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Biomedical subjects

K Krohn

Publications and source records attributed to K Krohn.

At least 145 records · Page 8Linked to original sources
PubMed1987

Long latency precedes overt seroconversion in sexually transmitted human-immunodeficiency-virus infection.

Signs of latent HIV infection were sought in stored serum samples collected before overt seroconversion, confirmed by enzyme-linked immunosorbent assay (ELISA), from 9 subjects with human-immunodeficiency-virus (HIV) infection, in serum from 25 seronegative sexual partners of HIV-seropositive men and from 23 other seronegative, homosexually active men. Free HIV antigen and/or low-titre antibodies to recombinant structural (core, env) or non-structural (3' orf, sor, tat) proteins were seen 6-14 months before seroconversion in all 9 subjects who seroconverted. Antibodies against core proteins detected by western blot were usually the first sign of latent HIV infection. 5 of the 25 ELISA-negative exposed partners have shown HIV antigenaemia and antibodies against core proteins for 16-34 months. By in-situ hybridisation, HIV-specific RNA was detected in peripheral-blood non-lymphoid mononuclear cells in some of the latently infected partners. All subjects with latent HIV infection had normal numbers of T4 lymphocytes but half of them lost their in-vitro proliferative T-cell response to a recall antigen (purified protein derivative of tuberculin). Early HIV infection, characterised by a low-level and restricted antibody response towards HIV core and regulatory proteins, seems mainly to affect antigen-presenting cells.

Acquired Immunodeficiency Syndrome↗
PubMed1987

The use of an HTLV-I-infected human T-cell line (ATH8) in an interleukin-2 bioassay.

Biological interleukin-2 (IL-2) assays require cells that proliferate only in the presence of IL-2. The most often used human cells for this purpose have been phytohaemagglutinin (PHA)-stimulated buffy coat lymphocytes made dependent on IL-2. The results obtained by this T-blast method have not been easily reproducible and/or comparable due to differences in individual buffy coat batches. Murine cytotoxic T-cell lines (CTLL and CTLL-2) have been widely used in human IL-2 assays, but there remains a need for a human cell line. We have developed an IL-2 bioassay, based on the use of a human HTLV-I-infected Th-cell line, ATH8. These cells express IL-2 receptor and are totally dependent on extrinsic IL-2 for proliferation. The results of the ATH8 IL-2 assay were reproducible and comparable to those obtained with successful T-blast assays. ATH8 cells do not require a prolonged culture period before they are suitable for the IL-2 assay as do T-blasts.

Biological Assay↗
PubMed1987

Transverse myelitis and optic neuritis in systemic lupus erythematosus: a case report with magnetic resonance imaging findings.

We describe a patient with systemic lupus erythematosus who developed transverse myelitis and optic neuritis. Magnetic resonance imaging showed the presence of an abnormal signal in a normal-sized spinal cord which corresponded to the patient's neurologic deficit. No abnormality was recognized in either optic nerve. Magnetic resonance may prove to be a useful imaging modality for the diagnosis of a transverse myelopathy in systemic lupus erythematosus.

Adult↗
PubMed1987

Precipitating and non-precipitating monoclonal antibodies against chicken avidin. Significance of epitope density.

1. Monoclonal antibodies, generated against chicken avidin, were characterized in Ouchterlony's immunodiffusion. 2. Of the nine antibodies three were non-precipitable but six could form clear visible precipitation lines with egg-white avidin in agarose gel. 3. The latter six antibodies could be divided into two groups according to their reactive pattern in immunodiffusion. 4. Antibodies belonging to the first group precipitated both dimeric as well as tetrameric avidin molecules, while those of the second group precipitated only the tetrameric avidin molecules. 5. The relevance of these results to the structure of avidin as well as possibilities to use monoclonal antibodies and the immunodiffusion technique to compare the structure of avidin induced by different factors are discussed.

Animals↗
PubMed1987

Specific cellular immune response and neutralizing antibodies in goats immunized with native or recombinant envelope proteins derived from human T-lymphotropic virus type IIIB and in human immunodeficiency virus-infected men.

Animals immunized with native or recombinant envelope proteins from the human immunodeficiency virus (HIV, formerly referred to as human T-lymphotropic virus type III) human T-lymphotropic virus type IIIB and naturally HIV-infected men were assessed for neutralizing antibodies and cell-mediated immunity toward the virus. Immunization of rabbits or goats with the native external envelope glycoprotein gp120 or with corresponding recombinant proteins elicited strictly type-specific neutralizing antibodies. A broad, group-specific cellular immune response to gp120 and to three different HIV isolates was seen in goats immunized with the native gp120 but not in animals immunized with the nonglycosylated recombinant envelope proteins. In HIV-infected people, no T-cell response was seen, even though their T-cell response toward other foreign antigens was intact. The results show type- and group-specific epitopes on gp120, some of which may be of importance for the development of a vaccine against HIV infection.

Acquired Immunodeficiency Syndrome↗
PubMed1987

Humoral immune response to the entire human immunodeficiency virus envelope glycoprotein made in insect cells.

