Genetic control of thymus-derived cell function. I. In vitro DNA synthetic response of normal mouse spleen cells stimulated by the mitogens concanavalin A and phytohemagglutinin

Reutilization of Tacrolimus Extracted from Expired Prograf® Capsules: Physical, Chemical, and Pharmacological Assessment

In this study, we investigated whether tacrolimus extracted and purified from the commercial capsules (Prograf® 5 mg) have retained its original quality and activity beyond the capsules expiration date in order to be reused for research purposes after extraction. High-performance liquid chromatography (HPLC) assay method was developed and validated for the quantification of tacrolimus, using cyclosporine A as an internal standard (IS). Moreover, a combination of analytical methods, including nuclear magnetic resonance (NMR), gas chromatography-mass spectrometry (GC-MS), Fourier transform-infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), and differential scanning calorimetry (DSC) were used to assess the quality of extracted/purified tacrolimus. Suppression of murine peripheral-blood mononuclear cells (PBMC) proliferation and the levels of interleukin-2 (IL-2) and interferon gamma (IFN-γ) were also assessed. The data obtained showed no detectable differences in the quality profile between the authentic sample and extracted drug. Also, the results showed that the extracted/purified tacrolimus was able to suppress T cell proliferation, induced by concanavalin A, indicating the retained pharmacological activity. We proved that tacrolimus extracted/purified from expired Prograf® capsuled retains its purity and immunosuppressive activity and can be reused for research and possibly in pharmaceutical manufacturing.

Application of Concanavalin A during immune responsiveness skin-swelling tests facilitates measurement interpretation in mammalian ecology

The skin‐swelling test is a simple and widespread method used in field ecological research to estimate cellular immune responsiveness in animals. This immunoecological test is based on measuring the magnitude of tissue swelling response at specific times following subcutaneous application of an experimental pro‐inflammatory stimulant. In the vast majority of studies across vertebrate taxa, phytohemagglutinin (PHA) is used as a universal stimulant. Given the complexity of immune response activation pathways of PHA, however, interpretation of test results can be ambiguous. Goal of this study was to improve methodology of the skin‐swelling test to decrease this ambiguity. Here, we present an alternative protocol aimed at facilitating interpretation of skin‐swelling data for mammals. Based on previous evidence suggesting that mammalian T cells are readily activated by Concanavalin A (ConA) in vitro, we compared cellular immune responses in vivo to PHA and ConA as an alternative pro‐inflammatory stimulant in mice. We measured magnitude of tissue swelling and compared it with intensity of blood cell infiltration into tissue over a 72‐hour interval. Our results corroborate that PHA and ConA show important differences in both dynamics and response amplitude in rodents. ConA induces stronger swelling with a distinct leukocyte activity pattern and higher pro‐inflammatory cytokine (interleukin 6 [IL‐6] and interferon gamma[IFN‐γ]) expression than PHA during peak response (24‐h post‐treatment). Furthermore, unlike PHA, magnitude of swelling was positively associated with cellular activity (number of neutrophils infiltrating tissue) following ConA injection. We conclude that ConA is the more suitable stimulant for skin‐swelling tests in mammals. This is because of the molecular binding specificity in the two lectins, that is, ConA specifically activates T cells while PHA also triggers erythroagglutination. We propose that ConA be used in all future ecological testing in mammals as it exhibits better performance and its application facilitates immunological interpretation of skin‐swelling test results.

