Fc receptors for IgE (Fc epsilon R) on human lymphoid cells: inducible expression of Fc epsilon RII (CD23) on lymphocytes and detection by monoclonal anti-Fc epsilon RII antibody

[Basophilic granulocytes and autoimmune diseases. Can basophilic granulocytes modulate B-cell functions in systemic lupus erythematosus?]

BACKGROUND

B-cells play an important role in the pathogenesis of systemic lupus erythematosus (SLE); however, many other cell types are also involved in disease development. In a murine lupus model it was demonstrated that basophils are indispensable for the development of lupus symptoms.

AIM

This study investigated whether there is evidence for a relevant interaction between B-cells and basophils under physiological and pathological conditions.

MATERIAL AND METHODS

A selective review of the literature was performed and some preliminary data about the interaction of basophils and B-cells are reported in this article. For the experiments, isolated B-cells were cultured in vitro in the presence or absence of basophils and B-cell survival, proliferation, plasma cell development and antibody production were determined.

RESULTS

Data from the literature show that there is evidence for an interaction between basophils and B-cells in a murine model. Our investigations confirmed that human basophils also support the survival and proliferation of B-cells. Furthermore, plasma cell differentiation and antibody production, most importantly IgG secretion, are enhanced. First experimental ex vivo analyses of basophils from SLE patients demonstrate that these cells exhibit a higher activation level compared to basophils from healthy controls.

DISCUSSION

In summary, previously published data and our own data demonstrate that there is an interaction between human basophils and B-cells. A better understanding of the role of basophils in the pathogenesis of SLE could lead to the development of new therapeutic strategies.

The effect of H1 receptor antagonists on peripheral blood mononuclear cells, adenoid cells and primary cell lines

This study describes the in vitro effect of three H1 receptor antagonists (dexchlorpheniramine, terfenadine and loratadine) on human peripheral blood mononuclear cells (PBMC, n = 30) from allergic patients and healthy individuals. The three H1 receptor antagonists significantly inhibited antigen/mitogen-induced PBMC proliferation in a concentration-dependent manner. Allergen-specific T-cell responses in allergic individuals were similarly inhibited. The effect of the three drugs was also tested in cultures of mononuclear cells derived from adenoid tissue. The growth kinetics were investigated using spontaneously proliferating cell lines to examine whether the inhibition was caused by general toxicity. Three cell lines, HCT 8 (an ileocaecal adenocarcinoma) RPMI 8866 (B-cell line) and 166 A2 (T hybridoma) were tested. Loratadine (< 0.03 microM) and dexchlorpheniramine (< 0.62 microM) altered the kinetics of HCT 8 and RPMI 8866, respectively. When testing RPMI 8866 and 166 A2, the growth-inhibitory effect of terfenadine and loratadine could be neutralized by addition of cell culture filtrate from RPMI 8866 or 166 A2. These culture filtrates are rich in soluble low-affinity IgE receptor (sCD23) and IgE-binding factor (IgEBF), respectively. Our findings show that the antihistamines investigated display some non-convential in vitro anti-allergic properties possibly not related to their interaction with the H1 receptor. In addition, our results suggest: a) The H1 receptor antagonists used differ in their pattern of cell inhibition; b) The inhibitory effect is completely reversible at low drug concentrations.

The effect of disodium cromoglycate on in vitro proliferation of peripheral blood mononuclear cells from allergic and healthy donors

The effect of disodium cromoglycate on in vitro proliferative responses of peripheral blood mononuclear cells from healthy individuals, allergic patients with moderate serum IgE and patients with atopic dermatitis and high levels of serum IgE was investigated. Peripheral blood mononuclear cells were stimulated with mitogens (phytohaemagglutinin, Concanavalin A), recombinant interleukin-2, calcium ionophore + phorbol 12-myristate 13-acetate, purified protein derivative of tuberculin and allergens. It was possible to induce in vitro specific, allergen-triggered responses only in allergic individuals with moderate serum IgE and not in individuals with atopic dermatitis and high serum IgE. Generally, whenever the stimulatory signal(s) caused a significant proliferative response, disodium cromoglycate inhibited the proliferation. This inhibition was seen for all activation agents and for both healthy and allergic individuals. By contrast, for certain non- or low-responders (both healthy and allergic individuals) disodium cromoglycate seemed to amplify the proliferation to various activation signals. Only non- or low-responder cells derived from atopic dermatitis patients showed a biphasic kinetic response pattern when stimulated with the drug in combination with recombinant interleukin-2, recombinant interleukin-2 + ionophore or specific allergens.