Effects of low dose irradiation on TK6 and U937 cells: induction of p53 and its role in cell-cycle delay and the adaptive response.

Purpose: To investigate the effect of small doses of radiation on the cell-cycle and related processes, and to determine the capacity of small doses of radiation to induce an adaptive response.

Materials And Methods: TK6, a lymphoblast cell line with wild-type p53, and U937, a monocytic leukaemia cell line with mutant, inactive, p53 were exposed to gamma ray doses ranging from 0.1 Gy to 3 Gy.

Immunological manifestations of HIV-infected children.

This cross-sectional study of stable HIV-infected children was designed to document the immunological manifestations of paediatric HIV infection and to determine whether inexpensive markers of immunosuppression could be identified. Investigations included lymphocyte count and subset analysis, levels of total protein, albumin, immunoglobulins, beta-2 microglobulin and neopterin. The median age of the 74 children studied was 16.

Cytokine-mediated inhibition of erythropoietin synthesis by dexamethasone.

The effect of inflammatory cytokines on the in-vitro synthesis of erythropoietin by HepG2 cells was evaluated. Monocyte-conditioned medium, and the cytokines interleukin-1 beta, interleukin-6 and tumour necrosis factor-alpha all reduced synthesis of erythropoietin. The steroidal anti-inflammatory drug, dexamethasone, did not affect cytokine-mediated erythropoietin inhibition.

Cellular immunity in tuberculous pleural effusions: evidence of spontaneous lymphocyte proliferation and antigen-specific accelerated responses to purified protein derivative (PPD).

The kinetics of in vitro cellular proliferation against a PPD of Mycobacterium tuberculosis or streptococcal antigen (streptokinase-streptodornase) was evaluated in pleural fluid and peripheral blood mononuclear cells (PBMC) from patients with tuberculous and non-tuberculous pleuritis. The peak proliferative response to PPD by mononuclear cells from pleural fluid occurred earlier (day 3) in 65% of patients with tuberculosis, a finding not seen in non-tuberculous effusions. Spontaneous lymphocyte proliferation of both peripheral blood lymphocytes and pleural effusion lymphocytes was frequently observed, irrespective of etiology.

Evidence for in vivo generation of cytotoxic T cells. PPD-stimulated lymphocytes from tuberculous pleural effusions demonstrate enhanced cytotoxicity with accelerated kinetics of induction.

Mycobacterium tuberculosis is a bacterial pathogen capable of survival and replication within human macrophages. Cytotoxic T cells are thought to be important for the eradication of infected macrophages. To test this hypothesis, pleural effusion lymphocytes from patients with tuberculous pleuritis were stimulated in vitro with PPD, and proliferation and cytotoxicity were assessed by thymidine incorporation and chromium release, respectively.