Biological expressions of lymphocyte activation : I. Effects of phytomitogens on antibody synthesis in vitro

The effects of nonspecific phytomitogens on primary plaque-forming cell (PFC) responses of mouse spleen cells to heterologous erythrocytes in vitro were studied. Spleen cell cultures treated with concanavalin A or phytohemagglutinin in vitro or established with spleen cells derived from mice injected with concanavalin A 24 h previously were similarly affected. In both cases, submitogenic doses resulted in substantial enhancement of PFC responses, whereas 10-fold larger doses were profoundly inhibitory. In contrast to the suppressive effects of mitogenic doses of phytomitogens added at culture initiation, addition of these same doses to cultures 48 h later resulted in increased PFC responses. This enhancement could be observed within 1 h after treatment and consequently could not be ascribed only to mitotic expansion of the antibody-synthesizing clone. Activation of spleen cells with specific antigen before mitogen treatment was not required for expression of the enhancing or suppressing effects on PFC responses. IgM and IgG PFC responses were similarly affected. Studies of cell interactions revealed that as few as 10⁵ spleen cells obtained from mice treated with concanavalin A in vivo synergistically enhanced the PFC responses of 10⁷ normal spleen cells. This enhancement was mediated by mitogen-activated T lymphocytes which were resistant to 2000 R irradiation 24 h after activation. The relevance of these observations to emerging concepts of helper and suppressor T cell activity is discussed.

Cellular immune responses and cytokine production in BALB/c and C57BL/6 mice during the acute phase of Angiostrongylus costaricensis infection

In our experimental study we were able to show that the contrasting outcome of Angiostrongylus costaricensis infection in C57BL/6 and BALB/c mice, in respect of morbidity and mortality, can be explained by divergent cellular immune responses and a different cytokine pattern in each strain. In BALB/c mice (i.e. those with high mortality), the initial high proliferation of ConA or LPS stimulated spleen cells dropped to very low levels after 2 weeks post-infection (p.i.), whereas in C57BL/6 mice (i.e. those with low mortality), only a minor reduction in lymphoproliferative responses after mitogenic stimulation was observed. The specific proliferation of spleen cells after stimulation with A. costaricensis adult worm antigen remained low in BALB/c mice throughout the experiment, but showed an augmented proliferation in C57BL/6 mice, especially from 2 weeks p.i. onwards. The mitogen-induced production of Th2-type cytokines (IL-4, IL-5, IL-6, IL-10) in spleen cell cultures remained low in BALB/c mice until 4 weeks p.i., but production of Th1-type cytokines (IL-2, IFN-gamma) was highly elevated at 14 and 28 days p.i. In C57BL/6 mice, an upregulated and balanced production of both Th1- and Th2-type cytokines was measured during the course of infection. In summary, a polarization of the immune response towards cellular hyporesponsiveness and a predominantly Th1 cytokine profile was observed in A. costaricensis infected BALB/c mice, which may contribute to pathogenesis and increased morbidity.

Mitogenic effect of zinc on lymphocytes from strains of mice that are either high or low-responder to T-cell mitogens

We have studied the in vitro mitogenic effect of ZnCl2 in cultures of lymphocytes from Balb/c or C57BL/6 mice which are high-responder or low-responder to T-cell mitogens respectively. Zn induced proliferation of spleen cells from Balb/c mice cultured without 2-ME. Higher levels of proliferation were observed in cultures with 2-ME. In contrast, Zn only induced proliferation of spleen cells from C57BL/6 mice in the presence of 2-ME. No response to Zn was observed in cultures without 2-ME, of spleen cells from either Balb/c or C57BL/6 mice depleted of plastic adherent cells. However, in cultures with 2-ME, Zn induced proliferation of non-adherent as well as plastic adherent cells from either strain of mice. In cultures without 2-ME, Zn induced proliferation of thymocytes from Balb/c mice, whereas did not show constant mitogenic effect on thymocytes from C57BL/6 mice. In contrast, Zn determined higher levels of proliferation of thymocytes from either strain of mice when cultured with 2-ME. Zn had earlier and stronger mitogenic effect on mature thymocytes of either strain of mice than in total thymocytes, both in cultures with or without 2-ME. However, Zn did not induced proliferation in cultures of immature thymocytes of either strain of mice.

