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Biomedical subjects

I Milne

Publications and source records attributed to I Milne.

18 recordsLinked to original sources
PubMed1994

The effect of alpha 2 macroglobulin in commercial cytokine assays.

alpha 2 macroglobulin (alpha 2M), a 725 kDa plasma protein, has been reported to bind a range of cytokines. We have therefore investigated its effect on a number of commercial cytokine assays. The methylamine converted fast form of the molecule was found to reproducibly depress, by 26% or more, the standard curves obtained with certain commercial assays for IL-2 and for tumor necrosis factor alpha, and had a small inhibitory effect on some IL-4 assays. In contrast it slightly enhanced or had no effect on ELISAs for IL-1 beta and IL-6. The inhibition observed was directly proportional to the concentration of alpha 2 M used in the range 0.5-5 mg/ml. Studies in the IL-2 system also revealed that it was largely attributable to the fast form of alpha 2M. Preliminary evidence suggests that the effects observed may be dependent on the assay source. These findings may be relevant to the assay of biological fluids in which alpha 2 M is present.

Artifacts↗
PubMed1991

A two-site immunoradiometric assay for PTH(1-84) using N and C terminal specific monoclonal antibodies.

We report the development of a two-site immunoradiometric assay for PTH(1-84) based on two site-specific monoclonal antibodies--3B3 (radiolabelled antibody) specific for PTH(1-34) and ESQ1 (on solid phase) specific for PTH(74-84). Antibody 3B3 is sensitive to the oxidation of the methionine residues in PTH(1-34) therefore hydrogen peroxide (0.1 M) is added to the incubation mixture. Validation studies confirm quantitative recovery of both oxidized and reduced PTH(1-84). The assay has a minimum detection limit of 0.5 pmol/L and a range of 1.5-250 pmol/L with an intra-assay CV of less than 10% (2.8-250 pmol/L less than 5% CV). Studies on clinical samples indicate good discrimination between normal subjects (mean 2.21; range 1.0-5.0 pmol/L) and patients with primary hyperparathyroidism (mean 21.0; range 5.8-100 pmol/L) who in turn are well separated from patients with hypercalcaemia of malignancy (14/18 less than 0.5 pmol/L).

Adult↗
PubMed1985

Fluoresceinated alpha 2-macroglobulin as a probe for studying macrophages.

The potential value of fluorescein-conjugated human alpha 2-macroglobulin as a probe for studying macrophages in murine peritoneal exudate and spleen cell suspensions has been investigated using a fluorescence-activated cell sorter. These studies revealed that the number of alpha 2-macroglobulin-positive cells in the mixtures examined correlated closely with their macrophage content as determined morphologically. Furthermore cells separated on the FACS on the basis of their strong alpha 2-macroglobulin binding exhibited macrophage morphology and expressed Fc receptors on their surface. Conversely the alpha 2-macroglobulin-negative population contained few macrophages or Fc rosette-forming cells. Extensive blocking and comparative binding studies with a number of purified human alpha 2-macroglobulin preparations and derivatives thereof, and a variety of purified proteins, confirmed that the binding of fluorescein-conjugated alpha 2-macroglobulin to peritoneal exudate cells was specific. Furthermore the binding occurs in a highly reproducible manner. These observations suggest that fluorescein-conjugated alpha 2-macroglobulin in conjugation with flow cytometry is a sensitive and reliable method for both identifying and isolating subpopulations of macrophages.

Animals↗
PubMed1979

Further studies on antitumour responses induced by short-term pretreatment with syngeneic tumour cells.

The ability of s.c. injected tumour cells to specifically inhibit the growth of similar cells injected i.v. 2 days later has been confirmed. The capacity of tumour cells to elicit this effect varies form tumour to tumour. Furthermore, it is more readily achieved with cultured than with freshly excised tumour cells. The superior effect elicited by cultured tumour cells was not overcome by treating them with trypsin or pronase. The protection achieved was impaired in T-cell-depleted mice and mice which had been irradiated (400 rad) prior to pretreatment. In contrast, it was not affected by administration of silica, sodium aurothiomolate or cortisone acetate. The results imply that T-cell-dependent responses are involved in the protection conferred by pre-injecting tumour cells shortly before i.v. challenge.

