The art of coarse Stokes: Richardson extrapolation improves the accuracy and efficiency of the method of regularized stokeslets

The method of regularized stokeslets is widely used in microscale biological fluid dynamics due to its ease of implementation, natural treatment of complex moving geometries, and removal of singular functions to integrate. The standard implementation of the method is subject to high computational cost due to the coupling of the linear system size to the numerical resolution required to resolve the rapidly varying regularized stokeslet kernel. Here, we show how Richardson extrapolation with coarse values of the regularization parameter is ideally suited to reduce the quadrature error, hence dramatically reducing the storage and solution costs without loss of accuracy. Numerical experiments on the resistance and mobility problems in Stokes flow support the analysis, confirming several orders of magnitude improvement in accuracy and/or efficiency.

Rapid sperm capture: high-throughput flagellar waveform analysis

STUDY QUESTION

Can flagellar analyses be scaled up to provide automated tracking of motile sperm, and does knowledge of the flagellar waveform provide new insight not provided by routine head tracking?

SUMMARY ANSWER

High-throughput flagellar waveform tracking and analysis enable measurement of experimentally intractable quantities such as energy dissipation, disturbance of the surrounding medium and viscous stresses, which are not possible by tracking the sperm head alone.

WHAT IS KNOWN ALREADY

The clinical gold standard for sperm motility analysis comprises a manual analysis by a trained professional, with existing automated sperm diagnostics [computer-aided sperm analysis (CASA)] relying on tracking the sperm head and extrapolating measures. It is not currently possible with either of these approaches to track the sperm flagellar waveform for large numbers of cells in order to unlock the potential wealth of information enclosed within.

STUDY DESIGN, SIZE, DURATION

The software tool in this manuscript has been developed to enable high-throughput, repeatable, accurate and verifiable analysis of the sperm flagellar beat.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Using the software tool [Flagellar Analysis and Sperm Tracking (FAST)] described in this manuscript, we have analysed 176 experimental microscopy videos and have tracked the head and flagellum of 205 progressive cells in diluted semen (DSM), 119 progressive cells in a high-viscosity medium (HVM) and 42 stuck cells in a low-viscosity medium. Unscreened donors were recruited at Birmingham Women's and Children's NHS Foundation Trust after giving informed consent.

MAIN RESULTS AND THE ROLE OF CHANCE

We describe fully automated tracking and analysis of flagellar movement for large cell numbers. The analysis is demonstrated on freely motile cells in low- and high-viscosity fluids and validated on published data of tethered cells undergoing pharmacological hyperactivation. Direct analysis of the flagellar beat reveals that the CASA measure 'beat cross frequency' does not measure beat frequency; attempting to fit a straight line between the two measures gives ${\mathrm{R}}^2$ values of 0.042 and 0.00054 for cells in DSM and HVM, respectively. A new measurement, track centroid speed, is validated as an accurate differentiator of progressive motility. Coupled with fluid mechanics codes, waveform data enable extraction of experimentally intractable quantities such as energy dissipation, disturbance of the surrounding medium and viscous stresses. We provide a powerful and accessible research tool, enabling connection of the mechanical activity of the sperm to its motility and effect on its environment.

LARGE SCALE DATA

The FAST software package and all documentation can be downloaded from www.flagellarCapture.com.

LIMITATIONS, REASONS FOR CAUTION

The FAST software package has only been tested for use with negative phase contrast microscopy. Other imaging modalities, with bright cells on a dark background, have not been tested but may work. FAST is not designed to analyse raw semen; it is specifically for precise analysis of flagellar kinematics, as that is the promising area for computer use. Flagellar capture will always require that cells are at a dilution where their paths do not frequently cross.

WIDER IMPLICATIONS OF THE FINDINGS

Combining tracked flagella with mathematical modelling has the potential to reveal new mechanistic insight. By providing the capability as a free-to-use software package, we hope that this ability to accurately quantify the flagellar waveform in large populations of motile cells will enable an abundant array of diagnostic, toxicological and therapeutic possibilities, as well as creating new opportunities for assessing and treating male subfertility.

