 20% had an intermediate number of microvilli and 15% were more villous and indistinguishable from villous B cells. Studies of rosetting thymocytes and cultured T cells however indicated that the surface of some T cells alters on rosetting, becoming more villous and thus account for the higher numbers of villous T cells seen in E-rosettes. Point to point contact sites between SRBC and T lymphocytes were more frequent than broad zones of attachment. The majority of rosetting B lymphocytes had multiple microvilli, about 25% had a moderate number of microvilli and less than 10% had smooth surfaces similar to those of most T cells. Areas of contact between EAC and B lymphocytes were frequently broad zones of attachment. The study confirms that in many cases B and T lymphocytes can be distinguished by their surface architecture as seen under the SEM; however, about 20% of rosetting B and T cells have similar surfaces with intermediate numbers of surface microvilli and cannot be distinguished by SEM without parallel immunologic identification.

Identification of human B and T lymphocytes by scanning electron microscopy.

In this study a variety of human lymphocytes of known B or T cell type, obtained from multiple sources, were prepared for scanning electron microscopy (SEM) by the critical point drying method. Distinction between normal B and T lymphocytes was relatively easy in most instances, on the basis of their surface architecture. Using immunological methods, between 20 and 30% of normal peripheral blood lymphocytes (PBL) were identified as B cells and from 69 to 82% as T cells. SEM results showed that 20% of the PBL had a complex villous surface and approximately 80% of cells were smaller and had a relatively smooth surface. Comparison of the above data and enrichment of B cells from PBL, by centrifugation after T cell rosettes had formed, indicated that the "villous" cells were B lymphocytes and the "relatively smooth" cells were T lymphocytes. T cells obtained from two human thymuses were also of the generally smooth cell type. Further evidence for the distinction of B and T lymphocytes, on the basis of surface morphology, was obtained from the examination of cultured lymphoid cell lines of known B or T cell derivation. Cells from cases of chronic lymphocytic leukemia also provided support for the above interpretations. Five of six untreated cases were clearly of B cell type by immunologic and SEM criteria. One unusual case showed the presence of T and B lymphocytes in almost equal numbers by SEM and a mixture of B and T cells by immunologic markers. An additional case that had received chemotherapy showed numerous atypical cells that were difficult to classify by SEM. Detailed examination of the smoother T cells showed that at least half of them had a moderate number of surface digitations and a small proportion had an intermediate surface morphology with a relatively large number of surface digitations. The latter presented difficulties in classification and may correspond to different stages of differentiation and represent subpopulations of lymphocytes. The distinction between human B and T lymphocytes on the basis of their surface architecture can be made by SEM of critical point dried samples, with relative ease in most but not all instances. The effects of stimulation, cell cycle, differentiation, intercellular contact, and density of cell population, on the surface architecture of lymphoid cells, remain to be determined.

Analyses of lymphocytes from patients with rheumatoid arthritis and systemic lupus erythematosus. Occurrence of interfering cold-reactive antilymphocyte antibodies.

Large percentages of the lymphocytes from some patients with rheumatoid arthritis and systemic lupus erythematosus were densely covered with Ig demonstrable by immunofluorescence, which was occasionally present in the form of caps. The amount and character of the Ig staining depended largely on the procedures used in the isolation and washing of the lymphocytes. Cold-reactive antilymphocyte antibodies present in many sera wre primarily responsible for these variations. Overnight culture of the lymphocytes proved to be an efficient procedure for the removal of adsorbed antibody. Some evidence was also obtained for the presence of circulating immune complexes and exogenous rheumatoid factor molecules on the lymphocyte surface. Thus on freshly isolated cells the demonstration of surface Ig proved to an unreliable marker of bone marrow-derived (B) cells in these disease: the actual percent of B cells with intrinsic surface Ig was often markedly decreased. In patients with systemic lupus erythematosus, this reduction was in agreement with the low numbers of cells that had a receptor for aggregated IgG. The mean percentage of thymus-derived (T) cells in both diseases was slightly greater than the normal level.The concentrations of lymphocytes in joint fluids from patients with rheumatoid arthritis were often greater than levels found in blood. T cells primarily accounted for this increase. The T cells typically formed unusually dense rosettes with sheep erythrocytes. B lymphocytes were proportionally much diminished. Evidence was obtained for the existence of a major joint fluid lymphocyte population that lacked all assayed surface markers.