Adenocarcinoma↗
PubMed1978

Antitumour responses induced by short-term pretreatment with tumour cells.

The injection (s.c. or i.p.) of 10(6) live or lethally irradiated methylcholanthrene-induced fibrosarcoma cells into CBA/Ca mice one or 2 days before i.v. challenge with the same tumour inhibited the formation of artificial lung tumour metastases. In addition, it also frequently enhanced the cytostatic effect of peritoneal exudate cells on monolayers of the same tumour. The effects on lung tumour metastasis were not noted if X-irradiated tumour was injected i.v., or if s.c. administration was delayed until one day after i.v. challenge. Similar effects on tumour growth were also observed in C3Hf/Bu mice and (CBA/Ca x A/HeJ) F1 hybrids which were pretreated (s.c.) with tumour shortly before i.v. challenge with the same tumour. Further studies in CBA/Ca mice suggested that the protective effect was tumour-specific, for the growth of i.v. injected tumour was not significantly inhibited by pretreatement with a number of other MC-induced or spontaneous tumours from the same and different strains.

Animals↗
PubMed1976

Antitumor antibodies and immunoglobulin class and subclass levels in Corynebacterium parvum-treated mice.

Changes in immunoglobulin class and subclass levels and the development of antitumor antibodies were assessed in normal and tumor-bearing mice challenged with Corynebacterium parvum. C. parvum administration resulted in a marked increase in certain immunoglobulin levels, especially Ig G2b, and in the development of antibodies reacting with syngeneic and allogeneic tumor cells. The serologic changes induced by C. parvum were dependent on the dose and route of administration; preliminary studies suggested that they may have been largly independent of T-cell function. These changes were suppressed by the administration of gold salts, which also inhibited the antitumor effect of C. parvum.

Animals↗
PubMed1975

Normal and pathological serum levels of alpha2-macroglobulins in men and mice.

The serum levels of alpha2-macroglobulin have been measured in normal men and mice and in a number of immunopathological conditions. Normal human concentrations are high in youth, reach their minimum in middle age, and gradually increase with old age. In all age groups the mean is higher in the female than in the male. Conversely, in normal mice the alpha2M level is low in youth, maximum in middle age, and shows a slight depression with old age, and the levels are frequently higher in males than in females; there are also strain variations. In human immunopathological conditions, there are some deviations from the normal alpha2M level but these are seen to be changes from the normal distribution of values around the mean, rather than significant elevation or depression of mean values. In some disease states studied there are differences between the sexes in the deviation from normal. "Abnormal" strains of mice had alpha2M levels within the range exhibited by "normal" mice but changes in the levels are seen in mice with various myelomas.

Adolescent↗
PubMed1974

The effect of transplanted methylcholanthrene induced fibrosarcomata and Corynebacterium parvum on the immune response of CBA and A-HeJ mice to thymus dependent and independent antigens.

The effect of transplanted syngeneic methylcholanthrene induced fibrosarcomata on the primary immune response of CBA and A/HeJ mice to standard doses of alum BSA, SRBC and SIII has been investigated. In animals with established fibrosarcomata the responses were (with one exception) either normal or elevated. Cell transfer studies in sublethally irradiated syngeneic recipients confirmed that the spleens from tumour bearing mice were capable of responding effectively to all 3 antigens. In animals simultaneously challenged with viable sarcoma cells and antigen the response to alum BSA was suppressed while those to SRBC and SIII were often enhanced. Furthermore the secondary response of A/HeJ mice to BSA was also suppressed by the simultaneous injection of viable fibrosarcoma cells. The administration of C. parvum 3 days after antigen had a variable effect. Nevertheless in a number of cases it significantly increased the primary response to all 3 antigens. It also inhibited the growth of the CBA fibrosarcoma but was without effect on the A/HeJ fibrosarcoma.

Animals↗