Teratocarcinoma transplantation rejection loci: AnH-2-linked tumor rejection locus

Embryoid bodies (ascites tumor) from a 129/Sv transplantable teratocarcinoma produce tumors (100%) in syngenic 129/Sv mice but fail to form tumors (3–6%) in BALB/c mice, C3H/He mice and C57BL/6 mice, in spite of the fact that the malignant stem cells of this tumor do not express detectable H-2 antigens. The available evidence indicates that this allogeneic tumor restriction has an immunological basis; 100% of the F₁ hybrid mice between 129/Sv and the three other inbred mouse strains accept the 129/Sv teratocarcinoma. The backcross and F₂ mice segregate the BALB/c, C3H/He and C57BL/6 tumor transplantation rejection loci in a manner that indicates that each of these inbred strains of mice contain one to two major transplantation rejection loci. A linkage analysis in the BALB/c and C3H/He backcross and F₂ generations indicates that these mice have a teratocarcinoma transplantation rejection locus on chromosome 17, about eight to nine recombination units from theH- 2 complex. An F₁ complementation analysis between allogeneic mice that each reject teratocarcinomas tumors (BALB/c × C57BL/6 and C3H/He × C57BL/6), indicates that the C57BL/6 mice have the 129/Sv tumor-accepting (sensitive) allele at theH-2-linked locus but reject teratocarcinomas because of antigenic differences at a second locus.While these major teratocarcinoma transplantation rejection loci determine the acceptance or rejection of a tumor by a mouse injected with high doses of tumor tissue (750 g of tumor protein), evidence is presented for a number of minor genetic factors that can (1) affect the efficiency of tumor rejection and (2) cause complete tumor rejection at lower tumor doses (7.5–75 g of tumor protein).     

Comparative study of cholinergic cells in retinas of various mouse strains

We examined cholinergic cells in the retinas of BALB/C albino, C57BL/6J black, and 129/SvJ light chinchilla mice by using immunocytochemistry with specific antisera against choline acetyltransferase (ChAT). Two types of ChAT-immunoreactive amacrine cell bodies were found in the inner nuclear layer (INL) and ganglion cell layer in the retinas of all three mouse strains. They were distributed with mirror-image symmetry and their processes ramified in strata 2 and 4 of the inner plexiform layer. A distinct type of ChAT-immunoreactive cell was found only in C57BL/6J mouse retina. The somata of this third type of ChAT-immunoreactive cell were located in the outermost part of the INL, with their processes extending toward the outer plexiform layer. Double-labeling experiments demonstrated that these were not horizontal cells and that they were GABA-immunoreactive. The results suggested that these cells were probably misplaced cholinergic amacrine cells showing GABA immunoreactivity. This feature of the C57BL/6J mouse retina should be taken into account in studies of mutant mice having a mixed genetic background with a C57BL/6J contribution.Tae-Hoon Kang, Young-Han Ryu and In-Beom Kim contributed equally to this study.This work was supported by Neurobiology Support Grant (M1-0108-00-0059) of the Ministry of Science and Technology, Korea     

A comparative phenotypic and genomic analysis of C57BL/6J and C57BL/6N mouse strains

Background

The mouse inbred line C57BL/6J is widely used in mouse genetics and its genome has been incorporated into many genetic reference populations. More recently large initiatives such as the International Knockout Mouse Consortium (IKMC) are using the C57BL/6N mouse strain to generate null alleles for all mouse genes. Hence both strains are now widely used in mouse genetics studies. Here we perform a comprehensive genomic and phenotypic analysis of the two strains to identify differences that may influence their underlying genetic mechanisms.