STUDY FUNDING/COMPETING INTEREST(S)

M.T.G., G.C., J.C.K-B. and D.J.S. gratefully acknowledge funding from the Engineering and Physical Sciences Research Council, Healthcare Technologies Challenge Award (Rapid Sperm Capture EP/N021096/1). J.C.K-B. is funded by a National Institute of Health Research (NIHR) and Health Education England, Senior Clinical Lectureship Grant: The role of the human sperm in healthy live birth (NIHRDH-HCS SCL-2014-05-001). This article presents independent research funded in part by the NIHR and Health Education England. The views expressed are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health. The data for experimental set (2) were funded through a Wellcome Trust-University of Birmingham Value in People Fellowship Bridging Award (E.H.O.).The authors declare no competing interests.

Simulations of particle tracking in the oligociliated mouse node and implications for left-right symmetry-breaking mechanics

The concept of internal anatomical asymmetry is familiar-usually in humans the heart is on the left and the liver is on the right; however, how does the developing embryo know to produce this consistent laterality? Symmetry-breaking initiates with left-right asymmetric cilia-driven fluid mechanics in a small fluid-filled structure called the ventral node in mice. However, the question of what converts this flow into left-right asymmetric development remains unanswered. A leading hypothesis is that flow transports morphogen-containing vesicles within the node, the absorption of which results in asymmetrical gene expression. To investigate how vesicle transport might result in the situs patterns observe in wild-type and mutant experiments, we extend the open-source Stokes flow package, NEAREST, to consider the hydrodynamic and Brownian motion of particles in a mouse model with flow driven by one, two and 112 beating cilia. Three models for morphogen-containing particle released are simulated to assess their compatibility with observed results in oligociliated and wild-type mouse embryos: uniformly random release, localized cilium stress-induced release and localized release from motile cilia themselves. Only the uniformly random release model appears consistent with the data, with neither localized release model resulting in significant transport in the oligociliated embryo. This article is part of the Theo Murphy meeting issue 'Unity and diversity of cilia in locomotion and transport'.

Non-identifiability of parameters for a class of shear-thinning rheological models, with implications for haematological fluid dynamics

Choosing a suitable model and determining its associated parameters from fitting to experimental data is fundamental for many problems in biomechanics. Models of shear-thinning complex fluids, dating from the work of Bird, Carreau, Cross and Yasuda, have been applied in highly-cited computational studies of hemodynamics for several decades. In this manuscript we revisit these models, first to highlight a degree of uncertainty in the naming conventions in the literature, but more importantly to address the problem of inferring model parameters by fitting to rheology experiments. By refitting published data, and also by simulation, we find large, flat regions in likelihood surfaces that yield families of parameter sets which fit the data equally well. Despite having almost indistinguishable fits to experimental data these varying parameter sets can predict very different flow profiles, and as such these parameters cannot be used to draw conclusions about physical properties of the fluids, such as zero-shear viscosity or relaxation time of the fluid, or indeed flow behaviours. We verify that these features are not a consequence of the experimental data sets through simulations; by sampling points from the rheological models and adding a small amount of noise we create a synthetic data set which reveals that the problem of parameter identifiability is intrinsic to these models.

Model-based image analysis of a tethered Brownian fibre for shear stress sensing

The measurement of fluid dynamic shear stress acting on a biologically relevant surface is a challenging problem, particularly in the complex environment of, for example, the vasculature. While an experimental method for the direct detection of wall shear stress via the imaging of a synthetic biology nanorod has recently been developed, the data interpretation so far has been limited to phenomenological random walk modelling, small-angle approximation, and image analysis techniques which do not take into account the production of an image from a three-dimensional subject. In this report, we develop a mathematical and statistical framework to estimate shear stress from rapid imaging sequences based firstly on stochastic modelling of the dynamics of a tethered Brownian fibre in shear flow, and secondly on a novel model-based image analysis, which reconstructs fibre positions by solving the inverse problem of image formation. This framework is tested on experimental data, providing the first mechanistically rational analysis of the novel assay. What follows further develops the established theory for an untethered particle in a semi-dilute suspension, which is of relevance to, for example, the study of Brownian nanowires without flow, and presents new ideas in the field of multi-disciplinary image analysis.

