Syngeneic responses by murine thymocytes: a role for non-MHC and non-MLS genes

A subpopulation of thymocytes from adult mice that is nonadherent to macrophage monolayers showed dramatically increased syngeneic mixed leukocyte responses (SMLR). Cloned cells were derived by limiting dilution from these SMLR-primed BALB/c thymocytes and were maintained and subcloned by repeated stimulation with syngeneic BALB/c spleen cells without the addition of exogenous interleukins. The cloned thymocytes were tested for their reactivities against H-2- and Mls-identical BALB/c and B10.D2 spleen cells (H-2d, Mlsb). We found that BALB/c and B10.D2 stimulator cells differed significantly in their capacity to restimulate the cloned BALB/c thymocytes. In addition, polyclonal syngeneic mixed leukocyte cultures (SMLC) of BALB/c thymocytes also showed differential restimulation by BALB/c and B10.D2 stimulators. Taken together, our data indicate a role for the product(s) specified by non-MHC and non-Mls gene(s) in the autorecognition by thymocytes.

Syngeneic responses by murine thymocytes: a role for non-MHC and non-MLS genes

A subpopulation of thymocytes from adult mice that is nonadherent to macrophage monolayers showed dramatically increased syngeneic mixed leukocyte responses (SMLR). Cloned cells were derived by limiting dilution from these SMLR-primed BALB/c thymocytes and were maintained and subcloned by repeated stimulation with syngeneic BALB/c spleen cells without the addition of exogenous interleukins. The cloned thymocytes were tested for their reactivities against H-2- and Mls-identical BALB/c and B10.D2 spleen cells (H-2d, Mlsb). We found that BALB/c and B10.D2 stimulator cells differed significantly in their capacity to restimulate the cloned BALB/c thymocytes. In addition, polyclonal syngeneic mixed leukocyte cultures (SMLC) of BALB/c thymocytes also showed differential restimulation by BALB/c and B10.D2 stimulators. Taken together, our data indicate a role for the product(s) specified by non-MHC and non-Mls gene(s) in the autorecognition by thymocytes.

Studies on derivatives of 2,3-dihydro-4H-1,3,2-benzoxazaphosphorine. Synthesis and structure analysis of 2,3-disubstituted-2,3-dihydro-4H-1,3,2-benzoxazaphosphorin-4-one -(thio ne)-2-sulfide(oxide)

A series of novel organocyclophosphorus compounds including twenty-three 2,3-disubstituted-2,3-dihydro-4H-1,3,2-benzoxazaphosphorin-4-one-2 -sulfide (compounds I) and three 2,3-disubstituted-2,3-dihydro-4H-1,3,2-benzoxazaphosphorin-4-th ion e-2-oxide (compounds II) have been synthesized. Their structures were determined by IR, UV, 1HNMR, X-ray diffraction and elemental analysis. Each of compounds I showed a strong absorption between 1290-1319 cm-1 in the IR spectrum. Comprehensive studies of the spectral data and experimental results indicated that this strong characteristic absorption is different from that of the P = O linkage and thus could be considered as a result of the stretching vibration of (unsaturated C)-N single bond. In the course of synthesis of the compounds, an abnormal product (Formula: see text) is frequently formed as an isomer of the expected product I (Formula: see text). However, by suitable choice of condensation conditions, either of the isomers could be made predominantly in yield and be readily isolated from the other by recrystallizing for several times from appropriate solvent. Data for the melting point, IR, UV and 1HNMR spectra of three pairs of the isomers are given, and primary analyses of the spectra are made as well.

Thymocyte and macrophage interactions: separation of murine thymocyte subsets and enrichment of syngeneic cell-responding thymocytes by adsorption to macrophage monolayers

