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This paper confirms results showing that TA3 tumour cells coated in vivo with immunoglobulins, lose some of the coat upon transfer to in vitro conditions. By labelling IgG isolated from the ascitic fluid of TA3 tumours it was found that the immunoglobulin coating TA3 cells is dynamically exchanged with immunoglobulin in the corresponding ascitic fluid. Some of the released immunoglobulin is in a degraded state as judged from the fact that most of the released material lost the antigenicity of intact immunoglobulin and has a lower capacity to precipitate with ammonium sulphate at 50% saturation. The degraded immunoglobulin has a higher binding efficiency to tumour cells. In vivo experiments demonstrated that the ascitic fluid of mice bearing TA3 and MCIM tumours contains a material which has some of the physicochemical properties of IgG but which does not precipitate with antisera directed aguinst IgG. [ABSTRACT FROM AUTHOR]

Partial purification of soluble products of guinea-pig lymphocyte activation (LAP) was undertaken by fractional precipitation with ammonium sulphate, ion-exchange and Sephadex chromatography, and by immune precipitation of inducing antigen and of contaminating serum protein. During these purification steps the activity of macrophage migration-inhibition factor (MIF) was concentrated up to 1300-fold and separated from inducing antigen and serum protein. An endpoint assay was devised for expressing antigen-induced MIF activity of LAP fractions as weights of material giving 30% inhibition of migration (MI30 doses). MIF activity precipitated between 50% and 80% saturated ammonium sulphate and eluted from DEAE-cellulose at pH 7-9 at intermediate salt concentrations (0-03-0-2 M phosphate). On Sephadex gel filtration MIF activity was concentrated in fractions of molecular weight range 56,000-82,000 with a smaller amount of activity eluting from 20,000-56,000. After immune precipitation of extraneous protein and elution from DEAE-cellulose, LAP material was found to have an MI30 dose of 0-4 /μg. Materials representative of antigen and serum protein-depleted MIF were selected for intralymphatic injection in order to determine whether MIF-rich LAP fractions were able to induce paracortical distension in guinea-pig lymph nodes (see following paper). [ABSTRACT FROM AUTHOR]

In this paper the specificity of the skin-reactive guinea-pig immunoglobulin in the homologous PCA test has been reconsidered. Extensive purification of this immunoglobulin by chromatographic methods results in the isolation of a small fraction or medium speed immunoglobulins that contains all skin reactivity. No correlation could be found with the 7S immunoglobulins IgGγ1 and Igγ1A suggesting a separate class of biologically active immunoglobulins. The PCA active antibody belongs to either an IgG subclass or is a heat stable homocytotropic antibody. Rabbit and chicken antisera against isolated fractions of guinea-pig immunoglobulins show the existence of 7S subclasses. Some suggestions for a revised nomenclature are given. [ABSTRACT FROM AUTHOR]