Ontogeny of T cell development in avian scleroderma

UCD line 200 chickens develop an inherited fibrotic disease associated with the production of antinuclear antibodies, antibodies to type II collagen, and early skin lesions characterized by intense T lymphocyte infiltrates. In the present study we have investigated the hypothesis that developmental abnormalities in T lymphocyte differentiation predispose the line 200 chickens to autoimmune disease. The status of the thymic microenvironment in these birds during ontogeny was studied with an extensive panel of monoclonal antibodies (mAbs) reactive with distinct stromal cell subsets including MHC determinants. In addition, their T-cell graft-versus-host reactivity and responses to mitogenic stimulation and interleukin (IL)-2 were also analyzed. Line 200 chickens have profound defects in thymic structure with a virtual complete absence of antigens specific for type I epithelium which lines the thymic subcapsular and perivascular regions. There are excessive levels of MHC class II positive cells, particularly in the cortex, and B cells/subset macrophages identified by mAb MUI 36. These defects are found from the late embryonic period, long before clinical disease is manifest. Furthermore, by FACS analysis, line 200 thymocytes have a major increase in IL-2 receptor density. In addition, line 200 chicken peripheral blood lymphocytes (PBL) respond poorly to mitogenic agents and have a reduced response to IL-2. Finally, it is important to note that line 200 PBL produce a normal graft-versus-host reaction. We propose that these abnormalities in T-cell differentiation are selective, not global, and may be reflective of a defect in thymic education resulting in an inappropriate response to self-antigens.

In vitro proliferation of murine spleen cells: genetic control of proliferative responses induced by phorbol ester and calcium ionophore A23187

Proliferative responses of normal (not immunized intentionally) spleen cells from inbred strains of mice to co-stimulation with phorbol ester (PMA) and calcium ionophore A23187 were studied. Striking differences in the magnitude of the responses of spleen cells and splenic T cells from various strains were observed. It appeared that these differences reflected mainly differences in the inducibility of the expression of the gene for the alpha chain of the IL2 receptor (IL2R) by phorbol ester. Formal genetic analysis suggested that the differences in response to phorbol ester and calcium ionophore are controlled by two independent genes with the alleles controlling good response being dominant. The differences in the inducibility of the IL2R gene seemed to be controlled by alleles of a single gene. At least one of the putative genes may be a regulatory element affecting the gene for the alpha chain of IL 2R. The results may have a practical significance for devising more efficient procedure(s) to generate LAK cells used for tumor immunotherapy.

In vitro O2-induced depression of T and B lymphocyte activation is reversed by diethyldithiocarbamate (DDC) treatment

In this study, we tried to establish a relationship between the immunopotentiating effects and the antioxidant activity of the immunostimulating compound, diethyldithiocarbamate (DDC). We studied the effects of DDC treatment on enriched T and B murine spleen lymphocytes in an in vivo-ex vivo model of O2-induced immune depression. Female C57B1/6 mice were injected subcutaneously with a single dose of DDC (125 mg.kg-1). Eight days after DDC injection, we evaluated, in vitro, the concanavalin A response of the T cell fraction and the LPS response of the B cell fraction, under standard (air--5% CO2) and hyperoxic (60% O2--5% CO2) culture conditions. The results show that after a lag period, DDC is able to enhance the mitogenic response of T and B murine lymphocytes under standard culture conditions to restore the ConA response and to partially restore the LPS response under hyperoxic conditions. The results of this study suggest that the immunostimulatory effects of DDC could be related to the antioxidant activity of this compound on the lymphoid cellular metabolism. This activity apparently affects both T and B lymphocytes.

Influence of the Hal locus and standardized stress on antibody response and in vitro reactivity of peripheral blood lymphocytes in pigs