CASA: tracking the past and plotting the future

The human semen sample carries a wealth of information of varying degrees of accessibility ranging from the traditional visual measures of count and motility to those that need a more computational approach, such as tracking the flagellar waveform. Although computer-aided sperm analysis (CASA) options are becoming more widespread, the gold standard for clinical semen analysis requires trained laboratory staff. In this review we characterise the key attitudes towards the use of CASA and set out areas in which CASA should, and should not, be used and improved. We provide an overview of the current CASA landscape, discussing clinical uses as well as potential areas for the clinical translation of existing research technologies. Finally, we discuss where we see potential for the future of CASA, and how the integration of mathematical modelling and new technologies, such as automated flagellar tracking, may open new doors in clinical semen analysis.

Destructive skeletal lesions as the primary initial manifestation of acute childhood leukemia

Bony involvement in leukemia has been long recognized in the medical literature. However, severe osseous changes, as the sole initial manifestation of childhood leukemia is a unique feature of the case reported here.

A 64,000 dalton matrix protein of human cytomegalovirus induces in vitro immune responses similar to those of whole viral antigen

Human cytomegalovirus contains approximately 30 to 35 structural polypeptides. Although antibodies to several of these proteins are made during natural infection, their relationship to T cell recognition of this virus and subsequent control of infection is poorly understood. We have purified one of these proteins (HCMVgp64) that is found in abundance in infected cell lysates in order to delineate the relationship of single viral proteins to the immune response caused by the virus. HCMVgp64 induced T cell reactivity only in individuals with serologic evidence of past infection. In addition, HCMVgp64 elicited similar in vitro immune reactions as the whole virus including T cell proliferation, interleukin 2 production, and receptor expression as well as interferon production. These studies suggest that single proteins of HCMV such as HCMVgp64 are capable of inducing T cell responses and may be important in the development of immune reactivity to HCMV.

A 64,000 dalton matrix protein of human cytomegalovirus induces in vitro immune responses similar to those of whole viral antigen

Human cytomegalovirus contains approximately 30 to 35 structural polypeptides. Although antibodies to several of these proteins are made during natural infection, their relationship to T cell recognition of this virus and subsequent control of infection is poorly understood. We have purified one of these proteins (HCMVgp64) that is found in abundance in infected cell lysates in order to delineate the relationship of single viral proteins to the immune response caused by the virus. HCMVgp64 induced T cell reactivity only in individuals with serologic evidence of past infection. In addition, HCMVgp64 elicited similar in vitro immune reactions as the whole virus including T cell proliferation, interleukin 2 production, and receptor expression as well as interferon production. These studies suggest that single proteins of HCMV such as HCMVgp64 are capable of inducing T cell responses and may be important in the development of immune reactivity to HCMV.

Extravascular hemolysis following the administration of cefamandole

Hemolytic anemia occurred in a 70-year-old female after a five-day course of intravenous cefamandole. The patient's serum contained an IgG antibody which was reactive with red blood cells which had been coated in vitro with cefamandole but not with uncoated cells. An in vitro assay of allogeneic mononuclear phagocytosis of cefamandole-coated red cells sensitized with the patient's anti-cefamandole indicated that the anti-cefamandole could induce significant phagocytosis. The anti-cefamandole was easily inhibited in vitro by cefamandole as well as by a variety of related cephalosporins indicating broad cross-reactivity, with the antigenic site primarily the 7-amino-cephalosporanic acid nucleus. Penicillins could inhibit the anti-cefamandole but only when using concentrations 3-10 X those of cephalosporins. Eleven examples of anti-penicillin tested failed to react with cefamandole-coated red cells. Screening of 344 random sera from hospitalized patients found only five (1.5%) reactive with cefamandole-coated red cells; three of these sera were also reactive with penicillin-coated red cells. The patient's hemolysis subsided following cessation of the drug. This is the first report of anti-cefamandole-induced hemolytic anemia.

