Control of Allergen-Induced Histamine Secretion by Human Basophils with F(ab) of Anti-IgE Antibodies.

A strategy was developed to obtain univalent F(ab) fragments against IgE, which would interfere with IgE-mediated activation of target cells, but lacked their activity due to cross-linking of IgE bound to Fc(epsilon)-receptors. Two kinds of mouse anti-human IgE monoclonal antibodies (mAb) against CH(2) or CH(3) domains induced histamine release from basophils of allergic patients and healthy donors. F(ab')(2) fragments of the mAb (0.

Histamine releasing activity of blood mononuclear cells is acquired by means of activation of mast cells.

It has been shown that peripheral blood mononuclear cells (PBMC) obtained from atopic patients with acute clinical manifestations of pollinosis, atopic dermatitis or bronchial asthma, and preincubated in vitro for 18 hours, acquired the ability to induce histamine release from auto-basophils and basophils of healthy donors. Both PBMC and their supernatants possessed this histamine releasing activity (HRA). During remission, HRA could be reproduced in sensitive patients after positive cutaneous tests with a specific allergen.

Mast cell regulatory effect on lymphoid cell proliferation.

It has been shown rat mast cells (MC) can modulate lymphocyte proliferation in vitro. Depending on concentrations tested both serosal MC and their supernatants enhanced the spontaneous and T-mitogen-induced proliferation of spleen and lymph node cells. In addition T-mitogen-induced thymocyte proliferation was also increased.