Lymphocyte stimulation by allogeneic and autochthonous cultured lymphoid cells

Staphylococcal protein A primed leukocytes enhance the autologous mixed lymphocyte reaction

Human peripheral blood mononuclear cells (PBMC) were preincubated for 3 days in medium alone or with various mitogens then washed and irradiated. The preincubated cells then were cultured with autologous T-cells in an autologous mixed lymphocyte reaction (AMLR). Staphylococcal protein A (SPA) pretreatment of PBMC enhanced autologous T-lymphocyte proliferation from 1375 +/- 321 cpm (mean +/- SEM untreated PBMC) to 42,467 +/- 7,985 cpm (SPA primed PBMC) (p less than 0.01). The ability of SPA treated PBMC to enhance the AMLR was not simply a reflection of their proliferation in preculture, as PBMC precultured with phytohemagglutinin and concanavalin A showed greater proliferation than SPA-treated PBMC yet only minimally enhanced the AMLR. Kinetic studies and pre-exposure of PBMC to graded doses of gamma radiation showed that SPA augmentation of the AMLR was mediated by 2 components which differed in kinetics and radiosensitivity. Although incubation of PBMC with SPA did not increase the percentage of cells with detectable surface Ia antigen, SPA did increase the density of Ia in the preincubated cells. Cell separation studies revealed that SPA enhancement of the AMLR was not mediated by T-cells, but was mediated by a non-adherent non-E-rosetting fraction of cells. SPA enhancement of the AMLR was associated with an increased Ia density in the stimulator population but not with an increase in Ia positive cells and was mediated by proliferation-dependent and proliferation-independent mechanisms.

Mixed lymphocyte reactivity in chimpanzees. I. Some technical and genetic aspects

One-way mixed lymphocyte culture (MLC) tests were performed among the members of five chimpanzee harems in all possible combinations: parents, parent-child, siblings and half-siblings. The technical aspects of MCL testing in chimpanzees appeared to be very similar to those observed for human and rhesus monkey MLC's. Two unexpected observations were made for which no satisfactory explanation can as yet be give: firstly, the occurrence of animals with consistently high autologous values and secondly, the existence of chimpanzees displaying low MLC responsive. The high autologous values occurred mostly in older imported animals (25% with high autologous values), while only one of the 45 laboratory born animals showed this phenomenon. Low responsiveness occurred in a few offspring belonging to a single harem only and is therefore likely to be genetically controlled but, as it appeared, not by genes linked to ChLA. Data suggesting the existence of an MHC-linked "major MLC" or D locus were confirmed and extended. A gene dose effect for D locus antigens was demonstratable, i.e., combinations of related animals differing for one showed lower MLC responses than combinations differing for two ChLA haplotypes. The number of D locus alleles was estimated to be 10.

HLA-D typing with lymphoblastoid cell lines. VI. Rationale and goals of data reduction

This report documents various characteristics of HLA-D typing by mixed leukocyte culture reactions when lymphoblastoid cell lines (LCLs) are substituted for peripheral blood lymphocytes as the stimulator cells. It also provides the rationale for designing the computer program described in the subsequent report. In such experiments, each donor to be HLA-D typed is stimulated with a panel of 30-50 HLA-D homozygous LCLs, each defined HLA-D allele being represented by several different human homogygous typing cells (LCT-HTCs). Variability in the strength of eahc donor's general response and in the strength of stimulation by each LCL-HTC makes it necessary to normalize raw data before the responses of various combinations can be compared and typing responses distinguished from non-typing responses. The autologous response and its equivalent effect among allogenetic combinations, the so-called "autologous-stimulation" effect, must also be distinguished from true allogeneic responses. The latter has been accomplished by "modelling," as described in the subsequent report. EBV-negative donors can also be HLA-D typed by this method despite the EBV-positivity of the LCL-HTCs. Preliminary analyses suggest that the HLA-D alleles defined by this method appear to segregate with appropriate haplotypes in family studies.