In vitro determination of red cell alloantibody significance using an assay of monocyte-macrophage interaction with sensitized erythrocytes

One hundred and forty-eight red cell alloantibodies, of specificities generally considered to be of clinical significance, were studied in vitro for their ability to induce phagocytosis of sensitized red cells by allogeneic mononuclear phagocytes. Results indicate that only 53% of the alloantibodies studied mediated significant phagocytosis in vitro. The percentages for each blood group system were as follows: Kell, 73%; Jka, 32%; Jkb, 67%; D, 75%; E, 60%; Fya, 62%; Yta, 25%; Ge, 22%; and Vel, 25%. Significant phagocytosis was independent of the strength of the indirect antiglobulin test. The percentage of anti-Jka and anti-Fya mediating significant phagocytosis was increased when fresh complement was added during the sensitization procedure and/or red cells homozygous for the antigen in question were used. The in vivo clinical significance or lack of significance was documented for nine alloantibodies; five caused haemolysis and four did not. Those causing in vivo haemolysis mediated in vitro phagocytosis by monocyte-macrophages whereas the antibodies that did not result in haemolysis showed no increased in vitro phagocytosis. Autologous monocytes were more reliable than random allogeneic monocytes in that phagocytosis was increased over that obtained using allogeneic monocyte-macrophages with two of four alloantibodies having documented clinical significance. The use of target red cells homozygous for the antigen in question, the addition of fresh complement in the antibody sensitization procedure, and use of autologous and allogeneic monocyte-macrophages appear necessary for optimal results. Since 47% of those alloantibodies generally considered to be clinically significant failed to mediate phagocytosis in vitro, the monocyte-macrophage assay should not be considered a predictive assay of a given alloantibody's in vivo significance or lack of significance until more extensive correlation of these assays with in vivo red blood cell survival is obtained.

Reticuloendothelial cell function in alpha-methyldopa-induced hemolytic anemia

2 patients having alpha-methyldopa-induced hemolytic anemia were followed sequentially using an in vitro assay of autologous monocyte-macrophage activity to determine if their reticuloendothelial system (RES) function was abnormal and thus could be related to the mechanism of lysis. RES function was evaluated while the patients were actively hemolyzing and during remission, following discontinuance of the drug. The results indicated that RES activity is normal in patients having hemolytic anemia due to alpha-methyldopa administration. Also, following cessation of drug therapy, the patients' IgG-coated red cells interacted significantly for a prolonged period (4-5 months) with autologous or normal allogeneic monocyte-macrophages. This was associated with a concurrent reticulocytosis and indicates a persistent low-level hemolytic phase throughout this period, even though hemoglobin and hematocrit values remained within the normal ranges. Although levels of IgG sensitizing the patients' red cells were essentially constant during the hemolytic phase and when the patients were in complete remission, significant monocyte-macrophage activity was only evident during the hemolytic period. In an attempt to explain this phenomenon, it is postulated that hemolysis in patients receiving alpha-methyldopa is related to the interaction of drug with red cell membrane proteins which results in a variably expressed 'altered' antigen which is recognized by 'autoantibody'. The proper expression of the Fc portion of the immunoglobin molecule to result in specific recognition by receptors on monocyte-macrophages depends upon the extent of the antigen alteration by alpha-methyldopa. If the drug does not result in appropriate antigen alteration, then, although 'autoantibody' may still bind to the red blood cell, its Fc region is not readily recognized by monocyte-macrophages and little or no erythrophagocytosis occurs.

Anti-M causing delayed hemolytic transfusion reaction

A 52-year-old gravida 1, para 1 woman with M- red cells experienced a delayed hemolytic transfusion reaction and exhibited an anti-M antibody following the infusion of four units of M+ red cells. Measurements of erythrocyte survival using 51Cr-labeled donor M+ and M- red cells and in vitro studies of monocyte-macrophage phagocytosis of sensitized reagent red cells implicate anti-M in the pathogenesis of hemolysis.