The human immunodeficiency virus envelope gene was expressed in insect cells by using a Baculovirus expression vector. The protein has an apparent molecular mass of 160 kDa, appears on the surface of infected insect cells, and does not appear to be cleaved to glycoproteins gp120 and gp41. Goats immunized with the 160-kDa protein have high titers of antibody that neutralizes virus infection as measured by viral gene expression or cell cytolysis. In addition, immune sera can block fusion of human immunodeficiency virus-infected cells in culture. Both neutralization and fusion-blocking activities are bound to and eluted from immobilized gp120.

Animals↗
PubMed1987

Acute multiple sclerosis exacerbations are characterized by low cerebrospinal fluid suppressor/cytotoxic T-cells.

The present study describes peripheral blood (PB) and CSF T-lymphocyte subpopulations in 55 MS patients with and without acute exacerbation and compares the results with those obtained from 8 with CNS infections and 45 with other neurological disorders or symptoms (OND). The MS patients were most strongly characterized by a decline of their CSF suppressor/cytotoxic T-cells, which was most profound during acute exacerbations. The proportional amount of CSF helper/inducer T-cells (Th) was higher in both MS group than in the OND group, but not different from that of the CNS infection group. No statistically significant change in the CSF Th-cells during exacerbations was seen. MS patients without an exacerbation had somewhat higher levels of their PB Th-cells than the patients with OND, but otherwise no differences in the PB T-cell subsets were seen.

Cerebrospinal Fluid↗
PubMed1987

The validity of immunological studies in human immunodeficiency virus infection: a three-year follow-up of 235 homo- or bisexual persons.

During a three-year follow-up study of 235 risk-group people living in Finland, we found a slow increase in the proportion of HIV seropositives (from 9.8% to 14.0%) and a slow but continuous advance in symptoms typical of HIV infection among them. The first immunological changes after HIV seroconversion were an increase in Ts-cells and a decline in antigen-induced T-cell functions (proliferation, IL-2 production). A further decline in antigen-induced responses was seen before early clinical symptoms and signs of HIV infection developed. During later phases of HIV infection the decrease of Th-cells and the elevation of serum Beta-2 microglobulin correlated most strongly with the progression of HIV infection. The mitogen-induced lymphocyte functions of the HIV-infected correlated to Th-cell levels, while the antigen-induced proliferation and IL-2 production showed correlation neither to Th-cells nor to Ts-cells. The poor antigen-induced T-cell responses might be caused by abnormally functioning monocytes, known to be infected by HIV. Our results suggest that in HIV infection there is a continuous but slow disease progression, although individual variation may be great. The immunological parameter best predicting the prognosis of an infected person in the early phases of infection was the antigen-induced lymphocyte functions, and later the amount of Th-cells.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Recognition with a monoclonal antibody of a cytoplasmic mammary carcinoma antigen, correlated to the estrogen receptor status.

Immunohistochemical reactivity of mammary carcinomas with monoclonal antibodies (MAbs) to human milk fat globule (HMFG) membrane antigens was compared with the estrogen (ER) and progesterone receptor (PR) status of the tumors. Antibody III D 5 stained 55 of the 74 tumors studied, the reaction being of borderline intensity in 19 cases and unequivocally positive in 36 cases. The staining was always cytoplasmic; in addition occasional extracellular III D 5-positive secretory material was observed. Positive reactivity of the tumor with antibody III D 5 was significantly correlated with ER and/or PR content of the tumors. The presence of extracellular, III D 5-positive secretory material correlated to the ER but not to the PR status of the tumors.

Animals↗
PubMed1986

Reactivity of a monoclonal antibody recognizing an estrogen receptor regulated glycoprotein in relation to lectin histochemistry in breast cancer.

We have raised monoclonal antibodies against human milk fat globule membrane antigens and previously shown that one of them, called III D 5, recognises a glycoprotein associated with estrogen receptor activity of breast cancer. In immunoblotting it was shown that the molecule in human milk exclusively stained with III D 5 also binds peanut agglutinin (PNA) and Ricinus communis. In this study we correlate the staining of III D 5 and binding of lectins to tissue sections fixed in formalin and embedded in paraffin. Similar reactions were seen only with III D 5 and PNA. Our results suggest that III D 5 and PNA detect overlapping antigenic epitopes in mammary carcinoma. This is in keeping with previous results that PNA or III D 5 reactivity is correlated with estrogen receptor status of breast cancer.

Antibodies, Monoclonal↗
PubMed1986

Lectin binding affinities of human milk fat globule (HMFG) membrane antigens.

Six biotinylated lectins with differing specificities and two monoclonal antibodies (III D 5 and III H 2) were used to characterize the sugar-residues in human milk fat globule (HMFG) membrane antigens. Immunoblotting analysis revealed that most of the antigens contain several sugars. However, the molecules exclusively reacting with anti-HMFG III D 5, a monoclonal antibody previously shown to detect antigen(s) positively correlating with the expression of estrogen receptors in mammary and gynaecological carcinomas, could only be stained with peanut agglutinin and Ricinus communis-lectins. One of these antigens, a 42-57 kDa molecule, was shown to have a complexed quaternary structure with galactose determining the antigenic specificity. It is suggested that the production of this glycoprotein in estrogen sensitive tissues results from activation of galactosyl-transferase-enzyme at the same time as the expression of estrogen receptors.

