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Nuclei from lymphocytes which have been stimulated with phytohaemagglutinin (PHA) or concanavalin A (Con A) are capable of stimulating both T and B lymphocytes. The basis of the mitogenic properties of these nuclei has been investigated in more detail. Mitogen has been labelled with 125I and the various constituents of the nuclei (RNA, DNA and protein) have also been labelled in an attempt to determine their cellular localization during stimulation. The effects of competing sugars and inhibitory antisera have also been examined. The results of the experiments suggest that the mitogenic effects of nuclei may result from concentration or complexing of PHA or Con A either in the nucleus or on the nuclear membrane. [ABSTRACT FROM AUTHOR]

Thirty male patients with sexually acquired reactive arthritis (SARA) have been studied at the time of their initial presentation and thereafter. Chlamydia trachomatis was isolated from the urethral exudate of 9 (36.0%) of the 25 patients from whom urethral specimens were taken, and elevated titres of IgM antibody of C. trachomatis were detected in 11 (36.6%) of the 30 initial sera. Thirteen (43.3%) of the patients has a positive urethral culture and/or elevated titre of IgM antibody, and it is therefore suggested that 43.3% of these patients suffered an acute chlamydial infection at or near the time of the onset of their joint disease. The demonstration of 4-fold or greater rises and/or falls in IgM antibody titre (8 patients) and IgG antibody titre (6 patients) in a group of 15 men studied throughout the course of their disease strongly supports this conclusion. A positive urethral culture and/or raised titre of IgM serum antibody was also detected in 25 (50%) of 50 men with uncomplicated nongonococcal urethritis (NGU), suggesting that the prevalence of chlamydial infections in the 2 conditions is similar. Titres of IgG serum antibody to C. trachomatis were, however, significantly higher in patients with SARA than in those with NGU or other rheumatic diseases, and in healthy controls. The geometric mean titres (GMT) of IgG serum antibody in patients with SARA, NGU, rheumatoid arthritis, ankylosing spondylitis, systemic lupus erythematosus, and in healthy controls were 1:47.5, 1:8.6, 1:2.2, 1;2.2, 1:3.5, and 1:1.4, respectively. These findings suggest that an exaggerated antibody response to acute infection by C. trachomatis may be an important factor in the development of SARA in some but not all patients. [ABSTRACT FROM PUBLISHER]

Lymphocytes in chronic lymphatic leukaemia (CLL) were found to release labelled antibodies against surface antigens at a slower rate than healthy cells and `escape from sensitization' was similarly prolonged in the abnormal lymphocytes. This suggests that membrane turnover in CLL lymphocytes is abnormally slow. The leukaemic cells can be provoked to turn over antisera more quickly by prior exposure to mitogenic stimulation and if nuclear material is used as a mitogen, membrane turnover will increase to a rate approaching that observed in normal lymphocytes. Once this acceleration has been achieved the leukaemic lymphocytes no longer react to an antiserum with specificity for leukaemic antigens and this result suggests that the Ieukaemic state of the CLL cell may be controlled by the surface membrane. [ABSTRACT FROM AUTHOR]

Mixed leucocyte cultures performed between identical twins, siblings of one family and unrelated individuals were evaluated by measurement of the uptake of 14C-thymidine and by their cytotoxic effect upon an allogenic target cell line (Chang liver cells). A close correlation was found between HL-A compatibility and 14C- thymidine uptake in all three situations, whilst no significant relationship existed between cytotoxicity and either histocompatibility or DNA synthesis. It is suggested that these two reactivities are distinct but are both influenced (although to a different extent) by differences in histocompatibility. [ABSTRACT FROM AUTHOR]

In one way mixed cultures between normal and acute leukaemic cells, cytotoxic effect was assessed by the subsequent amount of isotope released from 51Cr labelled allogeneic target cells (Chang liver cells). Observations were made during the acute phases and, where possible, in remission. All cells used in these cultures were of known HL-A phenotype. Normal lymphocytes exhibited a variable response to leukaemic cells. In many cultures the increased cytotoxicity was greater than that found after mixed cultures of normal cells. This was not related to the number of circulating blast cells nor directly to HL-A differences between cells. [ABSTRACT FROM AUTHOR]

When nuclei from the lymphocytes of mice immunized with rabbit erythrocytes are injected into unprimed animals the number of cells forming antibody to rabbit erythrocytes increases to a level approaching that of the immunized donor animals. The specificity of the response induced by nuclei is equally as good as that induced by native antigen. When ‘T’ and ‘B’ mice are immunized with rabbit erythrocytes a poor response is observed but when the nuclei from primed ‘T’ animals are used to immunize ‘B’ mice the number of antibody-producing cells is very much increased. In view of current theories about cellular co-operation it is pointed out that this co-operative effect of ‘T’ lymphocyte nuclei is independent of both cell membrane and additional antigen. [ABSTRACT FROM AUTHOR]

It has been shown that nuclei from lymphocytes stimulated with either PHA (Pegrum, Perera and Thompson, 1972), Con A or pokeweed have marked mitogenic properties. The ability of various lymphoid tissues to respond to such nuclear material differs from the response they show to the mitogens themselves, nuclei from rat lymphocytes stimulated with PHA or Con A will activate the lymphocytes from either spleen, bone-marrow or thymus whilst nuclei from pokeweedstimulated cells appear capable of stimulating only the bone-marrow-derived lymphocytes. It is suggested that the ability of the nuclear material from PHA or Con A-stimulated lymphocytes to induce mitogenesis m bone-marrow-derived cells may relate to cellular co-operation; ‘T’ cell processing being a prerequisite for ‘B’ lymphocyte triggering. [ABSTRACT FROM AUTHOR]

Normal and leukemic lymphocytes from healthy donors and patients with chronic lymphatic leukaemia exhibit increased DNA synthesis in 'one way' cultures with foetal cells, Leukaemic blast cells do not react. Foetal thymocytes showed a marked response to both normal and leukemic cells in mixed cultures. Leukaemic lymphocytes in particular caused a marked increase in [³H]thymidine uptake, suggesting a wider antigenic disparity between the leukemic and thymic cells. Lesser increases of DNA synthesis were produced in foetal liver cells and none in spleen cells. [ABSTRACT FROM AUTHOR]

Methods of platelet adhesiveness to glass and celite have been developed. The technical merits of these methods have been compared with a method using adenosine diphosphate (ADP). The aspects of platelet stickiness measured by the various techniques may be somewhat different. Bearing this in mind, the reproducibility of the results using each of the three methods has been assessed on a series of healthy donors. [ABSTRACT FROM PUBLISHER]

It is known that after mixed culture lymphocytes exhibit an increase in cytotoxicity to a target cell. The present study was undertaken to see if the degree of cytotoxicity was also related to HL-A differences. A cytotoxic effect was found where there was antigenic disparity. The degree was unrelated to the number of different antigens at the HL-A locus but cytotoxic effect was absent in cultures where there was complete HL-A identity using lymphocytes from twins, siblings and unrelated persons. [ABSTRACT FROM AUTHOR]