Evaluation of reticuloendothelial function in autoimmune hemolytic anemia using an in vitro assay of monocyte-macrophage interaction with erythrocytes

We have used an in vitro assay of monocyte-RBC interaction to study the correlation of in vitro monocyte activity with in vivo lysis in patients with autoimmune hemolytic anemia (AIHA). All of 16 patients with a positive direct antiglobulin test (DAT) (0.5 + to 4+) and clinical evidence of hemolysis showed elevated association (ARBC) and phagocytic (PRBC) indices. Of 6 patients studied with a positive DAT (0.5+ to 4+) without clinical evidence of hemolysis, none showed elevated PRBC while 2 showed slightly elevated ARBC. Thus, when using a PRBC index, our assay distinguished between hemolysing and non-hemolysing patients independent of the degree of red cell sensitization as determined by the DAT. In addition, we have studied 6 patients with a positive DAT following alpha-methyldopa therapy. Two of these patients were hemolysing, 4 were not. Again, our assay correlated with in vivo lysis. Finally, we have studied red cells from 11 patients with DAT-negative acquired hemolytic anemia. Seven of these patients showed elevated ARBC and PRBC indices, indicating a possible immune etiology involving extravascular lysis in some DAT-negative acquired hemolytic anemias.

lack of suppressor cell activity for natural killer cells in infant, aged and a low responder strain of mice

We have examined the reported role of suppressor cells in the regulation of NK activity in mice with naturally low NK activity (infant and aged (C57 X A)F1 hybrids (CAF1) and low responder strain AKR mice). Possible suppressor activity was assayed by mixing, at a 1 : 1 ratio, spleen cells from low activity mice with spleen effector cells from normally active 8 to 10 wk old CAF1 mice. The lytic activity of the mixture was compared with the activity of effector cells diluted with medium alone or diluted 1 : 1 with "non-suppressor" population which served as a control for nonspecific decreases in lysis. The control or "filler" cells employed were suspensions of adult CAF1 thymus, thymus from adult mice exposed to 2,000 R, and adult CAF1 spleen cells cultured for 24 hours, a procedure that depleted NK activity. In no case was the activity observed in the presumed suppressor-effector mixture significantly lower than that observed in the filler-effector cell mixtures. Thus, in infant (1 to 2 wk) and aged (12 to 18 mo) CAF1 mice and in 8 to 10 wk old AKR mice, we found no evidence for specific cell-mediated suppression of natural cytotoxicity.

Augmentation of natural killer cell activity in spleens of infant, aged, and low responder strain mice by Corynebacterium parvum

Murine natural killer (NK) cell activity is both age- and strain-dependent. NK activity does not appear in murine spleen cells until three weeks after birth. Activity peaks at approximately 10 weeks, decreasing thereafter with mice over one year old showing significantly reduced levels. Mice showing low or no NK activity because of age (aged and infant mice, respectively) can be stimulated to show significant levels of NK lysis by i.p. injection of formalin killed Corynebacterium parvum (CP). In addition, CP treatment is also capable of increasing NK activity in mice from the normally low responding AKR strain. The NK activity induced or stimulated by CP appears to be like normal NK reactivity in that it is not decreased by removal of T-cells or adherent cells. Thus, in addition to increasing NK activity in normally responsive mice, CP is capable of augmenting NK activity in mice which normally show low or no levels of NK lysis.

Development of natural killer cell activity and genetic resistance to bone marrow transplantation with age: effect of neonatal thymectomy

The effect of neonatal thymectomy on the development of splenic and bone marrow natural cell-mediated cytotoxicity and on genetic resistance to bone marrow transplantation was examined in mice. Natural cytotoxicity was measured by a 51Cr release assay; the ability to engraft foreign bone marrow was assayed by the spleen colony method. The natural cytolytic response of spleen cells increased progressively from youth to early adulthood, whereas that of the bone marrow declined during the same age period. Neonatal thymectomy significantly elevated the natural killer cell response of young mice only (4 weeks, spleen; 6 weeks, bone marrow). In other experiments, neonatally thymectomized and sham-operated mice were lethally irradiated at 4 or 6 weeks of age and injected with 2.5, 5.0 or 10 million rat marrow cells. Six days later spleen colonies were markedly reduced in both 4- and 6-week-old neonatally thymectomized mice with all rat marrow cell doses tested. Neonatal thymectomy did not alter the percentage of erythroid verus other colonies at either 4 or 6 weeks. In both thymectomized and sham-operated mice the number of colonies increased with increases in marrow cell dose. The data are suggestive of a production and dissemination to the spleen of cels involved in the natural cytotoxic response from the bone marrow.

