Differences in response to anti-IgE and to anti-IgG in basophils from patients with bronchial asthma

New flow cytometric method for surface phenotyping basophils from peripheral blood

To clarify the role of basophils in the pathogenesis of allergic disease, we developed a new method for performing surface phenotyping of these cells in centrifugation-enriched mononuclear cell fraction. This method identified basophils on the basic of a negative reactivity with mixed FITC-conjugated monoclonal anti-bodies (mAbs) (anti-CD2, -CD14, -CD16, and -CD19) with analysis performed by flow cytometry. The validity of this approach was confirmed by sorting experiments. Various PE-conjugated mAbs were also used to examine binding to FITC-negative basophils. Basophils from asthmatic patients (n = 14) as well as from normal subjects (n = 6) were shown to express CDw32 (Fc gamma RII), CD25 (IL-2R), but not CD64 (Fc gamma RI). We also detected binding of IgG1 and IgG4 to basophils. This method of phenotyping was very rapid and simple. It thus appears to be useful in the study of allergic disease, as well as of the biology of the basophil.

Basophil immunoglobulin receptors in asthmatics under immunoscanning electron microscopy

Immunolatex particles were used as markers for IgE receptors on basophils using electron-microscope scanning. These particles appeared to bind specifically to basophils. Basophils from atopic asthma patients showed greater binding to latex particles than those from intractable asthma patients or healthy subjects. Cap and patch formations on IgE receptors were frequently found in basophils of atopic asthmatics, and cap formation was observed only on basophils that were pear-shaped. The redistribution of IgE receptors, such as that by cap formation, may be a significant triggering mechanism for basophil activation. The latex density on basophils pre-treated with anti-human IgG was much greater in intractable asthmatics than in atopic asthmatics or healthy subjects, and almost all basophils with increased immunolatex particles were pear-shaped, suggesting the presence of some IgG receptors on the surface, and such receptors may play an important role in intractable asthma.

Decrease in reactivity of basophils by immunotherapy with housedust extract

Changes of basophil reactivity to housedust extract and anti-IgE during immunotherapy was examined in thirteen patients with bronchial asthma sensitive to housedust. (i) A significant decrease in the morphological reactivity of basophils to housedust extract was observed 6 months after the beginning of immunotherapy with the antigen, and a significant decrease after 12 and 18 months' therapy, accompanied with the decrease of histamine release from the cells. The percent reactive basophils to the antigen decreased from 59.2 +/- 2.9% before the therapy to 40.0 +/- 1.8% after 18 months' immunotherapy. (ii) A decrease in the morphological reactivity of basophils to anti-IgE was also shown during immunotherapy. The basophil reactivity to anti-IgE decreased significantly at the late stage (18 months) of immunotherapy. (iii) A significant reduction of specific IgE antibody to housedust was observed 12 and 18 months after the beginning of immunotherapy. It was suggested from these results that immunotherapy causes some changes on the surface of basophils and decreased reactivity of the cells, and that a decrease of reactive basophils to anti-IgE in the process of immunotherapy might be due to a decrease in number of IgE receptors essentially or functionally.