Results

We undertake genome sequence comparisons of C57BL/6J and C57BL/6N to identify SNPs, indels and structural variants, with a focus on identifying all coding variants. We annotate 34 SNPs and 2 indels that distinguish C57BL/6J and C57BL/6N coding sequences, as well as 15 structural variants that overlap a gene. In parallel we assess the comparative phenotypes of the two inbred lines utilizing the EMPReSSslim phenotyping pipeline, a broad based assessment encompassing diverse biological systems. We perform additional secondary phenotyping assessments to explore other phenotype domains and to elaborate phenotype differences identified in the primary assessment. We uncover significant phenotypic differences between the two lines, replicated across multiple centers, in a number of physiological, biochemical and behavioral systems.

Conclusions

Comparison of C57BL/6J and C57BL/6N demonstrates a range of phenotypic differences that have the potential to impact upon penetrance and expressivity of mutational effects in these strains. Moreover, the sequence variants we identify provide a set of candidate genes for the phenotypic differences observed between the two strains.     

Comparative immunomodulatory properties of adipose‐derived mesenchymal stem cells conditioned media from BALB/c,C57BL/6, and DBA mouse strains

Adipose tissue‐derived mesenchymal stem cells (AD‐MSCs) have been shown to be capable of differentiating into multiple cell type and exert immunomodulatory effects. Since the selection of ideal stem cell is apparently crucial for the outcome of experimental stem cell therapies, therefore, in this study we compared AD‐MSCs conditioned media (CM) from BALB/c, C57BL/6, and DBA mouse strains. No significant difference was found in the morphology, cell surface markers, in vitro differentiation and proliferation potentials of AD‐MSCs isolated from C57BL/6, BALB/c, and DBA mice. The immunological assays showed some variation among the strains in the cytokines, nitric oxide (NO), and indoleamine 2,3‐dioxygenase (IDO) production and immunomodulatory effects on splenocytes functions. Our results indicated a suppression of splenocytes proliferation in the presence of AD‐MSC CM from the three inbred mouse strains. However, BALB/c CM exerted a higher suppression of splenocytes proliferation. AD‐MSCs isolated from C57BL/6 and BALB/c mice produced higher levels of TGF‐β than those from DBA mice. Furthermore, IL‐17 and IDO production was higher in AD‐MSCs isolated from BALB/c mice. Our results indicated an increased production of TGF‐β, IL‐4, IL‐10, NO, and IDO by splenocytes in response to CM from BALB/c AD‐MSCs. In conclusion, our results showed that the immunomodulatory properties of mouse AD‐MSCs is strain‐dependent and this variation should be considered during selection of appropriate stem cell source for in vivo experiments and stem cell therapy strategies. J. Cell. Biochem. 114: 955–965, 2013. © 2012 Wiley Periodicals, Inc.     

Different Influences of Genomic Imprinting on the Development of Parthenogenetic Cell Clones in C57BL/6 and CBA Mice

Clonal analysis of parthenogenetic chimeric mouse embryos C57BL/6(PG) BALB/c has shown that parthenogenetic cell clones C57BL/6 are present in the brain, liver, and kidneys of 14- and 18-day-old embryos. The content of the parthenogenetic component (PG) in these organs on day 18 was lower than on day 14, and, in some 18-day-old embryos, parthenogenetic cell clones were absent from the liver and/or kidneys. These data suggest that, during the embryogenesis of parthenogenetic chimeras, parthenogenetic cell clones of mostly endodermal and mesodermal origins were actively eliminated. Therefore, in such parthenogenetic adult chimeras, parthenogenetic clones of mostly ectodermal origins were preserved. In parthenogenetic chimeras CBA(PG) BALB/c, parthenogenetic cell clones were actively eliminated at early embryonic stages, and, as a result, they were absent at the post-implantation stages. Hence, during development of parthenogenetic cell clones, the effects of genomic imprinting are expressed unequally in C57BL/6 and CBA mice.     

