The mixed-leukocyte reaction in man: effect of pools of stimulating cells selected on the basis of crossreacting HL-A specificities

Cell titration assay for measuring blastogenesis of bovine lymphocytes

The blastogenic response of bovine peripheral blood lymphocytes to phytohemagglutinin (PHA) and to microbial antigens was measured using a lymphocyte titration assay. Culture conditions, including lymphocyte concentrations, incubation periods and medium formulation, were established which produced linear or nearly linear responses over a range of cell concentrations. These conditions were established by testing lymphocytes from unimmunized cattle and from heifers infected with Brucella abortus with PHA and a B. abortus extract. Four cell concentrations in 2-fold increments were selected for measuring responses to PHA (3.125 X 10(3) to 2.5 X 10(4) cells/well) and to antigens (5.0 X 10(4) to 4.0 X 10(5) cells/well). The strength of response varied among animals and also over time for individual animals, but the titration assay allowed exponential proliferation to be distinguished from decline, which may have been due to overcrowding of microtiter wells, exhaustion of nutrients or induction of regulatory events. This assay provided a more reliable and discriminating method of evaluating lymphocyte proliferation responses than that achieved by single point assays. The displacement of the titration curves could be used to estimate the relative frequency of lymphocytes responding to antigens or mitogens.

Optimum cell numbers for mixed lymphocyte responses in hanging-drop microcultures

The conditions required for optimum mixed lymphocyte culture (MLC) responses in hanging-drop (HD) microcultures in Terasaki trays have been investigated. Compared with conventional (200 microliter) MLC, HD-MLC required 5-10 times fewer cells, and 10% of the amount of culture medium and 3H-thymidine label. Peak uptake of label in HD-MLC was mutually responder-stimulator concentration dependent. Differences in response to related and unrelated lymphocytes indicate that HLA-D determinants are detected in HD-MLC.

Mixed lymphocyte cultures (MLC) and acute pancreatitis after renal transplantation

MLC was performed preoperatively in 35 out of 57 candidates for renal transplantation. Three patients developed acute pancreatitis in the early postoperative stage, 2 of them died. In these three cases MLC revealed complete non-reactivity of the recipient lymphocytes, compared with the donor as well as with the positive control lymphocytes. None of the other patients showed this phenomenon and none of them developed acute pancreatitis. It is suggested that the recipient's immune responsiveness may be involved in the aetiology of the production of acute pancreatitis after renal transplantation.

Influence of HLA-A and HLA-B cross-reactive antigen matching on kidney graft survival

The presence of cross-reactive (CR) antigens of the HLA-A and B specificities between donor and recipient carries a better graft outcome than an HLA match not taking it into account. This influence of CR antigens has been observed in the case of cadaver kidneys matched only for none or one HLA antigen. If two or more antigens are matched this effect is not seen anymore. This improved graft survival could not be explained on the basis of the number of transfusion nor the incidence of cytotoxic antibodies.

The HLA-D system: at least two loci and four distinct phenotypic traits per haplotype. Introduction to component typing in families and population by primed lymphocyte typing

Using a number of intrafamilial PLTs raised against identical HLA haplotypes it has been possible to construct a model in an informative family defining the HLA-D region as a genetic system. This system consists of at least two regions separated by a recombination between HLA-D and GLO. In relation to the site of recombination, a minimum of one centromeric and three telomeric components can be identified per haplotype. - Fourteen PLTs raised and defined within the family were subsequently tested in a Caucasian population (n = 84) and in 13 unrelated, complete families. - It is concluded that the hypothetical model proposed for the HLA-D regions as a genetic system of linked loci, coding at the cell surface for associated but distinct components (at least four per haplotype), allows for typing of the components of the HLA-D system of any given haplotype. Serological typing of HLA-D components should, in the near future, provide a more convenient way of establishing component phenotypes than the present use of primed lymphocyte typing reagents. Among the components isolated, some have a high association with the classic alleles defined either by homozygous typing cells or DR serology. Others form the basis of cross-reactivity but their presence does not interfere with standard typing. Others, however, seem by their mere presence to be responsible for false assignments. - The concept of HLA-D as a genetic system clarifies many of the inconsistencies observed with a one-locus system.

Diminished mixed lymphocyte response in ankylosing spondylitis

A diminished mixed lymphocyte response was reported by Nikbin et al. (1976) among patients with ankylosing spondylitis, their asymptomatic relatives and also normal controls carrying the B27 antigen. In the present communication, the responses in 48 ankylosing spondylitis patients and 45 controls were examined in mixed lymphocyte cultures tested against a 'standard stimulator' made up of pooled lymphocytes. A significantly diminished response is confirmed among the ankylosing spondylitis patients, but not in the control group carrying the B27 antigen. The diminished mixed lymphocyte response therefore appears to be more directly associated with the disease than with the B27 antigen, and possibly represents a specific T-cell defect associated with the pathogenesis of the disease.