Amelioration of graft-versus-host disease by pretreatment of allogeneic cells with Fab fragments

We have previously reported the protective effect of pretreatment of semiallogeneic marrow and spleen cells with Fab fragments of horse anti-mouse thymocyte globulin against otherwise 100% fatal acute graft-versus-host disease (GVHD). We have now examined the effect of this pretreatment in three allogeneic strain combinations of mice, namely, A leads to C57, CBA leads to CAF1, and CBA leads to BALB/c. Acute GVHD mortality at 15 days postirradiation and transplantation of untreated marrow and spleen cells was 100% in all the strain combinations. However, pretreatment of cells with Fab reduced acute GVHD mortality to 6, 13, and 33% for the CBA leads to CAF1, CBA leads to BALB/c, and A leads to C57 strain combinations, respectively. The combined mortality from both acute and secondary GVHD and all other causes at 60 and 200 days postirradiation was 6 and 11%, 20 and 39%, 50 and 66% for each of these strain combinations, respectively. These results provide additional evidence for the effectiveness of Fab in ameliorating acute GVHD and establish its applicability to allogeneic strain combinations.

Comparative effects of different strains of Corynebacterium parvum on natural cell-mediated cytotoxicity

Because there are conflicting reports regarding the effects of Corynebacterium parvum (CP) on natural killer (NK) cell activity, several different strains of CP were compared. In replicate experiments, age- and sex-matched mice received 0.25-mg i.p. injections of one of four types of CP; formalin-killed strain 6134; heat-killed strain 6134; formalin-killed strain 5888 (actually Corynebacterium granulosum); or formalin-killed CP from the Pasteur Institute. At various days thereafter, two to three mice from each group were sacrificed to determine spleen weight, cellularity, and NK cell activity versus YAC-1 lymphoma cells. The CP from the Pasteur Institute augmented NK cell activity 3 days following injections; however, the activity returned to normal by Day 7 and remained at that level. On the other hand, strain 5888 did not cause as great an increase in lytic activity as did the Pasteur Institute CP at Day 3; but by Day 10 after injection, NK cell levels were above control, and they remained elevated through Day 21. Both the heat-killed and formalin-killed preparations of strain 6134 stimulated NK cell activity initially but resulted in a loss of activity at the later times tested. Experiments done with different doses and routes of injection yielded similar results. Thus, we were able to demonstrate that different types of CP have different effects on NK cell activity in mice and that the general kinetics of these effects were independent of dose or route of administration.

The abrogation of in vivo resistance to parental bone marrow transplantation and of in vitro natural cell-mediated cytotoxicity to the YAC lymphoma by in vivo growth of a transformed thymus-derived cell culture

A thymus-derived monolayer culture, referred to as E1, from (C57Bl/6 X A)F1 hybrid mice was continuously passaged in vitro for over three years and formed rapidly growing, non-metastasizing tumors when injected s.c. into syngeneic mice. The spleens of tumor-bearing mice were greatly enlarged, but no tumor cells were detected in these spleens. The natural cell-mediated cytotoxic activity of spleen cells of tumor-bearing mice decreased with increasing tumor size. In addition, the expression of genetic resistance to transplantation of C57Bl/6 parental bone marrow cells was decreased in the spleens of irradiated tumor-bearing mice. This correlation between the expressions of natural cell-mediated cytotoxicity and of genetic resistance to bone marrow transplantation is consistent with the hypothesis that both of these responses are mediated by the same population of effector cells.

Augmentation of erythroid burst formation by the addition of thymocytes and other myelo-lymphoid cells

Bone marrow from barrier-sustained specific pathogen-free (SPF) CBA and C57BL/6 mice gave relatively low numbers of BFU-E colonies in methylcellulose culture, as compared to conventional mice. Addition of thymocytes to the marrow cultures increased the yield of BFU-E colonies more than fourfold in SPF mice but only 1.5-fold in conventional mice. Colony size was also increased. Increased yield of BFU-E colonies was also obtained by co-culture of bone marrow with lymph node cells or with bone marrow or spleen cells from 900R whole-body irradiated mice. The effect appeared to be cellular rather than humoral. It was not reproduced by conditioned medium from thymus or pokeweed mitogen stimulated spleen cells. The helper effect of thymus cells was eliminated or reduced by freezing and thawing, or by 48 hours of incubation after irradiation. Treatment of bone marrow cells in vitro with anti-theta serum and complement did not decrease the number of BFU-E colonies. The putative helper cells appear not to be T cells, were non-adherent to the plastic culture dish, and were cortisone resistant and radioresistant. The low BFU-E colony yield from SPF mouse marrow is presumed to be largely the result of deficiency of these non-T helper cells in SPF bone marrow, rather than of BFU-E progenitor cells.

