A procedure has been developed to yield infectious elementary bodies of the lymphogranuloma venereum strains LGV 434 and 404 of Chlamydia trachomatis, labelled during intracellular growth in HeLa 229 cells. The final preparation, obtained after velocity sedimentation of a polycarbonate membrane-filtered sample through a sucrose gradient, is free of host proteins and, more importantly, of chlamydia1 reticulate bodies. Using such purified preparations, it was found that the association of LGV 434 elementary bodies with HeLa 229 cultures was unaffected by the pretreatment of the host cells with a variety of lectins or with neuraminidases from Clostridium perfringens and Vibrio cholerae. The association was inhibited by dextran sulphate and by mild trypsin treatment of HeLa cultures. Treatment of purified elementary bodies with trypsin, chymotrypsin, neuraminidases and a variety of carbohydrates and lectins did not produce any change in the rate of association with HeLa cultures. Heat-inactivated elementary bodies were significantly less able to associate with the host cells.

Using highly purified elementary bodies of Chlamydia trachomatis UW-31 (serotype K), we found that HeLa 229 monolayer cultures bound more 32P-labeled chlamydiae after pretreatment with the lectin wheat germ agglutinin. The lectin, on the other hand, inhibited competitively when chlamydial association was assayed in the presence of polycations. The two effects of wheat germ agglutinin were abolished when N-acetylneuraminic acid (NeuNAc)or N-acetylglucosamine (GlcNAc)-preincubated wheat germ agglutinin was used. Brief exposure of HeLa cells to neuraminidase abolished the ability to bind the elementary bodies, whether or not polycations were present. Furthermore, at 5°C but not at 37°C, NeuNAc, GlcNAc and N-acetylgalactosamine inhibited chlamydial association only in the absence of the polycation DEAE-dextran. The results suggest that NeuNAc residues on the plasma membrane are the principal, but not the only, receptors for this strain of C. trachomatis.

HLA class I antigen expression on peripheral blood mononuclear cells was evaluated by flow cytometry in 21 HBeAg-positive patients with chronic hepatitis B. Measurements were made before, during or after treatment with recombinant interferon-alpha-2b, either given alone or after a 6 wk course of prednisone. Immunohistochemical staining for human leukocyte class I antigen was also evaluated in 28 percutaneous liver biopsy specimens either obtained before or after therapy (N = 27) and during therapy in one instance. The amount of HLA class I antigen on peripheral blood mononuclear cells varied markedly among individual patients, but the overall results indicated that the level of inducible antigen did not correlate with increments of ALT during therapy or with a virological response to therapy. Hepatocyte staining for HLA class I antigen was observed in a minority of biopsy specimens (29%) and also did not appear to predict a response or correlate with the severity of histological disease. These data do not support current theories concerning pathogenetic mechanisms in chronic hepatitis B nor do they suggest that spontaneous display of HLA class I antigen on hepatocytes or interferon-induced expression of these antigens on peripheral blood mononuclear cells is a critical determinant for a response to therapy.

The density of HLA Class I antigen on peripheral blood mononuclear cells was evaluated by flow cytometry in the following groups of patients: 41 HBsAg carriers; 12 individuals with chronic non-A, non-B hepatitis, and 4 with acute hepatitis B. Fourteen of the carriers were positive for antibody to human immunodeficiency virus, and all were negative for antibody to delta agent. Elevated levels of Class I antigen were observed in only 19% of patients with chronic hepatitis B virus infection alone. In contrast, 86% of HBsAg carriers with coexistent human immunodeficiency virus infection demonstrated increased expression. These data suggest that HBsAg carriers are capable of sustaining a systemic interferon response to another chronic viral infection and further supports the hypothesis that a defective interferon response exists in chronic hepatitis B virus infection.