Chronic immune activation associated with intestinal helminth infections results in impaired signal transduction and anergy.

Helminthic parasites cause widespread, persistent infections in humans. The immigration of Ethiopians to Israel (a group denoted here by "Eth."), many of them infested with helminths and in a chronic immune-activation state, enabled us to investigate the effects of such immune activation on immune responses. We studied the immune profile and immune functions of 190 Eth. and Israeli non-Eth. (Isr.) highly, partially, or non-immune-activated individuals. Immune cells from highly immune-activated individuals were defective in several signaling responses, all of which were restored gradually following anti-helminthic treatment. These cells showed poor transmembrane signaling, as seen by the phosphorylation of various tyrosine kinases and of the MAPK kinases, ERK1/2 and p38; deficient degradation of phosphorylated IkappaBalpha; increased expression of cytotoxic T lymphocyte-associated antigen 4 (CTLA-4), which appears to block proliferative responses in these cells; decreased beta-chemokine secretion by CD8(+) cells after stimulation; and reduced proliferation to recall antigen stimulation. Highly immune-activated individuals also showed decreased delayed-type skin hypersensitivity responses to recall antigen before deworming. These findings support the notion that chronic helminthic infections cause persistent immune activation that results in hyporesponsiveness and anergy. Such impaired immune functions may diminish the capacity of these individuals to cope with infections and to generate cellular protective immunity after vaccination.

Organ specific neoantigens reactive in the leukocyte adherence inhibition assay: affinity purification of human colon carcinoma antigen and its cross-reactive protein using monoclonal antibodies.

A monoclonal antibody (mAb) was prepared against a semipurified preparation of an organ specific neoantigen (OSN) reactive in the leukocyte adherence inhibition (LAI) assay. The mAb (LC20.1) induces a positive LAI response when incubated with leukocytes of normal individuals in the presence of OSN derived from either human colon or lung carcinoma cell lines. Absorption of crude OSN preparations from these cell lines on immobilized LC20.1 mAb eliminates all the LAI reactive material suggesting that the mAb recognizes a common determinant on OSN from both colon and lung carcinomas. The LC20 mAb was used to affinity purify the colon cancer OSN as well as a cross-reactive normal protein from the urine of colon cancer patients and healthy donors, respectively. The colon cancer OSN and normal cross-reactive protein display an apparent molecular weight of 29,000, have a similar linear tryptic peptide map, and are indistinguishable by isoelectric focusing analysis. Regardless of the molecular similarity, only the colon cancer OSN preparation could induce a positive LAI when incubated with leukocytes of colon cancer patients. Seven additional anti-colon cancer OSN mAbs were prepared against purified material. These mAbs can be divided into three groups, each of which recognizes a distinct antigenic determinant that is shared by the colon cancer neoantigen and its cross-reactive normal protein.

Immune changes in male homosexuals--predisposing factors for HIV seroconversion.

Israel is still a low incidence country for AIDS and thus the temporal relationships between various cofactors and HIV infection can be more easily determined. We have studied a cohort of 243 asymptomatic male homosexuals (MHS) during the last 4 years. At the beginning of the study, 40% had significant decreases in the peripheral blood lymphoid populations, signs for reactivation of CMV and EBV infections, and elevated serum levels of interferon. There was no difference in the prevalence of these immune derangements between seropositive and seronegative individuals. In the course of 4 years' follow-up, the prevalence of these immune derangements has remained the same though being significantly more severe in the HIV seropositive subjects. HIV seroconversion did not exceed 8% (about 2% annually) and was related to the immune impairments found when first seen at the beginning of the study. The results suggest that immune impairments are common among asymptomatic MHS, precede HIV infection, and probably contribute to the increased risk for AIDS among male homosexuals.

Genotypic variation of HIV-1 reverse transcriptase and protease: comparative analysis of clade C and clade B.