Extracellular matrix distribution and islet morphology in the early postnatal pancreas: anomalies in the non-obese diabetic mouse

Previously, we reported elevated numbers of macrophages in the pancreas of NOD mice, a spontaneous animal model for T1D, during the early postnatal period. Extracellular matrix plays an important role in the tissue trafficking and retention of macrophages as well as in postnatal pancreas development. Therefore, we have examined the expression and distribution of laminin and fibronectin, two major extracellular matrix proteins and their corresponding integrin receptors, in the pre-weaning pancreases of NOD mice and control mouse strains. In addition, we have characterized the pancreas morphology during this period, since the morphology of the pre-weaning pancreas before the onset of lymphocytic peri-insulitis, when the pancreas is still subject to developmental changes, has been poorly documented. We show that laminin labeling is mainly associated with exocrine tissue, whereas fibronectin labeling was mostly localized at the islet-ductal pole, islet periphery and in intralobular septa. Moreover, the protein expression level of fibronectin was increased in NOD pancreases at the early stage of postnatal development, as compared to pancreases of C57BL/6 and BALB/c mouse strains. Interestingly, pancreatic macrophages were essentially found at sites of intense fibronectin labeling. The increased fibronectin content in NOD neonatal pancreas coincided with altered islet morphology, histologically reflected by enlarged and irregular shaped islets and increased percentages of total endocrine area as compared to that of control strains. In conclusion, increased levels of the extracellular matrix protein fibronectin were found in the early postnatal NOD pancreas, and this is associated with an enhanced accumulation of macrophages and altered islet morphology.This work was supported by the Centre Nationale de la Recherche Scientifique, Université Paris V and grants from the 5th PCRD MONODIAB.     

Regulatory T cells enhance susceptibility to experimental trypanosoma congolense infection independent of mouse genetic background

Background

BALB/c mice are highly susceptible while C57BL/6 are relatively resistant to experimental Trypanosoma congolense infection. Although regulatory T cells (Tregs) have been shown to regulate the pathogenesis of experimental T. congolense infection, their exact role remains controversial. We wished to determine whether Tregs contribute to distinct phenotypic outcomes in BALB/c and C57BL/6 mice and if so how they operate with respect to control of parasitemia and production of disease-exacerbating proinflammatory cytokines.

Methodology/Findings

BALB/c and C57BL/6 mice were infected intraperitoneally (i.p) with 10³ T. congolense clone TC13 and both the kinetics of Tregs expansion and intracellular cytokine profiles in the spleens and livers were monitored directly ex vivo by flow cytometry. In some experiments, mice were injected with anti-CD25 mAb prior or post T. congolense infection or adoptively (by intravenous route) given highly enriched naïve CD25⁺ T lymphocytes prior to T. congolense infection and the inflammatory cytokine/chemokine levels and survival were monitored. In contrast to a transient and non significant increase in the percentages and absolute numbers of CD4⁺CD25⁺Foxp3⁺ T cells (Tregs) in C57BL/6 mouse spleens and livers, a significant increase in the percentage and absolute numbers of Tregs was observed in spleens of infected BALB/c mice. Ablation or increasing the number of CD25⁺ cells in the relatively resistant C57BL/6 mice by anti-CD25 mAb treatment or by adoptive transfer of CD25⁺ T cells, respectively, ameliorates or exacerbates parasitemia and production of proinflammatory cytokines.

Conclusion

Collectively, our results show that regulatory T cells contribute to susceptibility in experimental murine trypanosomiasis in both the highly susceptible BALB/c and relatively resistant C57BL/6 mice.     