The antibody response to two Escherichia coli antigens (O149 and K88) and the in vitro reactivity of peripheral blood lymphocytes (PBLs) to pokeweed mitogen was studied in growing pigs after exposure to varying degrees of stress. Three experimental groups were used; transportation by lorry, transportation by lorry after a previous injection of a tranquillizing drug (amperozide), no transportation but an amperozide injection. Another group was used as a control group. This group was not transported and received no amperozide injection. The animals were the offspring of boars and sows heterozygous (Nn) for the Hal gene, and all 3 Hal genotypes (NN, Nn, nn) were identified and could thus be compared within litters. Immediately after the experimental treatment, the highest PBL reactivity was found for the amperozide-treated animals and for the non-transported animals, with no differences in reactivity between Hal genotypes. Two weeks later, the treatments caused different effects on pigs of the 3 Hal genotypes, both with regard to the PBL reactivity and the IgG response to O149. The NN pigs had a higher PBL reactivity than the nn pigs for all treatments except the 'drug + transport' class where the reverse rank order was found. The NN pigs also had a higher IgG response to O149 than the nn pigs in the 'drug + no transport' class. The amperozide treatment was followed by a higher PBL reactivity in non-transported NN pigs and in transported nn pigs. The amperozide-treated non-transported NN pigs also had a higher IgG response to O149. The highest PBL reactivity and IgG response to O149 were found mainly in pigs with the lowest cortisol levels. Pronounced differences between litters were found for both the antibody response and the PBL reactivity.

Differences in the effect of indomethacin and preincubation on the lymphoproliferative response to concanavalin A of spleen cells from low responder C57BL/6 and high responder BALB/c mice

In vivo treatment with 100 micrograms of indomethacin each 48 h for 2 weeks enhanced the proliferative response to concanavalin A (Con A) of spleen cells from mice of the C57BL/6 (B6) strain, low responder to T cell mitogens, but did not modify the response of spleen cells from mice of the high responder strain BALB/c (C). The enhancing effect of in vivo indomethacin treatment was more marked in cultures of B6 splenocytes stimulated with high, moderately supraoptimal doses of Con A than in cultures stimulated with optimal mitogen doses. Addition of indomethacin to cultures of spleen cells from untreated donors induced greater increase of the lymphoproliferative response of cells from low responder B6 than from high responder C mice. The enhancing effect of indomethacin added in vitro was observed in cultures stimulated by optimal but not by supraoptimal doses of Con A. The addition of indomethacin did not enhance the response of B6 spleen lymphocytes depleted of adherent cells. Preincubation for 24 h prior to mitogen stimulation increased the response to high Con A doses of spleen cells from low responder B6 mice whereas this procedure did not enhance lymphocyte proliferation in cultures of spleen cells from high responder C mice. Supplementation with indomethacin in vitro combined with preincubation induced additive enhancing effects on DNA synthesis by B6 spleen lymphocytes, suggesting that each treatment acts through different mechanism(s). The results indicated that spleen cells from low responder B6 strain mice are more sensitive than cells from high responder C mice to the potentiating effect of indomethacin and preincubation on the proliferative response to Con A. These observations suggest that mechanisms sensitive to indomethacin and to preincubation contribute to the depression of mitogen induced DNA synthesis in low responder B6 mice.

Modulatory effect of zinc on the proliferative response of murine spleen cells to polyclonal T cell mitogens

To study the effect of zinc on the proliferative response to polyclonal T cell mitogens, spleen cells from C57BL/6 mice were cultured with or without ZnCl2 and stimulated with graded doses of concanavalin A or phytohemagglutinin. Addition of 10(-4) M ZnCl2 inhibited proliferation whereas 10(-5) to 10(-6) M ZnCl2 did not modify the response to suboptimal doses of mitogen but increased DNA synthesis in cultures stimulated with high doses of mitogen (10 or 20 micrograms/ml of concanavalin A and 10 or 25 microliters/ml of phytohemagglutinin) which are supraoptimal for C57BL/6 mice, and inhibited proliferation in cultures of spleen cells from animals of this strain, low responder to T cell mitogens. In contrast, supplementation with ZnCl2 did not enhance the response to mitogen of spleen cells from high responder BALB/c mice. The enhancing effects of ZnCl2 on the proliferative response of C57BL/6 cells were not observed following depletion of adherent cells or in cultures supplemented with 5 X 10(-5) M 2-mercaptoethanol, both conditions capable of abrogating the inhibitory effect of high mitogen doses on the response of C57BL/6 cells.

