Transfer of sensitised Lyt 2+ cells triggers acute rejection of pancreatic islet allografts

The cellular requirements for rejection of cultured islet allografts, a tissue expressing only class I alloantigens, have been studied. The results obtained show that sensitised Thy 1+, Lyt 2+ lymphocytes and not Lyt 2- lymphocytes trigger acute graft rejection.

Human allogeneic responses: lymphokine requirement for the in vitro generation of specific cytotoxic responses to a malignant melanoma cell line

Requirements for the in vitro generation of specific cytotoxic responses by human T-lymphocytes to an allogeneic malignant melanoma cell line (MM-170) have been examined. The responder T-lymphocytes used were isolated from peripheral blood and were essentially free of non-specific cytotoxic effector cells and their precursors. MM-170 alone was found to be an inadequate stimulator of cytotoxic responses. Stimulation did occur in cultures with both MM-170 and an Interleukin-2 containing human lymphokine supernatant. The cytotoxic effector cells generated were specific for MM-170 when the MM-170 cells used for stimulation had been metabolically inactivated by glutaraldehyde treatment.

Lymphokine production by peripheral blood leucocytes: quantitation of T-cell growth factor activity for assessment of immune response capability

Mitogen stimulation of as few as 200,000 human peripheral blood leucocytes (PBL) in 0.2 ml volumes produces highly active lymphokine supernatants. The lymphokine activity measured is T-cell growth factor. Under optimum conditions of PHA-P concentration, serum source and concentration, and time, activity is detectable to a dilution of between 1/250 and 1/700 for lymphokine supernatants from PBL of normal donors. Lymphokine supernatants prepared from PBL of donors previously treated with the immunosuppressive regimes of radiotherapy and/or chemotherapy had activities that were between 13% and 66% of normal controls. Lymphokine production as a quantitative measure of immune capability is discussed.

The generation of specific cytotoxic responses by human lymphocytes requires antigen and activities provided by a lymphokine supernatant

The requirements for the generation of specific cytotoxic responses by human lymphocytes have been investigated using as a model system the response to the ultraviolet light-killed mouse tumour P815. These requirements are antigen (P815UV) and activities provided by a human lymphokine (LK) supernatant. Cells that give rise to non-specific cytotoxicity can be separated on discontinuous Percoll density gradients after a 3-day incubation of peripheral blood leucocytes with the lymphokine supernatant. Cells from which specific cytotoxic responses can subsequently be generated in the presence of P815UV and LK sediment at a higher density.

A method for the production and quantitative assay of human lymphokine preparations

A procedure for the preparation and assay of a human lymphokine supernatant is described. Tonsillar lymphocytes at a concentration of 2 X 10(7)/ml in a serum-free medium are incubated for 2 h with PHA-P, washed free of unbound mitogen and incubated for a further 17 h. The supernatant is harvested and concentrated, and the active protein fraction is absorbed to and eluted from a column of hydroxylapatite. The eluate is desalted and sterile filtered. The preparations contain active material released from 10(8) cells in 1 ml and do not contain residual PHA-P. The most active preparations are obtained using PHA-P as the mitogen and at concentrations of 25-50 microgram/ml during the 2 h pulsing period. Activity is assessed by a quantitative assay based on the maintenance of mitogen activated blast cells in culture for 2 days.

An improved assay for interleukin 2 (lymphocyte growth factor) produced by mitogen-activated lymphocytes

The continued proliferation of activated T cells requires the presence of a lymphocyte growth factor in the culture medium. This study describes a rapid, highly reproducible assay to quantitatively measure levels of this lymphokine. The use of Concanavalin-A blast cells given this assay a high degree of flexibility and convenience. It is shown that the lymphokine measured is interleukin 2. The presence of an inhibitor in the supernatant of mitogen activated lymphocytes and the species specificity of the factor are demonstrated.

A high frequency of cytotoxic precursor cells for a syngeneic tumour

The average frequency of cytotoxic precursor cells in DBA/2 lymph node cell preparations reactive to the syngeneic tumour P815 has been determined as 1 in 2000. This frequency is similar to the precursor frequency for an allogeneic tumour EL-4. The normal lack of response of DBA/2 lymph node cells to the syngeneic tumour P815 in vitro cannot be attributed to a lack of cytotoxic precursor cells. We conclude that in this tumour-host system non-immunogenicity reflects a defect at the inductive step.

Cytotoxic T cell responses to a syngeneic tumour: conditions for primary activation in vitro

Primary cytotoxic responses of DBA/2 lymph node cells to a syngeneic tumour (the mastocytoma P815) have been generated in vitro. The development of these responses is dependent on the addition of a soluble factor (CSCS) which is produced by concanavalin A-activated spleen cells. The response is mediated by T lymphocytes, can be detected at low effector to target cell ratios and is directed against P815 tumour-associated antigens.

Malarial immunodepression in vitro: adherent spleen cells are functionally defective as accessory cells in the response to horse erythrocytes

The basis for the depressed response of malarial infected mice to horse red blood cells (HRBC) has been studied in vitro. Results presented show that the adherent spleen cells from infected mice (a) are defective in their ability to allow nonadherent spleen cells of both normal and infected mice to respond to HRBC whereas a response does occur with adherent spleen cells from normal mice (b) do not suppress the response of unfractionated spleen cells from normal mice to HRBC (c) contain phagocytic cells as measured by the uptake of neutral red in numbers which are of the same order of magnitude as in adherent spleen cells from normal mice, but which are unable to take up HRBC. We conclude that a splenic adherent cell, probably the macrophage is functionally defective as an accessory cell in the response to HRBC of mice infected with Plasmodium berghei yoelii.

Seasonal Variations in the Vitamin a Content of Victorian Butterfat

The total vitamin A potency of butterfat (dertved from cheese or butter) has been determined on samples from three different Victorian districts and from King Island in Bass Strait in 1945 and 1947-48. Carotene was determined colorimetrically and the Carr-Price test was used for vitamin A. The glycerol dichlorhydrin reagent was too insensitive.