Binding, Competitive↗
PubMed1986

Seropositivity to LAV/HTLV-III in 11 European countries.

The ECP Working Group on AIDS has evaluated data on seropositivity to LAV/HTLV-III supplied by members in II Western European countries. The period covered is 1981-84. The rise in LAV/HTLV seropositivity parallels the incidence of cases of AIDS in the different countries. LAV/HTLV now spreads freely within Europe and spread has become less dependent upon promiscuity. The epidemic is about to enter Eastern Europe. Intravenous drug abusers appear to be the risk group experiencing the most rapid spread at present. Furthermore, seropositivity in males and females outside the traditional risk groups seems on the rise, and as in the US the percentage seronegative in individuals with PGL is quite high. AIDS is rapidly becoming a major cause of cancer in young adults. A coordinated European preventive effort is urgently needed.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Immunohistochemical reactivity of monoclonal antibodies to human milk fat globule with breast carcinoma and with other normal and neoplastic tissues.

The immunohistochemical reactivity of three monoclonal antibodies, generated against human milk fat globule membranes (HMFG), were studied using peroxidase conjugated secondary antibody or avidin-biotin-peroxidase complex method. Two of the antibodies, III E 8 and III H 2 showed rather broad reactivity, staining all mammary, ovarian, endometrial, cervical and bronchial adenocarcinomas. They also stained all pancreatic adenocarcinomas but only 30% of the carcinomas of the colon. Reaction with prostatic and renal adenocarcinomas varied. No reaction was seen with squamous or transitional cell carcinomas. Antibody III D 5, which previously has been shown to recognize an estrogen receptor activation associated antigen in mammary carcinomas, stained 60% of mammary or gynecological adenocarcinomas. This antibody had a more limited reactivity with other tissues as well, as all intestinal carcinomas were negative. It stained all bronchial adenocarcinomas, however, and 50% of the prostatic carcinomas. The three monoclonal antibodies, although not specific, show a more restricted reactivity than the so far described HMFG antibodies and they may therefore be of value in histopathological diagnosis.

Adenocarcinoma↗
PubMed1986

Interleukin 2 production in HTLV-III/LAV infection: evidence of defective antigen-induced, but normal mitogen-induced IL-2 production.

We studied mitogen- and antigen-induced interleukin 2 (IL-2) production in HTLV-III/LAV infected and non-infected individuals and compared the results with T cell subpopulations, and with mitogen- and antigen-induced DNA synthesis and production of leucocyte migration inhibitory factor (LIF) in order to understand the controversial findings related to IL-2 production in HTLV-III/LAV infection. The HTLV-III/LAV antibody positive group showed immunological defects: low T helper (Th) cells, high T-suppressor (Ts) cells, reduced mitogen- and antigen-induced DNA-synthesis, but LIF production comparable to the HTLV-III/LAV antibody negative group. The total amount of IL-2, produced either as a response to a mitogenic stimulus or as a response to a soluble antigenic (purified protein derivative of tuberculin, PPD) stimulus, was lower in the HTLV-III/LAV antibody positive group. However, adjusting the IL-2 production to the amount of Th-cells showed that the IL-2 produced by a standard number of Th-cells after mitogen induction was similar in HTLV-III/LAV infected and non-infected individuals. In contrast, the ability of Th-cells of infected persons to produce IL-2, or to proliferate as a response to a soluble antigenic stimulus, was considerably diminished. We conclude that HTLV-III infection leads to a selective incapability to mount a specific Th-cell response either due to an intrinsic defect in the Th-cell population or due to metabolic and/or functional disturbances in antigen-processing and presenting accessory cells.

Acquired Immunodeficiency Syndrome↗
PubMed1985

Characterization and partial purification of human milk fat globule membrane antigens by polyacrylamide gel electrophoresis and immunoblotting using monoclonal antibodies.

Polyclonal and monoclonal antibodies were used to characterize human milk fat globule (HMFG) membrane antigens, using gel filtration, ion exchange chromatography and western blotting. Although originally generated against HMFG, monoclonal antibodies also reacted with skim milk. In western blotting, several antigen molecules were seen, of which some were detected by all available antibodies, and one only with monoclonal antibody III D5, previously shown to react with mammary and ovarian carcinomas bearing estrogen receptors. This or these antigens, with a molecular weight of about 53 kd, were isolated by fractionation in SDS-PAGE. A low polypeptide content was demonstrated but the antigenic structure could be stained with periodic-acid-Schiff and biotinylated peanut agglutinin, indicating the presence of galactose or N-acetylgalactosamine residues. While this 53-kd molecule is the only determinant exclusively stained by III D 5 antibody, it is suggested that it carries epitopes related to estrogen receptor activation.

Antibodies, Monoclonal↗