Histamine releasing factor is not an interferon

Abstract

The speculation that human histamine releasing factor (HRF) — a lymphokine that releases histamine from human tissues [1, 2], might be the same as γ-interferon was investigated. The speculation arose from the fact that HRF and γ-interferon are both lymphokines and have both been reported to affect histamine release from human basophils [1, 2, 3, 4]. Using purified γ-interferons either naturally obtained or E. Coli-derived (recombinant DNA technique), as well as α-, α-2 arg, and β-interferons, it was found that: 1. Unlike HRF, the interferons neither induced histamine release nor affected antigen-induced histamine release from human basophilsin vitro. 2. HRF is partially acid-stable whereas γ-interferon is acid labile. 3. HRF samples had little interferon activity which did not correlate with HRF activity. 4. The estimated molecular weight of HRF is 12,000–18,000 daltons and contrasts to those of interferons, which exceed 30,000 daltons. The results strongly suggest that HRF is very unlikely to be a γ-interferon or indeed any other class of interferon.