OBJECTIVE: To compare drug-resistant variants from untreated (naive) and treated patients infected with clade B or C virus. METHODS: Consecutive samples (165) from patients throughout Israel were analyzed. All those in the treated group were failing highly active antiretroviral therapy. RESULTS: There were 87 clade B (14 naive) and 78 clade C (20 naive) [corrected] with significant differences in the prevalence of known drug-resistance mutations between the clades: in naive patients in the protease region M36I 7% and 95% (P < 0.0001), K20R 0% and 27% (P = 0.063), A71V 18% and 0% (P = 0.063), M46I 0% and 13%, and V77I 18% and 0% (P = 0.063), respectively, and in the reverse transcriptase region A98G/S 0% and 20% (P = 0.12), respectively. Most clade C viruses also showed significant differences from clade B consensus sequence at additional protease sites: R41K 100%, H69K/Q 85%, L89M 95% and I93L 80% (P < 0.0001). There were also significant differences (P < 0.03 to < 0.0001) in treated patients in clades B and C: in the protease region L10I 40% and 12%, M36I 26% and 95%, L63P 67% and 40%, A71I 38% and 7%, G73I and V77I 18% and 0%, I84V 16% and 3%, and L90M 40% and 12%, respectively; in the reverse transcriptase M41L 41% and 17%, D67N 41% and12%, K70R 30% and 7%, T215Y 48% and 29%, K219Q 21% and 7%, and A98G/S 3% and 24%, respectively. CONCLUSION: Significantly differences between clade B and C viruses may be associated with development of differing resistance patterns during therapy and may affect drug utility in patients infected with clade C.

A sex comparison of rates of new AIDS-defining disease and death in 2554 AIDS cases. AIDS in Europe Study Group.

OBJECTIVES: To compare the development rate of new AIDS-defining diseases between 566 women and 1988 men with AIDS who were infected with HIV via the same routes (mainly by sharing drug injecting equipment and heterosexual sex). DESIGN: Information on patient follow-up after AIDS diagnosis was obtained by retrospectively reviewing case notes. METHODS: The 2554 men and women were followed from the time of AIDS diagnosis as part of the multicentre AIDS in Europe study, which examined AIDS cases diagnosed at 52 centres in 17 European countries between 1979 and 1989. Incidence of AIDS-defining diseases and demographic variables were recorded for all patients and CD4 lymphocyte count at the time of AIDS diagnosis for approximately half the patients. RESULTS: Only toxoplasmosis and herpes simplex virus ulceration showed statistically significant differences in occurrence rate between women and men [relative risks (RR), 1.51 and 3.44; 95% confidence interval (CI), 1.51 1.09-2.08 and 3.44 1.92-6.23, respectively] which remained after adjusting for imbalances in other variables. For both diseases, the additional absolute rate in women was approximately three per 100 person-years at risk. Survival after AIDS diagnosis was also similar between the two sexes (RR, 0.96; 95% CI, 0.86-1.08). CONCLUSION: There appears to be little difference between women and men in the clinical course of AIDS.

Increased soluble tumor necrosis factor receptor expression and release by human immunodeficiency virus type 1 infection.

High levels of circulating soluble tumor necrosis factor receptors (sTNF-R) are associated with HIV-1 infection and disease. To understand better this association, we have investigated p55 and p75 TNF-R expression on peripheral blood mononuclear cell (PBMC) subsets and in the promonocytic cell line U937, with or without HIV infection. Using flow cytometry and monoclonal antibodies both to sTNF-R and to PBMC subsets, TNF-R were found to be expressed mostly by monocytes and in decreasing amounts and intensity in the following order: CD14+ cells > CD8+ cells > CD4+ cells. Expression of TNF-R was higher on cells obtained from HIV-infected than from noninfected subjects, and expression of p75 sTNF-R was much higher than that of p55 sTNF-R. Studying the U937 cells revealed that over 80% of the cells expressed both sTNF-R, but with greater fluorescence intensity in the HIV-1 chronically infected cells (U-937-IIIB). Treatment of the cells with PMA caused an accelerated release into the medium of both sTNF-R, with a sharp decline in their cell surface expression. Basal levels of mRNA transcripts for p75 TNF-R were higher in the U-937-IIIB cells than in the uninfected cells, but p55 TNF-R mRNA was expressed only in the HIV-1-infected cells. These findings show that HIV-1 infection is accompanied by predominant elevation of p75 TNF-R surface expression on monocytes and CD8+ lymphocytes, and results in both increased message and expression of these receptors in monocytes.(ABSTRACT TRUNCATED AT 250 WORDS)

An improved microculture-hemolytic spot assay for the study of carrier-specific antibody responses.