Cellular aspects of genetic defects in Con A mitogenesis

The cellular basis for genetically determined low Con A stimulation of peripheral blood lymphocytes from two inbred lines of chickens was investigated. A simple shift in the dose-response curve was not responsible for the low stimulation. In addition, proliferation was neither accelerated nor delayed. The results of mitogen and cell mixing experiments showed that the low Con A stimulation in both strains was not mediated by suppression. Furthermore, cocultures of lymphocytes from the two low Con A responder lines complemented to give high Con A stimulation. These results indicate that at least two distinct genes, apparently expressed in different cell populations, can confer low Con A responses in chickens.

HLA and T-lymphocyte function in old age

The role of the major histocompatibility complex in the genetic control of reactivity of peripheral blood mononuclear cells (T lymphocytes) to lectins and allogeneic cells as a function of age was investigated. In randomly selected aged subjects the frequencies of HLA-A, B, and some C locus alleles did not differ significantly from those in the control group. However, some tendencies of haplotype frequency differences between young and aged subjects were found. Significant associations of impaired or preserved T-lymphocyte function could be detected in connection with some HLA-A (A3, A11) antigens only. The tendency of some phenotypic HLA-A and B or C and B antigen associations to be in correlation with impaired or preserved T-lymphocyte reactivity in old age seemed to be independent of their age-related frequency differences. In family studies of a partially inbred Hungarian population, differences were found in the rate of diminution of allogeneic reactivity in groups sharing different HLA haplotypes. Based on statistical analysis of these data, a genetic factor segregating with the MHC and taking part in the regulation of the age-dependent decline of T-lymphocyte reactivity can be postulated.

Genetic control of the response of chicken T lymphocytes to concanavalin A: cellular localization of the low responder defect

Genetic variation in the response of chicken lymphocytes to the T cell mitogen concanavalin A (Con A) has previously been studied by assaying tritiated thymidine [( 3H]dThd) uptake of cultured cells following mitogen stimulation. Our present results show, firstly, that low [3H]dThd uptake (e.g. in cultures of Con A-stimulated cells from low responder CB, CC or G-B1-lo birds) is correlated with low proliferative activity and with reduced capacity to form Con A-dependent T cell colonies in semi-solid agar. Secondly, in cultures containing mixtures of cells from high and low responder birds, the cells from each partner respond independently to Con A (there is neither suppression of high responder, nor activation of low responder cell proliferation). Finally, Con A-stimulated cultures of high responder cells respond better to T cell growth factors, as well as producing more growth factor activity, than cultures of low responder cells. These results suggest that the basis for the low responder phenotype is an intrinsic inability of low responder T lymphocytes to respond to Con A by differentiating into growth factor-sensitive blast cells.

In vitro viability of lymphoid cells from lines of mice genetically selected for high or low responsiveness to phytohemagglutinin

The kinetics of viability of lymph node and spleen cells of mice genetically selected for "high" or "low" in vitro lymphocyte responsiveness to PHA were studied in PHA or PPD-stimulated short-term cultures. Lo/PHA cells were found to be less viable than Hi/PHA cells in unstimulated control cultures. PHA improved the viability of Lo/PHA cells while inducing proliferation of Hi/PHA cells with the appearance of more and larger lymphoblasts in the latter. PPD only improved the viability of spleen cell cultures, more so for the Hi/PHA line. The interline difference in thymidine uptake was smaller after PPD than after PHA stimulation. Modifications of culture conditions designed to decrease the interline difference in cell viability lessened but did not abolish the separation between the two lines for the PHA response as measured by thymidine uptake.

H2 gene control and biological activities of a T-cell mitogen derived from Mycoplasma arthritidis: a review

Mycoplasma arthritidis generates a soluble, non-dialysable, polyclonal mitogen which is active for murine and human T lymphocytes in the presence of an adherent, radio-resistant, Ia-bearing accessory cell population. Genetic analysis has established that the I-E sub-region of the murine H2 gene complex controls responses to the mitogen and that this control is exercised at the level of the Ia-bearing accessory cell. Lymphocyte proliferation, induction of cytotoxic lymphocytes, and interferon induction are all under Ir gene control and appear to be dependent upon binding of the mitogen to a specific Ia antigen present on a subset of splenic cells. This mycoplasma mitogen provides a new model system to define the mechanisms of Ir gene control of lymphocyte activation.

