In vivo modification of delayed type hypersensitivity by small molecular weight components derived from human leucocytes: partial purification of components causing amplification of response.

Human leucocyte dialysates contain components which, when injected intradermally in combination with an antigen to which the recipient displays prior sensitivity, produces an accelerated and intensified delayed hypersensitivity response. These components which we have termed leucocyte amplifiers, can be partially purified by gel filtration on Sephadex G-10 followed by high pressure reverse phase chromatography. The amplifiers do not produce an inflammatory reaction when injected intradermally by themselves. Amplifying effects were not observed when analogous sub-fractions prepared from erythrocytes or platelets were employed in the same manner. The leucocyte amplifiers were not able to transfer a new sensitivity to a non-sensitive recipient.