Mixed lymphocyte culture search for HLA-D homozygous typing cells in the Hungarian inbred population of Ivád

Six functionally HLA-D homozygous typing cells were identified by a restricted investigation into the Hungarian inbred population of Ivád. These putative HLA-D homozygous typing cells were then tested against a highly selected Scandinavian population sample of 60 individuals previously typed by histocompatibility reference reagents. The different HLA-D specificities could thus be identified: one closely matching HLA-Dw5, another resembling the Oslo LDoH specificity, while the last seems to be unique. Only one of the typing cells thus ascertained were HLA-B homozygous and were selected on the basis of the Ivád family structure and not on the basis of serological HLA typing.

MLC (HLA-D) typing: a family study

The genetics of five HLA-D specificities (Dw1, Dw2, Dw3, Dw4 and Dw6) have been assessed in 21 normal families with four or more children. The HLA-D traits, as defined by typing response against homozygous typing cells, normally behave as dominant characters. The data support the concept of allelic factors. The locial flaw in the basic algorithm of MLC typing (HLA-D typing), i.e. to draw positive conclusions from negative observations, has been amply reinforced in the following studies. Five assignments could not be verified genetically under the assumption of dominant traits. Homozygous lack of specific response genes is among the mechanisms proposed as a cause for the phenomenon which has not yet been fully explained. The estimated magnitude of the frequency of false assignments is approximately 10%.

Demonstration of the production of human thyroid-stimulating immunoglobulins (HTSI) by Graves' lymphocytes cultured in vitro with phytohaemagglutinin (PHA)

The lymphocytes from patients with Graves' disease or from healthy subjects have been cultured in vitro either alone or with phytohemagglutinin (PHA). After six days the culture supernatants have been assayed for their human thyroid-stimulating activity by measuring increases in adenosine 3',5' monophosphate (cyclic AMP) in human thyroid slices with which the supernatants have been incubated. Significant levels of human thyroid stimulator activity were found in the culture in which Graves' lymphocytes were cultured with PHA. This activity has been abolished by precipitation of the IgG from the culture supernatant with goat antihuman IgG serum. In contrast, when Graves' lymphocytes were cultured alone, or when control lymphocytes were cultured either alone or with PHA, there was no overall significant production of human thyroid-stimulating immunoglobulin (HTSI). It is concluded that Graves' lymphocytes can be stimulated by PHA to produce HTSI in vitro. Since PHA is known to stimulate only the T lymphocytes, which do not themselves elaborate immunoglobulins as the B lymphocytes do, the above observations indicate a cooperation between T and B lymphocytes in the production of HTSI, at least in this system.

Mixed leukocyte reaction in rheumatoid arthritis

The mixed leukocyte reaction (MLR) responses of 29 patients with classic rheumatoid arthritis (RA) were compared with those of 24 age- and sex-matched healthy controls. Pools of stimulating cells were selected to include the major cross-reacting HL-A specificities. In pooled human serum the MLR response of the RA lymphocytes was significantly enhanced relative to the response controls (P less than 0.05). In autologous serum there was suppression of the MLR response in patients with RA which correlated with disease activity. The data suggest the presence of an intrinsically enhanced cellular reactivity of RA lymphocytes suppressed by serologic factor(s). The mechanisms of this enhancement of suppression are discussed.

A simple freezing and storage method to preserve the stimulating function of leukocytes in the mixed leukocyte reaction

Human peripheral blood leukocytes retain their capacity to function as stimulating cells in the one way MLR after freezing and storage at - 70 degrees C by a simple and inexpensive method. This storage method facilitates the use of a standard stimulating pool of cells from three donors which may provide a quantitative assay for testing the ability of cells to respond to allogeneic cells in culture.

Inhibition of mitogen mediated lymphocyte blastogenesis by adenosine

The effect of adenosine on the proliferative response of human peripheral circulating lymphocytes to stimulation by concanavalin A, phytohemagglutinin and pokeweed mitogen was evaluated. Increasing concentrations of adenosine substantially inhibited mitogen mediated lymphocyte blastogenesis. Erythro-9(2-hydroxyl-3-nonyl) adenine. HCl enhanced the inhibitory effect of adenosine. Inosine, the deamination product of adenosine, had an inhibitory effect which was less than that of adenosine. Inhibition by adenosine may be relevant to the normal regulation of immune function and may account in part for the pathophysiological relationship between severe combined immunodeficiency disease and adenosine deaminase deficiency.