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When human polymorphonuclear basophils, a type of white blood cell with antibodies of the immunoglobulin E (IgE) type on its surface, are exposed to anti-IgE antibodies, they release histamine from their intracellular granules and change their staining properties. The latter can be demonstrated at dilutions of anti-IgE that range from 1 x 10(2) to 1 x 10(120); over that range, there are successive peaks of degranulation from 40 to 60% of the basophils, despite the calculated absence of any anti-IgE molecules at the highest dilutions. Since dilutions need to be accompanied by vigorous shaking for the effects to be observed, transmission of the biological information could be related to the molecular organization of water.

PLATELET-activating factor (PAF) is a newly described mediator of anaphylaxis which has been implicated in the deposition of immune complexes in acute serum sickness in rabbits1–4. It is released by leukocytes and tissues, most probably by the basophils or mastocytes from various mammalian species, under the influence of various substances known to activate these cells5,6. The study of the chemical nature of the compound responsible for the PAF activity led us to the preparation of large amounts of PAF from hog leukocytes5. Several fractionation steps of the crude material yielded a highly active chloroform-soluble fraction. We usually started these procedures with 1001 of hog blood which yielded 1001 of PAF, the biological activity of which could be detected at the 1-μ1 level. Nevertheless, we have not yet obtained sufficient homogeneous material to apply the current methods for structural analysis (mass spectrometry, magnetic nuclear resonance, hydrolysis reactions and so on). We therefore used different lipases to get some insight into the structure of PAF. We present here the results of these experiments which suggest that PAF is a 1-lyso-glycerophospholipid.