Genetic resistance to bone marrow transplantation as a leukemia-lymphoma defense mechanism: correlation of "in vivo" lymphoma resistance and "in vitro" NK activity

(C57 X AKR) F1 hybrid mice, which show genetic resistance to C57 parental bone marrow cells and to AKR lymphoma but not to AKR bone marrow cells in vivo, also show high natural killer cell lysis versus lymphoma cells in vitro. (C3H X AKR) F1 hybrids which show no genetic resistance to parental bone marrow cells or to lymphoma cells in vivo have low levels of NK activity like those of the low responding AKR strain. Thus genetic resistance to bone marrow transplantation and to lymphoma in vivo, correlates with NK lytic activity versus lymphoma cells in vitro, adding to the evidence linking these phenomena.

Apparent identity of mechanisms of genetic resistance to marrow transplantation and natural killer cell activity

Because the phenomenon of in vitro lysis of lymphoma cells by spleen natural killer (NK) cells bears genetic and effector cell resemblances to genetic resistance to bone marrow transplantation, they were compared for additional known unique characteristics of the latter phenomenon. Like GR to BMT, NK cell activity first appeared abruptly at about 3 weeks of post-natal age; was radioresistant to 1 100 R whole body irradiation, but was quantitatively diminished by higher exposures or delay of test post-irradiation; was suppressed by pretreatment with either cyclophosphamide, carrageenan, silica particles, anti-bone marrow serum or anti-thymus serum. The many unique identical characteristics of these two effector mechanisms indicates that they represent two manifestations of the same basic phenomenon of natural immunity. This is in accord with other data indicating that GR to BMT is directed at Hh antigens which, like TL antigens, may in some mouse strains appear on both leukemic cells and normal hemopoietic cells.

Genetic resistance to marrow transplantation as a leukemia defense mechanism

(C57 X AKR) F1 hybrid mice show genetic resistance to C57 parental bone marrow cells, but not to AKR parental bone marrow cells. (C3H X AKR) F1 hybrids show no genetic resistance to bone marrow transplantation from either parental strain. Transplantation of AKR lymphoma cells into lethally irradiated "resistant" (C57 X AKR) F1 and "non-resistant" (C3H X AKR) F1 hybrids produce lymphomatous spleen colonies in "non-resistant" hybrids but not in "resistant" hybrids. Thus "resistant" (C57 X AKR) F1 hybrids can recognize and reject AKR lymphoma cells, but not normal AKR bone marrow cells. A normal biological role of lymphoma surveillance is postulated for genetic resistance.

"Xenogeneic resistance" to rat bone marrow transplantation. III. Maturation age, and abrogation with cyclophosphamide, Corynebacterium parvum and fractionated irradiation

Lethally irradiated C57 Bl/6 mice and (C57 X A) F1 hybrids fail to accept doses of rat bone marrow cells (5 X 10(6)) which give confluent splenic repopulation in "non-resistant" strains of mice. This phenomenon has been termed "xenogeneic resistance" (XR). XR in (C57 X A) F1 mice can be overridden by a very large inoculum of rat bone marrow (26 X 10(6) cells). XR is not manifest in mice of a resistant strain at ages of 18 days or younger, but is manifest at ages of 22 days and older. XR can be abrogated by agents as varied as: 1) cyclophosphamide, which abrogates XR in a dose dependent manner when given 1 hr prior to lethal irradiation and bone marrow transplantation 2) C. parvum, which abrogates resistance when given 7 days prior to lethal irradiation and bone marrow transplantation, and 3) Fractionated irradiation, which, while capable of abrogating XR, is much less potent than either cyclophosphamide or C. parvum.