Further studies on the suppression of delayed hypersensitivity reactions in the rat and guinea-pig by antibody against lymph node extracts.

Sera of rabbits immunized with rat or guinea-pig lymph node cell extract were fractionated by column chromatography. In all cases the fractions which contained antibody were able to suppress the inflammatory response of delayed hypersensitivity reactions, whereas fractions devoid of antibody had no activity. Furthermore, rabbit antiserum to guinea-pig serum, or its fraction rich in antibody, were unable to suppress delayed hypersensitivity reactions, indicating that antibodies to the serum proteins present in the cell extract were not responsible for the anti-inflammatory activity of the anti-cell extract serum, in spite of the close association of LNPF activity with plasma protein in the lymph node extract. Haemagglutination inhibition experiments detected in the anti-cell extract antisera a small titre of specifc antibody which may be responsible for the inflammatory suppression.