Lymphoblastoid cell lines are polyclonal activators of human T lymphocytes

Following stimulation with autologous or allogeneic lymphoblastoid cell lines (LCL) human T lymphocytes acquire two properties which suggest that LCL act as polyclonal activators. Cytotoxic activity, which has an antigen-specific component, is produced towards normal lymphocytes and LCL, and the cells become capable of mounting proliferative responses to antigens on human B lymphocytes which have accelerated secondary-type kinetics. Only weak responses to autologous cells occur. In addition, repeated restimulation with the original LCL leads to a progressive increase in the number of cells in the culture for a period of about 4 weeks. This approach may prove a useful way to grow large numbers of human T lymphocytes for further study.

Stimulation of T lymphocytes by autologous non-T lymphoid cells. Participation of HLA-D?

Non-T lymphoid cells were found to be able to stimulate autologous T cells in vitro. This "autologous" response was shown to be about 20% of the response to allogeneic unfractionated lymphocytes. The ability to induce autostimulation appeared to be a property of the Ig-positive lymphocyte fraction. Blocking experiments with allosera recognizing HLA-D-associated determinants suggested that the HLA-D determinants present on the stimulating cells might be involved in the stimulation of autologous T cells.

Cytotoxic antibodies to cultured human lymphoid cells in polytransfused thrombocytopenic patients: association with reduced survival of allogeneic transfused platelets

Four out of 8 thrombocytopenic patients without detectable cytotoxic antibodies to human peripheral lymphocytes contained cytotoxic antibodies to cultured human lymphoid cells. The presence of such antibodies was associated with reduced survival of infused allogeneic platelets in these patients. The antibodies reacted in a distinct fashion with a panel of cultured human lymphoid cells and are directed to B cell antigens. Cytotoxic antibodies to cultured human lymphoid cells did not react in vitro with platelets suggesting that the antibodies play no significant role in the accelerated destruction of infused allogeneic platelets, although their presence predicts it. Therefore, screening of sera with cultured human lymphoid cells appears to be a useful test in addition to those now used to select patients for transfusion of allogeneic platelets. Sera from polytransfused patients without cytotoxic antibodies to peripheral lymphocytes may be a useful source of antibodies to B cell antigens.

Lymphocyte transformation induced by autologous cells. II. Stimulation by mitogen-induced lymphoblasts

Lymphocytes incubated with phytohemagglutinin or concanavalin A develop the capacity to stimulate autologous lymphocyte transformation. This is not attributable to residual mitogen contaminating the lymphoblastic cell preparation as: (a) the dissociation of mitogen from the lymphoblastic cell preparation increases the degree of stimulation observed and (b) the kinetics of lymphocyte transformation stimulated by phytohemagglutinin-induced lymphoblasts is different from that stimulated by phytohemagglutinin. The appearance of the stimulatory determinants on lymphocytes exposed to phytohemagglutinin precedes morphological transformation.

Lymphocyte transformation induced by autologous cells: stimulation by cultured lymphoblast lines

The ability of cultured lymphoblasts to stimulate autologous lymphocyte transformation in "one-way" mixed leukocyte culture has been studied. Intact, cultured lymphoblasts required physical contact with responding lymphocytes to induce transformation. In quantitative terms, lymphocytes incorporate as much thymidine when mixed with irradiated cultured lymphoblasts as they do in response to phytohemagglutinin. The stimulation of lymphocyte transformation by allogeneic cultured lymphoblasts did not parallel the stimulation of lymphocyte transformation by leukocytes from the donor of the lymphoblast culture. The stimulatory determinants on the cultured lymphoblast are unaffected by neuraminidase but destroyed by trypsin. The trypsin-treated cultured lymphoblasts regain their capacity to stimulate autologous lymphocyte transformation within 48 hr in culture. Cultured lymphoblasts possess concanavalin A binding sites. Concanavalin A inhibits the capacity of cultured lymphoblasts to stimulate autologous lymphocyte transformation. The relevance of these findings to EB virus infection of cultured lymphoblasts and to immune surveillance is discussed.