Se-Kyung Oh

Identification of HIV-1 Envelope Glycoprotein in the Serum of AIDS and ARC Patients

Binding of the human immunodeficiency virus type 1 (HIV-1) external envelope glycoprotein (gp120) has been reported to alter the function and surface antigen expression of lymphocytes and monocytes in vitro. To determine whether these in vitro findings could be relevant in vivo, we searched for the presence of this antigen in the serum of patients with AIDS and the AIDS-related complex (ARC). Using an antigen capture enzyme-linked immunosorbent assay (ELISA) with polyclonal anti-gp120 antibody, we detected envelope antigens (gp160/120) in serum of 22 of 32 AIDS patients. In contrast, an ELISA using solid-phase recombinant CD4 to capture gp160/120 failed to detect any positives. A modification of the anti-gp120-based ELISA identified gp160/120-IgG immune complexes in all of 11 AIDS patients tested and in 4 ARC patients who were negative for gp160/120 antigen. We conclude that gp160/120, predominantly in the form of immune complexes, can be identified as circulating antigen in patients with AIDS. The potential pathogenic consequences of this antigenemia, its relation to soluble CD4 therapy, and its application as a clinical marker of disease merit further study.

Quantification of Soluble E‐Receptor in the Serum of Patients with Various Diseases and Its Accompanying in Vitro Immunosuppression in Neoplasia

Evidence in the literature indicates that soluble E‐receptor in the serum may modulate T‐dependent immune response. We have developed a solid‐phase radioimmunoassay to measure the soluble form of E‐receptor from various sources. The assay detects solubilized antigens derived from E‐receptor‐bearing T lymphocytes and not with non‐E‐receptor‐bearing B lymphocytes. The sensitivity limit of the assay is 0.1 ng/ml of purified E‐receptor antigen. Using this assay, one can show that the T‐cell mitogen phytohaemagglutinin stimulated both lymphocytes and cells of the resting human T‐cell lymphoma cell line Jurkat to shed or secrete E‐receptor into the culture medium. Results of the radioimmunoassay performed on human sera indicated that some patients with Hodgkins disease, melanoma, sarcoma, or acute or chronic lymphocytic leukaemia had elevated levels of this antigen in their serum, whereas normal human sera registered lower levels, Elevated levels of the soluble form of E‐receptor in the serum were suggestive of an in vitro assessment of their immunosuppressive activity. These results indicate that activation of T‐cell immunity in vivo may result in humoral immunosuppression.

Tumor regression and temporary restoration of immune response after plasmapheresis in a patient with recurrent oral cancer.

A major response to plasmapheresis is reported in a patient with advanced, recurrent squamous cell cancer of the oral cavity, similar to that previously reported in three of six comparable patients. Tumor regression followed temporary reduction of inhibition of normal lymphocyte response to phytohemagglutinin (PHA) by the patients serum (from 99% to zero) and partial restoration of the patients lymphocyte response (from 2% to 38% of control). The IgE level rose both overall and during some exchanges; this correlate of tumor response had been noted earlier. The tumor showed extensive necrosis, but the clinical effects were relatively short‐lived and the patient died 11 weeks later. Biopsy specimens taken early in apheresis showed intense new infiltration of tumor by lymphocytes and monocytes; later biopsy specimens showed predominantly plasma cells with trapping and lysis of tumor cells. No other anti‐cancer therapies had been used for 16 months before this trial, and no replacements were given other than saline and albumin.

Modulation of E-receptor expression on activated T lymphocytes

Our study indicated that the newly synthesized E-receptor, as measured with 125I-labeled monoclonal anti-E receptor antibody, on activated T lymphocytes were responsible for forming stable E-rosettes at 37 degrees C. Maximum induction of new E-receptor expression required at least 50 hr of culture with polyclonal T-cell activators, phytohemagglutinin, or phorbol myristate acetate. Polyclonal B-cell activator, lipopolysaccharide were not able to induce new E-receptor expression on the surface of T lymphocytes. The expression of the new E-receptor paralleled with the induction of Tac antigen expression. Interleukins 1 and 2 or Interferon-gamma were not able to initiate the induction of new E-receptors. However, a neuropeptide, endorphin exhibited biphasic effect on modulating the E-receptor expression, in the absence of polyclonal activators. As is the case with Tac antigen expression, induction of new E-receptor antigen may be a marker for activated T lymphocytes.

Quantitation of serum suppressor factor, related to the erythrocyte receptor of human peripheral blood T lymphocytes as measured by radioimmunoassay☆

A solid phase radioimmunoassay for a serum suppressor factor has been developed. The factor was previously purified from malignant ascites fluids and shown to be related to the sheep erythrocyte receptor of human peripheral blood T lymphocytes. This humoral suppressor factor has been termed suppressive E-receptor factor. Using this assay, it was demonstrated that both ascites fluids and sera derived from patients with solid tumors contain elevated levels of this factor compared to similar specimens from patients with a variety of nonmalignant diseases. The concentration of this SER factor does not correlate with serum immunoglobulin G levels but it does correlate with the ability of sera from individual patients to inhibit phytohemagglutinin-induced DNA synthesis by normal human peripheral blood T lymphocytes. Kinetically, this suppressive E-receptor factor directly competes with monoclonal antibody directed to the sheep erythrocyte receptor of human peripheral T lymphocytes and exhibits noncompetitive-type inhibition of DNA synthesis induced by phytohemagglutinin.

Present status of the zinc glycinate marker (ZGM)

ZGM was purified from both primary and metastatic colonic carcinomas demonstrably positive for ZGM by immunofluorescence microscopy. ZGM purification included preparative Pevikon electrophoresis, Sepharose 4B molecular exclusion chromatography and Con A‐Sepharose affinity chromatography. ZGM had an α2 electrophoretic mobility, an estimated molecular weight by Sepharose 4B equal to or greater than 2 × 106, and did not bind to Con A‐Sepharose, although having determinants with CEA‐like activity. Its immunologic activity was resistant to trypsin or phospholipase A but not to neuraminidase. Antisera prepared to ZGM and absorbed with saliva, when tested by double immunodiffusion, formed a single precipitation line with saline extracts of colon tumors and did not cross‐react with CEA, AFP, normal tissue extracts, ferritin, NCA, NCA‐2, CSAp, blood groups A, B, H, Lewis antigen, or buffy coat, alpha‐2 macroblogulin, saliva or ovarian cyst fluid. Immunofluorescence microscopy confirmed the presence of ZGM in 40 out of 45 adenocarcinomas of the GI tract staining primarily in tumors, the apical cytoplasm, and in grossly nonmalignant tissues, the deep crypts of the villi, while all of 22 non‐GI tumors in the study were ZGM negative.