Blood T-lymphocyte functions in healthy adults in relation to age

Blood T-lymphocyte functions were studied in 167 healthy adults (age range 19-91 years). Lymphocyte DNA synthesis induced by concanavalin A, pokeweed mitogen and PPD antigen declined with age while the spontaneous DNA synthesis remained essentially unchanged. Relative and total T-cell counts but not total lymphocyte counts were moderately decreased in elderly persons. The lymphocyte response to mitogens correlated with the PPD-induced activation in vitro. Lymphocyte and T-cell counts did not show any association with the response to mitogens and antigen. A few subjects were tested on several occasions during 2-7 years confirming a good reproducibility of the techniques employed. Thus ageing is associated with diminished number of T-cells and impairment of lymphocyte activation by T-cell mitogens and PPD antigen. The clinical importance of this general age-related T-cell deficiency remains largely unresolved.

Genetic control of T-lymphocyte mitogenesis in chickens

The in vitro mitogenic response to PHA and Con A was determined in three inbred lines of chickens. Lymphocytes from one line consistently showed a greater stimulation by PHA than the other two lines. Analysis of F1 crosses and backcrosses indicated that this quantitative difference was controlled by more than one gene. More substantial differences in Con-A stimulation were also observed between the three lines, and the data indicated that separate genetic systems were controlling the variation in PHA and Con-A stimulation. Analysis of F1 crosses, backcrosses and assortative matings between backcrosses revealed that the variation in Con-A stimulation was controlled by at least two major genes, one of which may be linked to the major histocompatibility complex. Surprisingly, one line appeared to be segregating for Con-A stimulation in spite of an inbreeding coefficient greater than 0.98.

Cellular immunity in aging

Our study of the aging process in human beings and in mice is complicated by our need to know whether we are observing diseases of aging or natural nondisease state processes. Results from studies on inbred strains of mice and retrospective studies on HLA types in aging human populations suggest that genetic effects play a significant role in predetermining the life span of an individual. It is clear that in such mouse strains genetic defects that affect cell regulatory mechanisms result in the production of autoimmune reactivity, tumor development, and a shortened life span. In human beings, although results are less clear-cut, strong associations exist between some disease states and the HLA type. Also, the disappearance of HLA-B8 from older women suggests that this HLA type does not confer longevity. Cellular immune reactivity declines with age in all populations studied to date, and cell cooperative or regulatory mechanisms function less well. We need to characterize the specific nature of the cells directly responsible for these alterations and to attempt to correct deficiencies by dietary manipulation or transfer techniques.

Differences in [3H]-thymidine uptake of lymph node cells stimulated by Con A and PHA in H-2 congenic mouse strains

The genetic control of the lymphocyte responsiveness to Con A and PHA-P has been studied by using inbred, H-2 congenic mouse strains. Segregation studies were carried out on F1 and backcross mice of a high and a low responder strain. According to the results, there is a strong correlation between the responsiveness of lymph node cells to mitogens and H-2 haplotypes in different H-2 congenic strains of mice and in different backcross generations. High responsiveness to PHA-P is associated with H-2b, while low responsiveness with H-2a or H-2k haplotypes, but the correlation is the inverse in response to Con A, in the parental strains and backcross mice as well. The magnitude of the responses to both Con A and PHA-P was found to be intermediate in F1 heterozygotes of a low and high responder parental strain. The effect of other non H-2 genes on the responsiveness to these mitogens has also been demonstrated.