Characterization of single nucleotide polymorphisms for a forward genetics approach using genetic crosses in C57BL/6 and BALB/c substrains of mice

Forward genetics is a powerful approach based on chromosomal mapping of phenotypes and has successfully led to the discovery of many mouse mutations in genes responsible for various phenotypes. Although crossing between genetically remote strains can produce F₂ and backcross mice for chromosomal mapping, the phenotypes are often affected by background effects from the partner strains in genetic crosses. Genetic crosses between substrains might be useful in genetic mapping to avoid genetic background effects. In this study, we investigated single nucleotide polymorphisms (SNPs) available for genetic mapping using substrains of C57BL/6 and BALB/c mice. In C57BL/6 mice, 114 SNP markers were developed and assigned to locations on all chromosomes for full utilization for genetic mapping using genetic crosses between the C57BL/6J and C57BL/6N substrains. Moreover, genetic differences were identified in the 114 SNP markers among the seven C57BL/6 substrains from five production breeders. In addition, 106 SNPs were detected on all chromosomes of BALB/cAJcl and BALB/cByJJcl substrains. These SNPs could be used for genotyping in BALB/cJ, BALB/cAJcl, BALB/cAnNCrlCrlj, and BALB/cCrSlc mice, and they are particularly useful for genetic mapping using crosses between BALB/cByJJcl and other BALB/c substrains. The SNPs characterized in this study can be utilized for genetic mapping to identify the causative mutations of the phenotypes induced by N-ethyl-N-nitrosourea mutagenesis and the SNPs responsible for phenotypic differences between the substrains of C57BL/6 and BALB/c mice.     

Genetic control of the content and avidity of antigen-binding B-lymphocytes in the mouse spleen]

The content (per 10 nucleated cells) and avidity curves of IgM positive B-lymphocytes forming rosettes with trinitrophenyl-sheep erythrocytes (TNP-RFC) were compared in two mouse lines (BALB/c C57BL/6), F1 hybrids (BALB /c X C57BL/6) and backcross hybrids (F1 X BALB/c, F1 X C57BL/6). Trinitrophenyl-bovine serum albumin (TNP24BSA) and dinitrophenyl-bonvine serum albumin (DNP23BSA) and sulfanil-BSA (Sulf17-BSA) in different dilutions were used as inhibitors. BALB/c spleen contained by 60% more TNP-RFC than C576/6 spleen. F1 hybrids (F1 X BALB/c) contained on the average by 35% more TNP-RFC than (F1 X C57BL/6). Inhibition curves (avidity curves) were essentially different in the two mouse lines and F1 hybrids. A conclusion was drawn that the TNP-REC content and avidity were under a strong genetic control. Together with the assumption of random expression of V-genes (idiotype genes?) in the lymphocytes the above data suggest that the simplest mechanism of the genetic control could be a definitive ratio between the corresponding groups of V-genes.     

Hair barbering in mice: implications for neurobehavioural research

Barbering (fur/whisker trimming, the Dalila effect) is a behaviour-associated hair and whisker loss frequently seen in laboratory rodents, including mice. Here we analyse barbering behaviour in 129S1, NMRI, C57BL/6 and BALB/c mouse strains and some of their F1 hybrids. Our study shows that barbering in mice, depending on their genotype, is a complex behaviour with several distinct contexts or domains. We observed social (dominant) barbering in NMRI and C57BL/6 mice, sexual over-grooming in 129S1 and C57BL/6 mice, maternal barbering in lactating 129S1 and C57BL/6 mice, and stress-evoked barbering in F1 (NMRIx129S1) hybrids. In contrast, aggressive BALB/c mice and their F1 progeny do not use barbering in their behaviour. We suggest that barbering may be an important complex multi-domain behaviour sensitive to various manipulations, and represent a useful index in neurobehavioural research.     

Quantitative measurement of mouse IgG subclasses with the use of heteroantisera: the importance of allotype considerations.

