Guy Delespesse

Characterization of Cellular Infiltrates in Skin Lesions of Atopic Eczema by Means of Monoclonal Antibodies

Frozen skin biopsies from 3 acute and 3 chronic lesions of atopic dermatitis were examined by means of various ortho-monoclonal antibodies (OKT3, 4] not equal to----4, OKT6, OKT8; OKIa and OKM1) in an indirect immunofluorescence technique. The results show that both T helper (T4) and T suppressor cytotoxic (T8) lymphocytes are present in the inflammatory infiltration which predominantly contained Ia mononuclear cells. Despite the absence of double staining procedure, the observations suggest that T4 cells predominate over T8 cells in the acute lesions whereas the reverse tendency is noted in the chronic lesions. T8 cells are found mainly in the superficial dermis or even in the epidermis; by contrast, T4 cells tend to be more deeply located in the dermis. The lesions are characterized by a dramatic increase in the number of Langerhans cells (OKT6, OKIa+) that are found not only in the epidermis but also in the dermis.

Enhancement of IgE synthesis and histamine release by T cell factors derived from atopic patients with bronchial asthma

Culture supernatants of unstimulated T cells (TCS) derived from normal donors or from atopic patients with bronchial asthma were tested for their ability to regulate the spontaneous IgE synthesis by B cells of normal and atopic subjects. The same TCS were also tested for their influence on the histamine release from leukocytes of house dust mites-sensitive patients. Addition of TCS to B cell cultures from allergic donors induced a dose-dependent increase of the spontaneous IgE production without affecting the synthesis of IgG, IgM, and IgA. The potentiating activity of TCS was observed only in B cell cultures spontaneously producing IgE; TCS were still active on irradiated B cells. The maximal IgE-enhancing activity was observed when TCS were added at the onset of B cell cultures. The supernatants of T cells lysed at day 0 did not contain IgE-potentiating factors. The antigen-induced but not the spontaneous histamine release from leukocytes of house dust mite-sensitive patients was enhanced by pretreatment with TCS from allergic donors. The enhancing activities of TCS on IgE synthesis and on histamine release could be removed by absorption with IgE-Sepharose and subsequently recovered by elution with glycine buffer. The results indicate that T cells of patients with asthma spontaneously release IgE-binding factors capable of increasing both the spontaneous IgE synthesis by B cells and the antigen-induced histamine release.

Suppressor T-lymphocytes in pregnancy.

ABSTRACT: Primiparous and multiparous healthy pregnant women were tested at the end of the gestation period, or immediately after delivery, for their lymphocyte reactivity to paternal or neonatal cells in mixed lymphocyte culture and in cell‐mediate cytotoxicity assays. Freshly isolated maternal lymphocytes had no spontaneous cytotoxic activity against PHA‐activated neonatal or paternal lymphocytes. In conventional 6‐day mixed lymphocyte cultures and in cytotoxicity assays, maternal lymphocytes displayed a response similar to that of paternal or third party lymphocytes when stimulated with neonatal, paternal, or third party lymphocytes. By contrast, in 3‐day mixed lymphocyte cultures maternal cells had a selectively lower response to paternal antigens (expressed either on cord blood cells or on paternal lymphocytes), than to unrelated alloantigens. Removal of T‐lymphocytes with IgG receptors (T), or of T‐lymphocytes reacting with OKT8 monoclonal antibody, corrected the depressed response of maternal cells in these 3‐day cultures. It is suggested that circulating maternal lymphocytes contain antigenspecific suppressor cells characterized by their membrane receptors for IgG and the T8 antigen.

Regulation of the Lymphocyte Response to Phytohemagglutinin During Pregnancy: Role of Adherent Cells and Prostaglandins

ABSTRACT: The lymphocyte response to optimal and suboptimal doses of phytohemagglutinin (PHA) has been investigated in 33 healthy pregnant women compared with 27 controls. Standard preparations of lymphocytes, isolated from the two groups of participants by Ficoll‐Metrizoate density gradient centrifugation, contained the same amount of peroxidase positive cells (± 10%) and exhibited the same response to PHA. Removal of cells adhering to plastic dishes (AC) led to an increased lymphocyte response in pregnant subjects but to a reduced response in the controls. Maternal lymphocytes depleted in AC had a significantly higher PHA response than did AC‐depleted lymphocytes from the control subjects. The apparent suppressor activity of AC on maternal lymphocytes is not mediated by prostaglandins as shown by the observations that indomethacin (10−6 M) had the same enhancing effect and prostaglandin E1 (10−6 to 10−8 M) the same inhibiting effect in the two groups of subjects. Collectively the data indicate that during pregnancy the cellular interactions involved in the lymphocyte response to PHA are altered; the data also explain some of the contradictory results in the literature.

Induction of IgA-specific suppressor activity in human T-lymphocyte cultures

Cell-free supernatants of human circulating T-lymphocyte cultures incubated with secretory IgA (S-IgA) specifically suppressed both spontaneous IgA synthesis by B lymphocytes isolated from allergic individuals and pokeweek mitogen-induced IgA secretion by peripheral blood mononuclear cells. Cell-free supernatants of T-cell cultures incubated with IgE had no effect on IgA, IgG, or IgM synthesis. Hence, it is concluded that upon incubation with S-IgA, but not with another Ig class, T lymphocytes release IgA-specific suppressor factors.

Direct action of cyclosporin A on human B-lymphocytes with regard to immunoglobulin production

Highly purified preparations of human B-lymphocytes were cultured with or without cyclosporin A (CyA; 1 microgram/ml) for 8 days with pokeweed mitogen (PWM) in the presence of helper factors or with Epstein-Barr virus (EBV). The amounts of IgG, IgM, IgA and IgE produced in cultures were measured by radioimmunoassays or by reverse hemolytic plaque-forming cell assays. The results demonstrate that whereas CyA had a strong suppressive effect on the production of immunoglobulins (Ig) by PWM-activated B-cells, it had an enhancing effect on EBV-activated B-cells. It is concluded that CyA has a direct effect on human B-lymphocytes and that it may suppress or enhance their activation depending on the stimulant employed to trigger the cells.

Demonstration of intracytoplasmic IgE in circulating lymphocytes of allergic individuals

Cells containing intracytoplasmic IgE (IC IgE) were demonstrated in the peripheral blood mononuclear cells of atopic individuals by means of indirect immunofluorescence, employing mouse monoclonal anti-human IgE antibody. IC IgE-positive cells are low-density B cells as shown by centrifugation on discontinuous bovine serum albumin density gradient and by their reactivity with B1 monoclonal antibody specific to B lymphocytes, respectively. Further characterization of these cells by means of a rosette assay employing anti-Ig-coupled bovine erythrocytes indicated that these cells were surface IgE (sIgE) positive and sIgM negative. The data strongly suggest that activated IgE B cells are circulating in the blood of allergic individuals.