Low MW B-cell growth factor potentiates histamine release from human basophil leucocytes

The aim of the present study was to evaluate the effects of a commercial preparation of low molecular weight (MW) B-cell growth factor (BCGF), a product of activated human T cells, on histamine release from stimulated human basophils. In all the 23 cases tested, BCGF enhanced significantly the histamine release from stimulated human basophil leucocytes. After leucocyte incubation with 1% v/v BCGF, anti-IgE-induced histamine release increased from 11.9 +/- 1.9% to 31.8 +/- 3.3% (mean +/- SEM; P less than 0.001), formyl-methionine peptide-induced histamine release increased from 24.9 +/- 3.9% to 50.3 +/- 5.3% (P less than 0.001) and complement-mediated (i.e. induced by zymosan-activated human serum) histamine release increased from 10.7 +/- 1.8% to 29.2 +/- 5.2% (P less than 0.001). The enhancing effect of BCGF on histamine release was related to dose, temperature and time, since it was optimal after incubation with 10% v/v BCGF at 37 degrees for 60 min. BCGF activity persisted when the cells were washed after incubation and could also be observed when leucocyte incubation was carried out in the absence of extracellular Ca2+. It is noteworthy that basophils which showed a low response to activating agents released significant amounts of histamine after incubation with BCGF. These observations support the hypothesis that lymphocytes and lymphocyte-derived products may play a role in triggering and maintaining allergic reactions.