Histamine release from human leukocytes: modulation by a cytochalasin B-sensitive barrier

Area of Science:

• Immunology
• Cell Biology
• Pharmacology

Background:

• Human leukocytes release histamine in response to stimuli like antigen E or anti-IgE.
• This histamine release involves multiple stages, including antigen-dependent and antigen-independent phases.
• Cytochalasin B is a fungal metabolite with known effects on cellular processes.

Purpose of the Study:

• To investigate the effect of Cytochalasin B on human leukocyte histamine release.
• To elucidate the mechanism by which Cytochalasin B enhances histamine release.
• To determine if this effect is related to the antigen-independent stage and cyclic AMP modulation.

Main Methods:

• Human leukocytes were treated with Cytochalasin B.
• Leukocyte sensitivity to antigen E or anti-IgE-mediated histamine release was measured.
• The stage of histamine release affected by Cytochalasin B was analyzed.
• The interplay between Cytochalasin B, a cytochalasin-sensitive barrier (CSB), and cyclic adenosine monophosphate (cAMP) was examined.

Main Results:

• Cytochalasin B enhanced leukocyte sensitivity and reactivity to histamine release by up to 10-fold.
• The effect of Cytochalasin B was localized to the second, antigen-independent stage of histamine release.
• A cytochalasin-sensitive barrier (CSB) was identified as a modulator of antigen-triggered histamine release.
• The CSB modulation was found to be separable from the effects of cyclic adenosine monophosphate (cAMP).

Conclusions:

• Cytochalasin B potentiates antigen- and anti-IgE-induced histamine release from human leukocytes.
• A cytochalasin-sensitive barrier regulates histamine release, particularly in the antigen-independent phase.
• This regulatory mechanism is distinct from modulation by cyclic AMP, offering new insights into leukocyte activation.