The spontaneous binding of murine thymocytes to macrophage monolayers was employed to separate thymocytes into macrophage-unbound and -bound subsets, and the functional reactivities of these two subpopulations were examined. Macrophage-unbound thymocytes were found to be enriched in functional subsets reactive to semi-allogeneic and allogeneic stimulating spleen cells by proliferation in mixed leukocyte culture (MLC). Furthermore, macrophage-unbound thymocytes were frequently found to respond to syngeneic spleen cells. This syngeneic proliferative response showed both memory and specificity upon subsequent restimulation and thus seems to represent a syngeneic mixed leukocyte reaction (SMLR). Syngeneic responding thymocytes were also found to produce interleukin 2 when cultured with syngeneic but not allogeneic stimulator cells. In contrast, macrophage-bound thymocytes showed greatly reduced proliferative responses to allogeneic stimulators and no responses to syngeneic stimulators. The macrophage-bound thymocyte subset was not enriched in detectable suppressive activity; proliferative responses of macrophage-unbound thymocytes to either allogeneic or syngeneic cells were neither suppressed nor enhanced when macrophage-unbound thymocytes were added to the cultures. Thus, the macrophage-unbound subset seems to be enriched in functionally mature thymocytes and the macrophage-bound subset appears to be enriched in functionally immature thymocytes. This functional separation of thymocytes by macrophage adherence also correlated well with thymocyte subpopulations separated by bovine serum albumin density gradients; the low density mature thymocytes showed enhanced responses to both allogeneic and syngeneic stimulators, whereas the high density immature cells were unresponsive. This correlation was supported further by binding studies in which T cell tumor lines derived from C57BL/6 mice were used. ERLD tumor cells, which are similar to cortical immature thymocytes in both enzymatic and surface antigenic markers, were found to bind readily to macrophages, whereas both EL-4 and E male G2 tumor cells, with characteristics of mature thymocytes, bound to macrophages poorly. The binding of thymocytes and ERLD tumor cells to macrophages was not genetically restricted. We speculate that thymocyte binding to macrophages may play a critical role during the functional maturation of thymocytes.

Thymocyte and macrophage interactions: separation of murine thymocyte subsets and enrichment of syngeneic cell-responding thymocytes by adsorption to macrophage monolayers

The spontaneous binding of murine thymocytes to macrophage monolayers was employed to separate thymocytes into macrophage-unbound and -bound subsets, and the functional reactivities of these two subpopulations were examined. Macrophage-unbound thymocytes were found to be enriched in functional subsets reactive to semi-allogeneic and allogeneic stimulating spleen cells by proliferation in mixed leukocyte culture (MLC). Furthermore, macrophage-unbound thymocytes were frequently found to respond to syngeneic spleen cells. This syngeneic proliferative response showed both memory and specificity upon subsequent restimulation and thus seems to represent a syngeneic mixed leukocyte reaction (SMLR). Syngeneic responding thymocytes were also found to produce interleukin 2 when cultured with syngeneic but not allogeneic stimulator cells. In contrast, macrophage-bound thymocytes showed greatly reduced proliferative responses to allogeneic stimulators and no responses to syngeneic stimulators. The macrophage-bound thymocyte subset was not enriched in detectable suppressive activity; proliferative responses of macrophage-unbound thymocytes to either allogeneic or syngeneic cells were neither suppressed nor enhanced when macrophage-unbound thymocytes were added to the cultures. Thus, the macrophage-unbound subset seems to be enriched in functionally mature thymocytes and the macrophage-bound subset appears to be enriched in functionally immature thymocytes. This functional separation of thymocytes by macrophage adherence also correlated well with thymocyte subpopulations separated by bovine serum albumin density gradients; the low density mature thymocytes showed enhanced responses to both allogeneic and syngeneic stimulators, whereas the high density immature cells were unresponsive. This correlation was supported further by binding studies in which T cell tumor lines derived from C57BL/6 mice were used. ERLD tumor cells, which are similar to cortical immature thymocytes in both enzymatic and surface antigenic markers, were found to bind readily to macrophages, whereas both EL-4 and E male G2 tumor cells, with characteristics of mature thymocytes, bound to macrophages poorly. The binding of thymocytes and ERLD tumor cells to macrophages was not genetically restricted. We speculate that thymocyte binding to macrophages may play a critical role during the functional maturation of thymocytes.

