from Clostrldium perfringens [type VI, 1-3 U/rag (NAN-lactose substrate), Sigma Chemical Co., St. Louis, Mo.] at 37°C for 45 rain. 25.106 lymphocytes in 1 ml of Tris-buffered Hanks'

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Serum samples from a cohort of patients with chronic hepatitis C virus (HCV) infection were assayed for IgM anti-HCV/core reactivity with a "site-specific" ELISA, in which the solid phase was charged with the synthetic polypeptide analogue corresponding to the first 75 amino acids of the HCV core antigen (sp75). Thirteen of 24 (54%) patients exhibited IgM anti-sp75 reactivity. Both high-titered (1/16,000-1/32,000) and low-titered (1/1,000-1/4,000) IgM anti-sp75 reactive sera were found. IgM anti-sp75 antibodies persisted in the circulation over a long period in patients with fluctuating abnormal ALT levels. There was a striking association between detection of specific IgM anti-sp75 reactivity and the presence of HCV RNA in serum. Thus 11 of 15 (73%) sera containing HCV RNA also contained IgM anti-sp75 antibodies, while none of the HCV RNA-negative sera were IgM anti-sp75 reactive. Five of 11 patients without detectable levels of specific IgM anti-sp75 antibodies had their ALT levels returned to normal within 8 months to 3 years. Furthermore, a significant correlation was noted between the specific IgM anti-sp75 titers and the concentration of total plasma IgM, indicating that the immunological active region sp75 within the capsid of HCV has the capacity to induce an IgM secretion, which constitutes a substantial portion of the total plasma IgM, in patients with chronic HCV infection.(ABSTRACT TRUNCATED AT 250 WORDS)

The mode of interaction of twelve lectins with human T lymphocytes was investigated. In order to establish possible differences between mitogenic and nonmitogenic lectins, they were studied for their capacity to induce or inhibit DNA synthesis. Their interaction with intact T cells was studied by immunofluorescence and "Cr release. Further, lectins conjugated to Sepharose were investigated with regard to their capacity to bind surface glycopeptides from T cell lysates. Operationally, the lectins could be divided into three groups: (a) mitogenic lectins; (b) lectins inhibitory for lymphocyte mitogenesis as induced by leucoagglutinin (La) from Phaseolus vulgaris; and (c) nonmitogenic lectins which were noninhibitory in this La system. Six lectins were nonmitogenic. For two or possibly three of these, lack of mitogenicity was due to complete or partial failure to bind to the lymphocytes. This explanation could not account for lack of mitogenicity of the other three nonmitogenic lectins. Only two of the lectins utilized inhibited La-induced mitogenesis. However, when the lectins were compared with regard to their capacity to bind surface glycopeptides from T cell lysates, important differences between mitogenic and nonmitogenic lectins were seen. As revealed by polyacrylamide gel electrophoresis in sodium dodecyl sulfate and autoradiography, the mitogenic lectins bound a larger number of surface glycopeptides (15-20) than the nonmitogenic lectins (3-10). More importantly, five distinct glycopeptides (gp 135 K, 125 K, 105 K, 95 K and 43 K) were bound by all mitogenic lectins but not by the nonmitogenic lectins. It remains to be established whether these glycopeptides are present on the T cells which are susceptible to the mitogenic action of the lectins and whether it is the interaction of the lectins with one or several of them which triggers mitogenicity.