LYMPHOCYTE PRODUCTION MEASURED BY EXTRACORPOREAL IRRADIATION, CANNULATION, AND LABELING TECHNIQUES

Immunology of bovine respiratory syncytial virus in calves

Bovine respiratory syncytial virus (BRSV) is an important cause of respiratory disease in young calves. The virus is genetically and antigenically closely related to human (H)RSV, which is a major cause of respiratory disease in young infants. As a natural pathogen of calves, BRSV infection recapitulates the pathogenesis of respiratory disease in man more faithfully than semi-permissive, animal models of HRSV infection. With the increasing availability of immunological reagents, the calf can be used to dissect the pathogenesis of and mechanisms of immunity to RSV infection, to analyse the ways in which the virus proteins interact with components of the innate response, and to evaluate RSV vaccine strategies. Passively transferred, neutralising bovine monoclonal antibodies, which recognise the same epitopes in the HRSV and BRSV fusion (F) protein, can protect calves against BRSV infection, and depletion of different T cells subsets in calves has highlighted the importance of CD8(+) T cells in viral clearance. Calves can be used to model maternal-antibody mediated suppression of RSV vaccine efficacy, and to increase understanding of the mechanisms responsible for RSV vaccine-enhanced respiratory disease.

T-lymphocyte perturbation following large-scale apheresis and hematopoietic stem cell transplantation in HIV-infected individuals

Analysis and mathematical modeling of T-lymphocyte perturbation following administration of granulocyte colony stimulating factor (G-CSF) and two large-scale aphereses are reported. 74 HIV-1 positive antiretroviral-treated individuals were infused with gene- or sham-transduced CD34+ hematopoietic stem cells (HSC) in a Phase II clinical trial. T cell numbers were examined in four phases: 1) during steady state; 2) increases in peripheral blood (PB) following G-CSF administration; 3) depletion post-aphereses and 4) reconstitution post HSC infusion. The present analysis provides the first direct estimate of CD4+ T cell distribution and trafficking in HIV-infected individuals on stable HAART, indicating that CD4+ T lymphocytes in PB represent 5.5% of the pool of CD4+ T lymphocytes that traffic to PB.

A controlled clinical trial of the immunosuppressive effect of extracorporeal irradiation of the blood in renal allotransplantation

The immunosuppressive effect of extracorporeal irradiation of the blood (ECIB) in renal allotransplantation (RAT) has been investigated in a controlled clinical trial. A series of 101 uremic patients undergoing intermittent hemodialysis in preparation for RAT were allocated randomly to two groups; a treated group +ECIB (n=55), and a control group 0-ECIB (n= 46). ECIB treatment was given in the form of a fixed dose, with a transit dose of 400 rad and a cumulative dose of approximately 50 000 rad, both before and after RAT. A selective long-term lymphocytopenia was usually obtained, with no effect on immunoglobulins, complements or plasma proteins. Erythrocyte count was reduced in the majority of cases, but this had no limiting effect on the implementation of treatment. The shortest survival times and most deaths occurred in the +ECIB group. The first rejection episode occurred later in the +ECIB group, but there was no difference between the groups in the number of rejections during the first two months or during the whole observation period. There were more cases with two or more rejection episodes in the +ECIB than in the 0-ECIB group. There was no difference in graft survival, but shortest patient survival and most deaths after RAT occurred in the +ECIB group. It must therefore be concluded that the immunosuppressive effect of ECIB has no practical clinical relevance in RAT, and that ECIB given in the manner described involves the possibility of side-effects so serious that the method cannot be recommended.

STUDIES ON THE LYMPHOCYTOSIS INDUCED IN MICE BY BORDETELLA PERTUSSIS

1. Intravenous injection into mice of phase I Bordetella pertussis vaccine resulted in a striking hyperleucocytosis with a predominating lymphocytosis. Intraperitoneal inoculation was less effective, and subcutaneous administration was inactive. 2. Active immunization prevented the hyperleucocytosis; passive immunization was less effective. 3. Reticuloendothelial blockage reduced the effect of the vaccine. 4. Extirpation of the spleen or thymus did not alter the leucocyte response. 5. Histologic studies suggested that the increase in circulating lymphocytes resulted from release of cells from lymphoid organs, including the thymus.

Biophysical investigations of the dose-effect relationship in chromosome aberrations of human lymphocytes caused by thorotrast deposits. II. Biological and medical aspects

The biological effect of alpha-radiation, which has been examined in this investigation, is the occurrence of chromosome aberrations in lymphocytes from the peripheral blood of Thorotrast patients. To set up a dose-effect relationship, it is necessary to estimate the absorbed dose of a single lymphocyte found in a blood sample. Then it would be possible to use chromosome aberrations of lymphocytes from peripheral blood as an indicator for estimating the effective radiation dose. The physical aspects of this investigation have been described in part I of this paper. In part II, biomedical considerations are described and discussed. The irradiation of the lymphocytes takes place in the whole lymphatic system, but the lymph node could have been used as a model for the lymphatic system. Based on the evaluation of size and distribution of Thorotrast conglomerates, the average annual dose in different structures of the lymph node has been determined. The Thorotrast content in lymph nodes depends on the region of the body from where the lymph nodes originate. It has been tried to compile the distribution of the lymph nodes in the different regions of the body. Annual doses have been calculated in these different regions in order to find a representative value for the whole body. The values describing the kinetics of the lymphocytes in the body have been used to convert the annual dose in lymph nodes into the dose of a lymphocyte found in a sample of peripheral blood. It is pointed out that the calculated dose of the lymphocytes, being 250 rad, is an estimation of an upper value. The lymphocytes are "in vivo" irradiated by the Thorotrast, but most of the calibrations used for biological dosimetry are referred to as "in vitro" experiments. The discrepancy between "in vivo" and "in vitro" results are discussed in the findings of this study and in other results.

Histopathological effects in mice of heterologous antilymphocyte serum

The effects of heterologous rabbit anti-mouse lymphocyte antiserum on the morphology of lymphoid and other tissues was investigated in CBA mice. The lymphoid tissues exhibited characteristic changes specific for ALS treatment, which were an invariable accompaniment to its immunosuppressive effects. These consisted of peripheral lymphopenia occurring at some time during a course of ALS treatment and persistent depletion of small lymphocytes in lymph node paracortical areas and splenic follicular periarteriolar zones. The thymic histology was generally well preserved. It is suggested that the relevant lesions reflect a rapid depletion of the pool of recirculating lymphocytes, possibly by a primary cytotoxic effect exerted on cells peripheral to lymphoid tissue. Other histologic features attendant to the administration of ALS were accounted for as consequences of immunization of ALS recipients to rabbit serum constituents or by the deleterious effects of antibodies directed against tissues other than lymphoid cells.