Double antibody radioimmunoassays have been used to determine the quantities of IgG1, IgG2a and IgG2b in samples of normal serum IgG from BALB/cJ, AKR/J and C57BL/6J inbred mice. The assays employed subclass-specific goat antisera which had been prepared with BALB/c myeloma proteins as immunogens and as immunoabsorbents. 125I-labeled BALB/c myeloma proteins were used as probes. Results indicate that partial resolution of mouse IgG subclasses was achieved by ion exchange chromatography on DEAE-Sephadex. Nearly all of the protein in BALB/cJ and AKR/J IgG fractions could be accounted for as IgG1, IgG2a and IgG2b, and IgG2a was the predominant species observed. However, considerably less protein in C57BL/6J IgG fractions of purity similar to the BALB/cJ fractions could be accounted for as these three subclasses, and virtually no IgG2a was detected. Furthermore, an IgG2a myeloma protein bearing the C57BL/6 allotype failed to inhibit the IgG2a-specific assay significantly. Thus the IgG2a-specific antibody in the goat heteroantiserum employed appeared to consist nearly exclusively of antibody to BALB/c Ig-1a allotypic determinants. These findings point to the importance of allotype considerations in the use of heteroantisera to quantitate IgG subclasses.     

Polymorphism of class A scavenger receptors in C57BL/6 mice

Scavenger receptors class A (SR-A) have been hypothesized to regulate the development of atherosclerotic lesions through recognition of modified low density lipoprotein (LDL) and macrophage adhesion to substrata. Supporting data have been collected from studies using the monoclonal antibody 2F8, an antibody developed from the BALB/c strain-derived macrophage cell line, RAW.264. Although 2F8 immunostained both cultured peritoneal macrophages (MPM) and thymic macrophages from Swiss, BALB/c, and DBA/2 mice, no immunostaining was detected in cells and tissues from C57BL/6 mice, one of the most commonly used atherosclerosis-susceptible mouse strains. Similarly, 2F8 detected SR-A protein in MPM by Western blotting in all strains except C57BL/6. However, a guinea pig antiserum developed to a fusion protein of the extracellular SR-A domain detected appropriately sized bands in all strains. Incubation with 2F8 antagonized acetylated low-density lipoprotein (AcLDL)-induced cholesterol esterification in MPM from BALB/c, Swiss, and DBA/2 strains but had no effect on MPM from C57BL/6 mice. Sequencing of SR-A cDNA from C57BL/6 mice demonstrated complete identity with published sequence in the collagen-like domain. However, four single-residue substitutions were noted in the alpha-helical coiled-coil domain. Site-directed mutagenesis demonstrated that a single substitution (L168S) in this domain accounted for the loss of 2F8 immunoreactivity. Differing reactivities toward a commonly used monoclonal antibody were used to identify polymorphism of SR-A in C57BL/6 mice.     

Cytokines regulate the pattern of rejection and susceptibility to cyclosporine therapy in different mouse recipient strains after cardiac allografting

We determined the role of cytokines in regulating the pattern of rejection and recipient susceptibility to cyclosporine (CsA) in a mouse cardiac allograft model. Hearts from C3H mice transplanted into untreated BALB/c (Th2-dominant) and C57BL/6 (Th1-dominant) mice showed different patterns of rejection. C3H allografts in BALB/c mice showed typical acute vascular rejection (AVR) with strong intragraft deposition and high serum levels of anti-donor IgG with predominant IgG1, while C3H allografts in C57BL/6 mice showed typical acute cellular rejection (ACR) with massive intragraft infiltration of CD4(+) and CD8(+) lymphocytes and low serum levels of anti-donor IgG with predominant IgG2a. Elevated intragraft mRNA expression of IL-2, IFN-gamma, and IL-12 mRNA was present in C57BL/6 recipients, whereas allografts in BALB/c mice displayed increased IL-4 and IL-10 mRNA levels. CsA therapy completely inhibited ACR and induced indefinite allograft survival in C57BL/6 recipients, while the same therapy failed to prevent AVR, and only marginally prolonged graft survival in BALB/c recipients. In contrast, rapamycin blocked AVR, achieving indefinite survival in BALB/c recipients, but was less effective at preventing ACR in C57BL/6 recipients. The disruption of the IL-12 or IFN-gamma genes in C57BL/6 mice shifted ACR to AVR, and resulted in concomitant recipient resistance to CsA therapy. Conversely, disruption of IL-4 gene in BALB/c mice markedly attenuated AVR and significantly prolonged allograft survival. These data suggest that the distinct cytokine profiles expressed by different mouse strains play an essential role in regulating the pattern of rejection and outcome of CsA/rapamycin therapy.     