Managing families of the demented elderly

Dementing illness affects about 10 percent of people over 65 years of age, and families encounter many problems as they attempt to care for these relatives. Physicians can assist in several ways, beginning with establishing an accurate diagnosis, as terms such as "senility," "dementia," and "hardening of the arteries" are imprecise and may convey an attitude of hopelessness. A psychiatric, medical, and laboratory evaluation usually leads to a specific diagnosis. About one half of all cases are due to Alzheimer's disease, but there is frequently a treatable component to the demented patient's condition. In addition to making an accurate diagnosis and treating reversible problems, physicians can assist the family in having the patient do all he or she is capable of including increasing specific activities, can help the family understand that even their best efforts may not lead to improvement, can point out ways for the family to balance the patient's needs with their own, and can teach the family how to communicate more effectively with the patient.

Cognitive correlates of diffuse cerebral atrophy determined by computed tomography

The relationship between severity of diffuse cerebral atrophy determined by computed tomography (CT) and severity of cognitive impairment was examined in 55 men, 50 to 77 years old. Partial correlations, controlling for the effects of age and education, indicated that increased cerebral atrophy was associated with decline in orientation, recent memory, and general level of intellectual functioning. Correlations between degree of atrophy and decline in immediate and remote memory were not significant. Despite significant associations between cerebral atrophy and some aspects of intellectual functioning, considerable variance in performance on cognitive tasks was not explained by cerebral atrophy. Therefore, the degree of diffuse cortical and central atrophy observed on CT scan did not closely predict the degree of cognitive dysfunction, nor did the observation of cerebral atrophy necessarily indicate the presence of dementia.

Early detection and specificity analysis of human cytolytic T lymphocyte (CTL) colonies generated in soft agarose culture: a potential assay for definition of CTL defined (CD) determinants

In this communication we describe and early, large-scale screening assay for the detection of colonies with varied cytolytic specificity. The colonies are generated in soft agarose culture from day 3 mixed lymphocyte culture (MLC) alloactivated cells. A cell mediated lympholysis (CML) assay utilizing as few as 500 target cells has made it possible to prescreen for cytolytic T lymphocyte (CTL) colonies and to test for antigen specificities as early as 11 and 14 days, respectively, after MLC priming. Large numbers of colonies, from 80 to over 150, have been prescreened against a specific sensitizing target cell, and as many as 30 CTL colonies have been simultaneously tested against a panel of multiple targets carrying defined HLA-A, -B, -C, -DR antigens to evaluate antigen specificity. All CTL colonies are lytic against the specific sensitizing target cell and do not lyse the target autologous to the responder. Some are found to be operationally specific in that they lyse only those target cells which share HLA serologically defined (SD) antigens with the sensitizing cells, and other show cytolytic patterns which are not correlated with known HLA-SD antigens. These observations support, at a much finer level of analysis, the possible distinction between SD and CTL defined (CD) determinants.

Helper cells in murine thymus for the generation of primary cytolytic T lymphocyte (CTL) responses in vitro

Thymocytes used as responding cells in a mixed leukocyte culture with gamma-irradiated splenic stimulating cells generated highly significant proliferative and cytolytic responses when responding and stimulating cells differed by the entire H-2 complex or at H-2K plus H-21 regions. On the other hand, when the difference was only an H-2K region, very little, if any, proliferative response was detectable and no cytolytic response was found. Because it has been claimed by others that thymocytes do not include cells needed to provide the help required for the generation of a cytolytic response and yet we have found a highly significant response in thymocytes, we have analyzed, in 2 systems, the possible role of back-response by stimulating spleen cells in the generation of cytolytic activity by responding thymocytes. In the first system, spleen cells were depleted of T lymphocytes by treatment with anti-Thy-1.2 antiserum plus complement. In the second system, F1 hybrid mouse spleen cells were used to stimulate parental responding thymocytes. In both cases, no back-response as measured by cell proliferation in mixed leukocyte culture was detected, while both types of spleen cells still stimulate significant cell proliferation and cytolytic activity from responding thymocytes, as well as from responding spleen cells. Furthermore, it was found that in the presence of stimulating spleen cells (either T lymphocyte-depleted or not) that differ from the responding thymocytes at the entire H-2 complex, thymocytes were capable of generating a significant and specific cytolytic response to H-2K region different stimulating spleen cells (either T lymphocyte-depleted or not). These results are compatible with the suggestion that there are sufficient numbers of helper cells in the unfractionated thymocyte population for the generation of primary cytolytic T lymphocyte responses in vitro.

