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 <0.001), formyl-methionine peptide-induced histamine release increased from 24.9 ± 3.9% to 50.3 ± 5.3% (P <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 <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° 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.