The immune response of inbred mouse strains to DNP-BGG

The immune response of six inbred mouse strains (SJL, A, C57BL/6, CBA, BALB/c, and DBA/1) to DNP₅₆BGG was tested under three separate immunization schedules: 1 Μg DNP-BGG in 1 mg Al(OH)₃ adjuvant, 50 Μg DNP-BGG in 1 mg A1(OH)₃ adjuvant, and 1 Μg DNP-BGG in complete Freund's adjuvant. Individual serum samples were titered using a modified Farr assay. It was found that the first schedule allowed classification of the mice into responder (SJL, A) and nonresponder (C57BL/6, CBA, BALB/ c, DBA/1) strains. The second schedule produced quantitative as well as qualitative differences among the strains and allowed classification of the mice into higher-responder (SJL, A), intermediate-responder (C57BL/6, CBA, BALB/c), and low-responder (DBA/1) categories. When complete Freund's adjuvant was used in the third schedule, the differences among strains became insignificant. The sera from each strain were pooled and assayed for relative antibody affinity and IgM content. Both of these parameters were dependent largely on the dose of antigen and type of adjuvant used, rather than on the particular mouse strain being studied. The mechanism of adjuvant action, and possible cell interactions in the genetic control of the immune response, are discussed.     

BCG-mediated protection against Mycobacterium ulcerans infection in the mouse

Background

Vaccination with Mycobacterium bovis bacille Calmette-Guérin (BCG) is widely used to reduce the risk of childhood tuberculosis and has been reported to have efficacy against two other mycobacterial diseases, leprosy and Buruli ulcer caused by M. ulcerans (Mu). Studies in experimental models have also shown some efficacy against infection caused by Mu. In mice, most studies use the C57BL/6 strain that is known to develop good cell-mediated protective immunity. We hypothesized that there may be differences in vaccination efficacy between C57BL/6 and the less resistant BALB/c strain.

Methods

We evaluated BCG vaccine efficacy against challenge with ∼3×10⁵ M. ulcerans in the right hind footpad using three strains: initially, the Australian type strain, designated Mu1617, then, a Malaysian strain, Mu1615, and a recent Ghanaian isolate, Mu1059. The latter two strains both produce mycolactone while the Australian strain has lost that capacity. CFU of both BCG and Mu and splenocyte cytokine production were determined at intervals after infection. Time to footpad swelling was assessed weekly.

Principal Findings

BCG injection induced visible scars in 95.5% of BALB/c mice but only 43.4% of C57BL/6 mice. BCG persisted at higher levels in spleens of BALB/c than C57BL/6 mice. Vaccination delayed swelling and reduced Mu CFU in BALB/c mice, regardless of challenge strain. However, vaccination was only protective against Mu1615 and Mu1617 in C57BL/6 mice. Possible correlates of the better protection of BALB/c mice included 1) the near universal development of BCG scars in these mice compared to less frequent and smaller scars observed in C57BL/6 mice and 2) the induction of sustained cytokine, e.g., IL17, production as detected in the spleens of BALB/c mice whereas cytokine production was significantly reduced, e.g., IL17, or transient, e.g., Ifnγ, in the spleens of C57BL/6 mice.

Conclusions

The efficacy of BCG against M. ulcerans, in particular, and possibly mycobacteria in general, may vary due to differences in both host and pathogen.     