A microculture system based on limiting dilution and a hemolytic spot assay was adapted for study of the carrier-specific anti-hapten response in vitro. Spleen or lymph node cells from normal mice or mice immunized with NIP-ovalbumin (NIP-OVA) or NIP-human thyroglobulin (NIP-Tg) were cultured for 5 days by the microculture technique. The anti-hapten (anti-NIP) response was measured by assaying the supernatants of the microcultures in a hemolytic spot test with NIP coupled to sheep red blood cells. A micro-ELISA reader was adapted to read the degree of lysis in the spot assay which gives an objective quantitation of the degree of lysis and thus reduces the number of culture replicates. In vivo induced specific helper cells in mice immunized with the carrier protein, human thyroglobulin, as well as carrier-specific T cell factors, gave rise to carrier-specific anti-NIP responses. The microculture system may enhance the expression of T-cell helper function when suppressor cells or their precursors are present in the initial cell preparation.

Chemokines and chemokine receptors: role in HIV infection.

Our understanding of the host factors that determine susceptibility and progression of HIV infection has been very limited. In particular, it has been not clear why some people remain uninfected being repeatedly exposed to HIV-1, and others who have been infected by HIV, remain clinically asymptomatic for long periods of time. Recently it has been demonstrated that mutated forms of a number of chemokine receptors that act as coreceptors for HIV-1 entry may account for some of these phenomena. Furthermore, chemokines such as RANTES and others, being the natural ligands for chemokine receptors, have been shown to be effective inhibitors of HIV-1 infection. In this review we discuss some of the genetic, immunological, virological and epidemiological data relevant to the very important role chemokines and chemokine receptors play in HIV pathogenesis with special reference to the increased susceptibility of the African host to HIV infection.

Chlamydia trachomatis and HIV infection.

To study the interactions between Chlamydia trachomatis (CT) and human immunodeficiency virus (HIV) infections, we examined CT serologies in sequential serum samples of male homosexuals (MHS), followed over a mean period of 4 years. Of the MHS studied, 77 were HIV(-), 18 were HIV(+) and 10 patients seroconverted during the study period. Seventy matched heterosexual controls were tested concomitantly. CT-specific antibodies of both IgG and IgA isotypes were determined by an immunoperoxidase assay, indicating past and active infection respectively. Anti-CT IgG was frequently observed in both HIV(-) and HIV(+) MHS (40-50% vs. 23% of controls) and IgA antibodies were also common in both MHS groups (15-20% vs. 1.5% of controls). After HIV infection, no increase in CT antibodies occurred. We found serological data suggestive of active CT infection preceding seroconversion in 3 of 10 seroconverters vs. 5% of matched MHS controls who remained HIV(-) (P < 0.025), indicating a possible effect of CT infection on the acquisition of HIV should be further studied.

Antibodies to reverse transcriptase in HIV infection and progression to AIDS.

Serum antibodies to the reverse transcriptase (ART) of human immunodeficiency virus 1 (HIV-1) were sequentially determined by ELISA in a group of 41 HIV-seropositive male homosexuals and 101 matched healthy controls, over 1.5-6 years (mean follow-up 3.25 years). Mean ART levels were significantly higher in the patient group as compared to the controls (195 +/- 75 vs. 75 +/- 45 absorbance (A) units; P less than 0.05). When analyzed in parallel with clinical evaluation and T-cell subset determinations, a "surge" in ART activity was associated with a more favourable course: eleven patients whose ART profile showed an increase greater than 100 A units (mean delta A 159.6 units) showed an attenuated decrease of CD4+ (T helper) lymphocytes with a mean time of 42.5 months to reach a CD4+ number of 400 cells/mm3. In contrast, 25 matched seropositive patients whose ART remained constant became CD4+ less than 400 cells/mm3 within a mean time of 10.8 months (P less than 0.05). These results as well as individual patients' data support a surge in serum ART as a favourable prognostic indicator, and may indicate a protective role for this antibody which should be followed up and possibly utilized in the treatment or in the design of a vaccine against HIV-1.