Helper cells in murine thymus for the generation of primary cytolytic T lymphocyte (CTL) responses in vitro

Thymocytes used as responding cells in a mixed leukocyte culture with gamma-irradiated splenic stimulating cells generated highly significant proliferative and cytolytic responses when responding and stimulating cells differed by the entire H-2 complex or at H-2K plus H-21 regions. On the other hand, when the difference was only an H-2K region, very little, if any, proliferative response was detectable and no cytolytic response was found. Because it has been claimed by others that thymocytes do not include cells needed to provide the help required for the generation of a cytolytic response and yet we have found a highly significant response in thymocytes, we have analyzed, in 2 systems, the possible role of back-response by stimulating spleen cells in the generation of cytolytic activity by responding thymocytes. In the first system, spleen cells were depleted of T lymphocytes by treatment with anti-Thy-1.2 antiserum plus complement. In the second system, F1 hybrid mouse spleen cells were used to stimulate parental responding thymocytes. In both cases, no back-response as measured by cell proliferation in mixed leukocyte culture was detected, while both types of spleen cells still stimulate significant cell proliferation and cytolytic activity from responding thymocytes, as well as from responding spleen cells. Furthermore, it was found that in the presence of stimulating spleen cells (either T lymphocyte-depleted or not) that differ from the responding thymocytes at the entire H-2 complex, thymocytes were capable of generating a significant and specific cytolytic response to H-2K region different stimulating spleen cells (either T lymphocyte-depleted or not). These results are compatible with the suggestion that there are sufficient numbers of helper cells in the unfractionated thymocyte population for the generation of primary cytolytic T lymphocyte responses in vitro.

Differential allo-response of murine thymocytes to H- 2 K region different recombinants and to H-2Kb mutants

Thymocytes used as responding cells in a mixed leukocyte culture with x-irradiated splenic stimulating cells generate highly significant proliferative and cytotoxic responses when responding and stimulating cells differ by the entire H-2 complex. On the other hand, when the genetic difference between responding and stimulating cells is only a K region, very little, if any, proliferative response is detectable and no cytotoxic response is found. In contrast, when responding and stimulating cell donors differ by a spontaneous mutation in the K region of the H-2 complex, as found in B6.C-H-2ba, B6-H-2bd and B6.C-H-2bf, highly significant proliferative and cytotoxic responses can be obtained. These results, thus, argue that the H-2 mutants cannot, with regard to their relationship to the parental strain, be readily equated with a K region difference as defined in the recombinant inbred strains.

Differential allo-response of murine thymocytes to H- 2 K region different recombinants and to H-2Kb mutants

Thymocytes used as responding cells in a mixed leukocyte culture with x-irradiated splenic stimulating cells generate highly significant proliferative and cytotoxic responses when responding and stimulating cells differ by the entire H-2 complex. On the other hand, when the genetic difference between responding and stimulating cells is only a K region, very little, if any, proliferative response is detectable and no cytotoxic response is found. In contrast, when responding and stimulating cell donors differ by a spontaneous mutation in the K region of the H-2 complex, as found in B6.C-H-2ba, B6-H-2bd and B6.C-H-2bf, highly significant proliferative and cytotoxic responses can be obtained. These results, thus, argue that the H-2 mutants cannot, with regard to their relationship to the parental strain, be readily equated with a K region difference as defined in the recombinant inbred strains.

Cell-mediated immunity: differential maturation of mixed leukocyte reaction and cell-mediated lympholysis

While spleen cells from neonatal B10 (H-2b) are reactive (proliferate) in one-way mixed leukocyte culture, cell-mediated lympholysis reactivity does not arise until 7 days of age. When B10 cells are sensitized to B10.D2 (H-2d), cross-killing of third-party B10.BR (H-2k) target is always lower than the specific killing of B10.D2 targets and is not demonstrable until 27 days after birth.

Stress: a factor to be considered in heterotrophic microorganism enumeration from aquatic environments

Heterotrophic microorganisms in water samples are susceptible to the transient stress of warmed agar used in the standard methods pour plate procedure, causing significantly decreased recoveries in comparison with a spread plate technique. Microbial starvation can increase susceptibility to a transient warming stress. The standard plate count procedure, as presently described, should not be considered for quantitation of microorganisms from aquatic environments.