The MHC locus controls size variations in the CD4 compartment of the mouse thymus

The genetic factors that determine the size of lymphocyte populations are largely unknown. We studied the genetic control of variations in the size of the CD4 thymic compartment in unmanipulated mouse strains. A time-course experiment showed that the C57BL/6 mouse strain has a consistently reduced proportion of thymic CD4 cells compared to the BALB/c strain. This difference denotes a decrease in the efficiency of the transition from CD4(+)CD8(+) to CD4(+) thymocytes in the C57BL/6 mouse. Genome-wide genetic mapping identified a major quantitative trait locus in the MHC region that controlled the variations in the proportion of CD4 thymocytes in an F2 intercrossed progeny from C57BL/6 and BALB/c mice (LOD score=21.7). The linkage was maximal at the MHC class II molecule Ea locus, which explained 59% of the observed phenotypic variance. As the C57BL/6 mouse does not express Ea, we hypothesize that the decreased size of the CD4 compartment in the C57BL/6 thymus is due to a reduction in the number of functional MHC class II genes. This study suggests that, at the level of the thymus, the MHC molecules in addition to conferring functional restriction and self-tolerance on the T-cell repertoire, also play a role in determining the homeostasis of the thymic compartments.     

Effect of fenazepam on the ACTH content of the blood plasma in inbred mice under stress exposure

The influence of phenazepam on plasma ACTH level before and after exposure to stress in the "open field" test was investigated in C57BL/6, BALB/c and F1(C57BL/6 X BALB/c) mice. The differences in the dose-dependent drug effect on the hormone level between strains were studied. A correlation between ACTH level and a characteristic animal behaviour has been established for different strains.     

The Contribution of Natural Killer Complex Loci to the Development of Experimental Cerebral Malaria

Background

The Natural Killer Complex (NKC) is a genetic region of highly linked genes encoding several receptors involved in the control of NK cell function. The NKC is highly polymorphic and allelic variability of various NKC loci has been demonstrated in inbred mice, providing evidence for NKC haplotypes. Using BALB.B6-Cmv1^r congenic mice, in which NKC genes from C57BL/6 mice were introduced into the BALB/c background, we have previously shown that the NKC is a genetic determinant of malarial pathogenesis. C57BL/6 alleles are associated with increased disease-susceptibility as BALB.B6-Cmv1^r congenic mice had increased cerebral pathology and death rates during P. berghei ANKA infection than cerebral malaria-resistant BALB/c controls.

Methods

To investigate which regions of the NKC are involved in susceptibility to experimental cerebral malaria (ECM), intra-NKC congenic mice generated by backcrossing recombinant F2 progeny from a (BALB/c x BALB.B6-Cmv1^r) F1 intercross to BALB/c mice were infected with P. berghei ANKA.

Results

Our results revealed that C57BL/6 alleles at two locations in the NKC contribute to the development of ECM. The increased severity to severe disease in intra-NKC congenic mice was not associated with higher parasite burdens but correlated with a significantly enhanced systemic IFN-γ response to infection and an increased recruitment of CD8⁺ T cells to the brain of infected animals.

Conclusions

Polymorphisms within the NKC modulate malarial pathogenesis and acquired immune responses to infection.     

Allelic forms of the immunoglobulin heavy chain variable region

The complete variable region sequence of the heavy chain from a phosphorylcholine-binding myeloma protein of C57/BL allotype has been determined. When this sequence was compared with the germ line-coded heavy chain variable region sequence of BALB/c phosphorylcholine-binding proteins, five differences were observed. Four of the substitutions were located in the framework portion of the variable region and the fifth in the "J" or joining segment. Two of the framework substitutions were found at positions 14 and 16. Previous studies have shown that heavy chains from all anti-phosphorylcholine antibodies induced in C57/BL mice have the same amino acids at positions 14 and 16 as the C57/BL myeloma protein described in this communication. It has therefore been concluded that these residues are encoded in the C57/BL germ line in contrast to two alternatives in the BALB/c genome. This finding, in addition to the 96% homology found between the C57/BL and BALB/c sequences, suggests that these structures represent allelic forms of an entire variable region.