Leukotrienes (LTC4, LTD4) confer glass non-adherence on leukocytes of asthmatic individuals. Dependency on cyclooxygenase products and calcium ion.

It has been suggested that cysteinyl-containing leukotrienes (LT) are important mediators in bronchial asthma. Since leukotrienes have been shown to mediate the leukocyte adherence inhibition (LAI) phenomenon observed in cancer-bearing host we have devised a modified LAI assay which determines the acquisition of non-adherence properties of leukocytes following a challenge with pure synthetic LT. Our results demonstrate that peripheral blood leukocytes of asthmatic individuals acquire non-adherence properties when challenged with pure synthetic leukotriene C4 and D4, a property not shared by peripheral blood leukocytes of control healthy individuals. Furthermore, we demonstrate that LT activity as manifested by the LAI assay is dependent on cyclooxygenase products, since 2 X 10(-6) M Indomethacin abrogated the LT-induced LAI and is restored by the addition of 2 X 10(-6) M prostaglandin E2 which is also synergistic to LT activity. Our results further suggest the possibility that leukotriene activity is dependent on calcium ions since it was negated by known calcium antagonists. It is thus suggested that the LT-induced LAI may serve as a tool for the study of the interrelationship between the metabolic pathways of arachidonic acid and calcium ion homeostasis.

Leukocyte adherence inhibition (LAI) for detecting specific tumor immunity in colorectal cancer.

Immunity to colorectal cancer antigen was tested by the tube leukocyte adherence inhibition (LAI) assay, using spent medium of human carcinoma cell lines as a source of antigen. The assay was positive in 18 out of 43 patients (41%) with colorectal tumor in comparison to only 2 out of 34 (5.8%) of colorectal cancer patients clinically free of disease, and to 4 out of 150 (2.6%) healthy subjects. The frequency of positive results correlated negatively with the tumor burden, 16 out of 29 (55.1%) patients with Dukes' A, B and C being positive compared to only 2 out of 14 (14.2%) patients with Dukes' stage D disease. Addition of PGE2 enhanced the sensitivity of the assay without affecting its specificity. The number of positive assays increased from 18 to 32 (41.8% to 74.4%) in the whole group of 43 colorectal cancer patients without altering significantly the frequency of positive results in the control group. The results with all groups of patients were influenced similarly by the addition of prostaglandins, the frequency of positive assays increasing from 55.1% to 82.7% and from 14.1% to 57.1% in early and advanced disease, respectively. These results lend further support to the value of the LAI assay in diagnosis and monitoring of the immune response in human colorectal cancer.

Allergen-specific leukocyte adherence inhibition (LAI) assay: sensitivity, specificity and mechanism.

An allergen-specific tube leukocyte adherence inhibition (LAI) assay has been developed in order to study the mechanism by which leukocytes lose their normal property of adherence to glass. Peripheral blood leukocytes (PBL) from 27 individuals allergic to Dermatophagoides farinae (DF), 10 with seasonal rhinitis not induced by DF and 49 non-allergic healthy volunteers were challenged in vitro with DF and a non-relevant allergen, Artemisia vulgaris (AV) and then assayed for the ability to adhere to glass tubes. Challenge by DF, but not by AV, resulted in loss of adherence by PBL from patients allergic to DF, but not in those of normal controls. The specific LAI response was dose-dependent and occurred only when a critical dose of 0.5 X 10(3) was employed. Following in vitro challenge with DF, radio-immunoassay using an antiserum to LTC4 detected immunoreactive material in supernatants of PBL from DF-allergic individuals. When highly enriched mononuclear cells from non-allergic individuals were armed with cytophilic allergen-specific IgE and challenged with the specific allergen, they lost the property of glass adherence and released a substance that was immunoreactive with LTC4. The results suggest that the chain of events leading to the LAI response in PBL from allergic individuals involves primary recognition of the allergen by specific IgE antibodies bound to receptors on mononuclear cells. The cells are thus triggered to synthesize cysteinyl-containing leukotrienes which mediate the LAI phenomenon. The results suggest that this assay may be used to study allergen-antibody interaction and the subsequent events leading to the clinical picture of atopic diseases.