Separation of T and B lymphocytes from various mouse strains by density gradient electrophoresis

T and B mouse spleen lymphocytes were separated by density gradient electrophoresis on the basis of their surface charge. In all strains examined, the T lymphocytes were found in the high mobility fractions and the B in the low. The T and B cells were separated completely in most fractions, with some overlapping in the middle. Significant differences were found in the electrophoretic distribution profiles between the strains: C57BL/6j, C57BL/10j, (BALB/cXC57BL/6j)F1, and all the following: B6.C-H-2d/cBy (congenic to C57BL/6j), BALB/c, CBA/H/T6j, C57BL/10Sn, and C3H. The C57BL/6j and the (BALB/cXC57BL/6j)F1 cells appear more heterogeneous as far as electrophoretic mobility is concerned. Almost all the other strains give two major peaks. Moreover, the high mobility areas are less populated in the C57BL/6j and the (BALB/cXC57BL/6j)F1 animals than in all the others. The above differences were found consistently when cells prepared by different methods were electrophoresed. It is concluded that the surface charge of lymphocytes may be genetically determined. Possible dependency on the H-2 complex or non-H-2 areas is discussed.

Influence of supernatants from polymorphonuclear leucocytes on blastogenesis of syngeneic and allogeneic murine splenocytes

Supernatant was produced from activated peritoneal polymorphonuclear leucocyte-rich cell populations from different strains of mice. These supernatants were studied for their ability to modify spontaneous and mitogen-induced blastogenesis of syngeneic and allogeneic splenocytes. Our results indicate that polymorphonuclear leucocyte-rich cell cultures from two strains of mice, A/J and BALB/c, produced a supernatant that could enhance PHA-induced blastogenesis of syngeneic and allogeneic splenocytes. Cells from a third strain C57B1/6, did not produce an active supernatant. In general, the response by splenocytes from these three strains paralleled the production of active supernatant that we observed. The response to the active supernatant was dependent upon the mitogen stimulation of the splenocytes, the mitogen dilution and the supernatant activity. These functions are believed to be genetically determined.

Genetic differences in the mitogenic response of peripheral blood lymphocytes in the chicken

The mitogenic responses of chicken peripheral blood lymphocytes were compared in two partially inbred chicken lines and in their hybrids. The lymphocytes of line P chickens showed a higher phytohaemagglutinin (PHA) response than those of line V chickens and (P X V)F1 hybrids. The Con A responses were of the same magnitude in all chicken lines. The higher PHA response in line P chickens was not sex-linked, apparently was not associated with the major histocompatibility complex and it did not correlate with immunoglobulin G allotypes.

Immunological defects in healthy twin siblings to patients with Hodgkin's disease

We studied the immunocompetence of 6 healthy twins, whose monozygotic or dizygotic same-sexed twin partner had died from Hodgkin's disease. Lymphocyte DNA synthesis induced by concanavalin A was markedly reduced at 3 different concentrations in all twins compared to an age-matched group of healthy controls. The lymphocyte response to pokeweed mitogen and to phytohaemagglutinin was also impaired. PPD induced lymphocyte DNA synthesis was low in 3 twins and correlated well with their delayed skin hypersensitivity to the antigen. One twin was completely anergic to 3 different skin antigens. The mean total blood lymphocyte count did not differ from that of controls. There was no change in T or B-lymphocyte subpopulations. The presence of a functional lymphocyte deficiency in all twins strongly suggests that the immunodeficiency in Hodgkin's disease is partly caused by genetic and/or environmental factors.

Genetic selection of mice for quantitative responsiveness of lymphocytes to phytohemagglutinin

A two-way selection was performed in mice according to the quantitative in vitro response of lymph node lymphocytes to the mitogenic activity of phytohemagglutinin (PHA). The foundation population was composed of outbred mice produced by reciprocal mating of equal numbers of mice from four different colonies. The selective breeding was carried out by mating of mice at each generation giving the best or the lowest response, respectively. The progressive interline separation produced by 6 generations of selective breeding demonstrates that responsiveness to PHA is submitted to polygenic regulation. The heritability of the character investigated is 0.28 +/- 0.08. The interline separation is also found with another T mitogen, concanavalin A (Con A). In spleen cells PHA and Con A produce a similar interline difference. In contrast, the purified protein derivative of tuberculin (PPD) stimulated both lines equally, and E. coli lipopolysaccharide gave only a slightly higher response in high line. This finding implies that our selection based upon response to PHA did not influence B cell function.

