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Human ultrafiltrated leukocyte extracts (MW less than 5000) were fractionated by Sephadex G-10 column chromatography and the effects of these fractions on leukocyte random locomotion were investigated in vitro. Fr-4, one of these fractions, had significant leukocyte random locomotion inhibitory activity, independent of the presence of mononuclear leukocytes. This inhibitory activity was not due to cytotoxic effects on leukocytes. As seen by scanning electron microscopy, the number of cell surface pseudopods on leukocytes incubated with Fr-4 was reduced. Fr-4A, one of three fractions separated from Fr-4 by Sephadex G-25 column chromatography, significantly inhibited leukocyte random locomotion. Fr-4A contained numerous components, one of which was identified as 2-deoxyribose, on the basis of thin-layer chromatography. Biologically 2-deoxyribose showed an inhibitory effect on leukocyte locomotion and a reduction of the extrusion of pseudopods on the surface of leukocytes, at the range of assayed concentrations. This inhibitory activity is probably derived from 2-deoxyribose.

An inhibitory factor on lymphocyte migration was detected using a capillary random migration assay in the culture supernatant of peritoneal exudate macrophages cultured at concentrations greater than 8 x 10(6) cells/ml. After examining different macrophage-like cell lines, J774A.1 cells were found to produce this inhibitory factor, which was termed lymphocyte migration inhibitory factor (LMIF). The inhibitory effect of LMIF on the migration of spleen lymphocytes, thymocytes, and bone marrow cells was determined. The migration of thymocytes was more sensitive to LMIF than was the migration of spleen lymphocytes and bone marrow cells. Interestingly, when the effect of LMIF was tested on the migration of spleen T cells and B cells, T cells were more sensitive than B cells. When the thymocytes were separated by peanut agglutinin into mature and immature thymocytes, the migration of mature thymocytes was more sensitive than that of immature thymocytes, the migration of mature thymocytes was more sensitive than that of immature thymocytes to the effect of LMIF, suggesting that the greatest effect of LMIF was on the migration of mature T cells. Partial purification of LMIF by ion-exchange and gel-filtration chromatography revealed that it is approximately 14,000 in molecular weight and could exist in either monomeric or dimeric forms. The possible role of this factor in an immune response is discussed.

This investigation examines the immunologic basis for specific antigen-induced tube leukocyte adherence inhibition (LAI) reactivity of draining lymph node cells (LNC) from dogs with canine transmissible venereal sarcoma (CTVS). CTVS regressor LNC, macrophage-depleted LNC, and enriched T lymphocyte fractions, but not enriched B lymphocyte fractions, were specifically reactive to CTVS antigen extract in direct tube LAI. In addition, regressor LNC amplified tube LAI responses by generating supernatants with leukocyte adherence inhibition factor (LAIF) activity for normal dog indicator LNC and enriched peripheral blood mononuclear cells (PBMC) in an indirect tube LAI assay. However, macrophage-depleted LNC and enriched T lymphocyte fractions failed to generate supernatants with LAIF activity, suggesting that macrophage accessory cells play a central role in the amplification of tube LAI. Interestingly, CTVS regressor peripheral blood leukocytes (PBL) and PBMC, which were specifically reactive in direct tube LAI, also failed to generate supernatants with LAIF activity. These findings demonstrate a distinction between LAIF-mediated amplification and direct tube LAI reactivity, and suggest that leukocyte populations with differing cellular proportions and from different immunologic compartments may participate in tube LAI via different mechanisms.

Thymic (T) or bursal (B) lymphocytes from chicks sensitized to Mycobacterium tuberculosis produce an avian lymphocyte inhibitory factor (LyIF). The physiochemical properties of both T and B LyIF were established by ultrafiltration which yielded four fractions with molecular weight ranges of greater than 100,000; 50,000-100,000; 10,000-50,000; and less than 10,000; enzymatic treatment with chymotrypsin and neuraminidase; varying pH; and heat exposure. These studies demonstrated that the maximum activity for both T and B LyIF was within a molecular weight range of 10,000-50,000. Both were sensitive to chymotrypsin and neuraminidase treatment. Both were stable at 56 degrees C for 30 min and resistant to changes in pH from 5 to 9. T-Cell migration was inhibited equally by B or T LyIF, while B-cell migration was inhibited to a lesser extent by T LyIF and B LyIF. Further experiments should establish the reasons for these observed differences in cross-reactivity.