Rapid and constant detection of HIV antibody response in saliva of HIV-infected patients; selective distribution of anti-HIV activity in the IgG isotype.

Anti-HIV antibodies can be specifically detected with a sensitivity and a specificity of 100% in the saliva of all HIV-infected patients. A saliva collection device facilitates the sampling procedure, and if a rapid test is used, the diagnosis of infection can be established in as little as 10 min. The analysis of a group of CDC stage IV AIDS patients showed a decrease in lactoferrin (produced by the oral mucosa) in comparison with HIV-negative controls, associated with an increase in albumin (filtering from plasma), indicating an alteration of the mucosal barrier. The salivary anti-HIV-gp160 activity was largely carried by the IgG isotype whereas the salivary antibacterial activity (anti-Streptococcus sobrinus; anti-LPS from Escherichia coli) remained located in the IgA isotype as usually observed with all infectious agents. Salivary IgG carried a specific anti-gp160 activity 25-fold higher than that of serum IgG. Thus, significant local synthesis of specific IgG by oral mucosa was revealed as a characteristic of HIV infection.

Activation and infection of B cells by Epstein-Barr virus. Role of calcium mobilization and of protein kinase C translocation.

Both the activation and the transformation of human B cells by EBV were inhibited by either the Ca2+ channel blocking agent verapamil or the combination of theophylline and dibutyryl cAMP: the day 4 and day 20 peaks of [3H]TdR incorporation were abolished; the EBNA marker was not expressed by day 10; lymphoblastoid cell lines did not arise. Short term incubation of B cells with EBV or verapamil showed that the effect of verapamil was reversible and took place early in the interaction between EBV and B cells. The effect of EBV on the early metabolic events of B cell response was thus examined in the presence and in the absence of the drugs. Compared to anti-mu stimulation, supernatant of the transforming B95-8 strain as well as that of the non-transforming P3HR1 strain induced a drug sensitive increase of the free cytosolic Ca2+ concentration. This increase was associated with a protein kinase C translocation from the cytosol to a membrane bound compartment. Moreover, B95-8 supernatant induced phosphatidyl inositol metabolism by human B cells but at least four times less than that induced by anti-mu antibody. These metabolic events induced by EBV were significantly inhibited by anti-CD21 antibodies whereas anti-mu induced metabolic events were not. The infection of EBV negative Ramos cell line was prevented by verapamil or by theophylline + dibutyryl cAMP. Verapamil did not modify the density of EBV receptors but negatively interfered with the penetration of the virus into B cells. Thus B cell activation through the EBV receptor and virus penetration share a common metabolic pathway which is also used for transduction of the signal delivered through the membrane Ig.

Antigen-induced and polyclonal B-cell responses in human peripheral blood lymphocyte cultures.

This work was designed to delineate the anti-hapten antibody (Ab) response induced by trinitrophenol-polyacrylamide (TNP-PAA) beads from the nonspecific B-cell response which concomitantly occurs in human peripheral blood mononuclear cell (PBMC) cultures. Indeed human PBMC produce consistent amounts of immunoglobulins when cultured at high cell density in the presence of fetal bovine serum, regardless of the presence of antigen. In contrast, the stimulation of such cultures by TNP-PAA leads to an Ab response characterized by the following: cells secreting anti-hapten Ab at a high rate (detected by a plaque-forming cel (PFC) assay); a 10-30 times enhancement in the number of hapten-specific binding cells (detected by a rosette-forming cell (RFC) assay); the production of anti-TNP IgM Ab (detected by an ELISA assay). The anti-TNP response is specifically triggered by the particulate antigen, as shown by the following: The TNP-PAA antigen induces a clear-cut increase in the amount of anti-TNP Ab whereas it only marginally increases that of total IgM. The anti-TNP Ab response is specifically abolished when anti-TNP RFC are depleted from the PBMC preparation before the initiation of the cultures. The anti-TNP Ab response is specifically abolished when PBMC are triggered by TNP-PAA in the concomitant presence of a soluble TNP-protein conjugate. These results demonstrate the ability of polymeric antigens to specifically activate human peripheral blood B cells.

Human B cell activation: selective sensitivity of the early stages to calcium channel-blocking drugs.

The importance of Ca2+ in the early events of lymphocyte activation has been suggested by several studies. We examined the effect of calcium channel-blocking drugs (verapamil and nitrendipine) on the progression of human B cells through their activation cycle. Our results show that these drugs suppress the anti-mu-induced human B cell proliferation and interfere with the early events of the B cell activation in a dose-dependent fashion. This suppression correlates with a marked decrease in anti-mu-induced 45Ca2+ uptake. Calcium channel-blocking drugs inhibit the anti-mu-induced uridine incorporation and the appearance of the activation marker defined by the 4F2 monoclonal antibody. Calcium channel-blocking drugs also inhibit B cell proliferation induced by the costimulation with anti-mu antibody and B cell growth factor (BCGF). However, this inhibition takes place at the early (anti-mu-dependent) stage of B cell activation: the BCGF-dependent proliferation of in vitro anti-mu-activated B cells is only marginally inhibited. Finally the proliferation of Epstein-Barr virus-infected B cell lines is resistant to the effect of calcium channel-blocking drugs.

Detection of human Fc (gamma) receptors on streptococci by indirect immunofluorescence staining: a survey of streptococci freshly isolated from patients.

With immunofluorescence staining, Fc (gamma) receptors were found on groups A, C, and G streptococci and never on pneumococci or on groups B, D, H, or K streptococci.