The genetic control of the antibody response in inbred rats

The antibody response of genetically inbred rats to poly(Glu52Lys33Tyr15) is controlled by a complex polygenic system which includes at least two autosomal genes and a sex influence, which may also be genetically determined. The genetic control of the quantity, binding constants, and specificity of the antibody formed linked to the major histocompatibility locus. Factors other than the major genetic ones and the sex influence also affect the quantity of antibody formed, since animals of the same genotype can make significantly different amounts of antibody, depending upon the crosses by which they acquire the major histocompatibility alleles. After immunization with poly(Glu52Lys33Tyr15) the low responders make fewer antibody-producing cells, are not capable of mounting a delayed hypersensitivity reaction to the polypeptide and appear to be deficient in their ability to produce the specific IgM antibody. Immunization of the low responders with antigen aggregated with methylated bovine serum albumin enhances the quantity of antibody formed, increases the binding constants and crossreactivity of the antibody and enhances the delayed hypersensitivity response. In contrast to the findings with the L-amino acid polypeptide, there does not appear to be any genetic control over the antibody response to the D-amino acid enantiomorph poly(DGlu52DLys33DTyr15), which is minimal in all strains.

Genetic control of the in vitro responses of rat blood lymphocytes. I. Comparison of in vitro and in vivo responses

Nielsen, H. E. & Koch, C. Genetic Control of the In Vitro Responses of Rat Blood Lymphocytes. I. Comparison of In Vitro and In Vivo Responses, Scand. J. Immunol. 4, 31-36, 1975. In vitro DNA synthetic responses of blood lymphocytes from the inbred rat strains BN, Lewis, and AS were compared with each other after stimulation with allogeneic lymphocytes, human lymphocytes, phytohemagglutinin, and anti-Ig antibodies. BN lymphocytes responded less well than AS and Lewis lymphocytes regardless of the stimulus used. The responses of the congenic strains Lewis and Lewis. BN were identical, suggesting that H-1 (Ag-B)-linked loci do not determine in vitro responsiveness in these strains. In vivo, AS and BN rats were equally able to reject third-party skin grafts and to induce graft-versus-host reactions in F1 hybrids. We conclude that the interstrain differences found in vitro reflect genetically determined differences in in vitro kinetics, possibly related to the fraction of short-lived lymphocytes present rather than to demonstrable differences in the frequency of reactive lymphocytes.

Cell-mediated immune responses in vitro. I. Suppression of the generation of cytotoxic lymphocytes by concanavalin A and concanavalin A-activated spleen cells

The effects of soluble concanavalin A (Con A) or Con A-activated spleen cells on the generation of cytotoxic lymphocytes (CL) in mixed leukocyte cultures (MLC) were examined. Mitogenic concentrations of soluble Con A or small numbers of Con A-activated spleen cells substantially inhibited CL responses. The suppression was partial rather than absolute and was critically dependent upon the concentration and time of addition of soluble Con A or Con A-activated spleen cells to the MLC. Suppressive effects of Con-A activated spleen cells were mediated by T cells since suppressor cell activity was abrogated by treatment of spleen cells with anti-theta serum and complement before or after Con A activation. X irradiation of spleen cells before Con A treatment also abrogated generation of suppressor cell activity. After activation by Con A, however, the function of suppressor cells was radioresistant. Although the precise mechanism(s) of suppression is, as yet, unknown, the precursors of CL must be exposed to Con A-activated cells during the early phases of the immune response for suppression to occur. Kinetic studies revealed that suppression of CL responses was not due to a failure to initiate an immune response, but represented a response which developed initially, but subsequently aborted. The relevance of these observations to the concepts of T-cell-T-cell interaction and regulatory control of immune responses by T cells is discussed.