LCIS and tamoxifen use: A single institution review

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Background: Results of the NSABP-P1 trial were published in 1998 showing a 50% reduction in breast cancer in the high- risk population with the use of tamoxifen. The use of tamoxifen is individualized, and depends on both patient and physician factors. We looked at the recommendations for and the use of tamoxifen in women with LCIS. Methods: A retrospective chart review at a single institution was performed from March 27, 1980 through September 19, 2005 for patients diagnosed with LCIS. Pathology and operative reports, as well as patient notes were reviewed for discussions about tamoxifen. Data was collected on whether a discussion took place, whether tamoxifen was or was not advised, whether the patient declined to take tamoxifen, whether they took it in the past or were currently on tamoxifen. We also examined the rate of DCIS and invasive cancer in this population. Results: There were 321 patients diagnosed with LCIS. Of those patients 193 were diagnosed after the publication of the P1 trial. Of these 193 patients we identified 104(54%) patients whose charts contained notes indicating a discussion about tamoxifen. The results of the discussion about tamoxifen are as follows: 21(20%) patients were currently taking tamoxifen, 16(15%) had taken it in the past, 37(36%) patients declined to take tamoxifen, and 17(16%) had not made a decision about taking tamoxifen. There were 13(13%) patients for whom tamoxifen was advised against. In the entire cohort of 321 patients, 15% went on to develop DCIS or invasive cancer in the first 12 years of follow up. We did not look at cancer rate Vs tamoxifen use due to the small numbers with available information. Conclusions: While the P1 trial recommends tamoxifen for breast cancer prevention in high-risk patients, in our experience, almost half of the patients did not have a documented discussion about the medication, and the majority of those who did decided not to take tamoxifen. This will likely have a large impact on the rate of DCIS and invasive breast cancer in this group.

No significant financial relationships to disclose.

Why are cesarean delivery rates so high in diabetic pregnancies?

AIMS

The purpose of this study was to examine factors relevant to mode of delivery in term pregnancies complicated by gestational and pre-gestational diabetes.

METHODS

A retrospective chart review of term (> or = 37 weeks) singleton pregnancies complicated by Class A2 through Class R pregnancies which delivered from 1991-1997 was performed. Exclusion criteria were prior cesarean delivery, non-vertex presentation, fetal structural defects, or any contraindications to vaginal delivery. Maternal and fetal factors relevant to mode of delivery were examined and compared. Stepwise logistic regression analysis was performed to examine factors predictive of delivery mode.

RESULTS

A total of 148 patients met study criteria. Induction rates were 60.9% for gestational and 79.8% for pre-gestational diabetics. The overall cesarean delivery rate by Diabetes Class for A2, B, C, D-F pregnancies was 20.3%, 40%, 37%, and 57.1% respectively. In Class A2 pregnancies no factor was associated with cesarean delivery and only nulliparity (p = 0.03) was associated in Class B-F pregnancies.

CONCLUSIONS

These results suggest that physician factors may play an important role in the risk for cesarean delivery in our diabetic population.

Vaginal birth after cesarean in the diabetic gravida

OBJECTIVE

To compare the delivery outcomes in term diabetic patients without a prior cesarean delivery to those attempting vaginal birth after cesarean (VBAC).

STUDY DESIGN

A retrospective chart review study was performed of singleton pregnancies complicated by class A-2-R diabetes who delivered at > or = 37 weeks from 1991 to 1997. Exclusion criteria were prior classical or low vertical cesarean, more than one prior cesarean delivery, fetal structural defects or any contraindications to labor. Outcome measures were compared for patients without prior cesarean (group 1) to those with a VBAC attempt (group 2).

RESULTS

One hundred fifty-nine patients, 127 patients without a prior cesarean delivery and 32 patients with a VBAC attempt, met all the study criteria. The cesarean delivery rate was 26.3% (34/127) in group 1 and 56.3% (18/32) in group 2 (VBAC success rate, 43.7%). There were no cases of uterine rupture. There were no differences in the frequency of endometritis rates or neonatal intensive care unit admission, whether vaginal or cesarean delivery occurred.

CONCLUSION

VBAC success rates appeared to be lower for diabetic gravidas as compared to those for nondiabetic women reported in the literature. Although maternal and neonatal complication rates were low, further studies are necessary to determine the safety of VBAC in this population.

Declining bone mass in men with chronic pulmonary disease: contribution of glucocorticoid treatment, body mass index, and gonadal function

BACKGROUND

Men with chronic lung disease (CLD) are at risk for osteoporosis, but the relative contributions of their chronic pulmonary disease, glucocorticoid therapy, and other factors toward loss of bone has not been established. Understanding the relative importance of these factors would assist in selecting patients for bone densitometry screening and in policy decisions regarding Medicare reimbursement.

OBJECTIVE

To identify patients with CLD who are most likely to benefit from bone densitometry screening based on clinical and biochemical measures.

DESIGN

Cross-sectional medical survey.

PATIENTS

Patients with CLD who were treated with either oral, inhaled, or no glucocorticoid therapy. A control group without lung disease was recruited from the same clinic population.

MEASUREMENTS

Dual-energy X-ray absorptiometry was obtained for each group, and the association between bone mass and clinical variables, glucocorticoid use, gonadal hormones, and biochemical markers of bone metabolism was determined.

RESULTS

Osteoporosis (a T score < -2.5 at the hip or spine) was five times as likely in patients with CLD as in control subjects. Although the prevalence of osteoporosis was higher (ninefold) after chronic glucocorticoid therapy, patients with CLD who had never been treated with glucocorticoids had a substantial (fourfold) risk of osteoporosis. Chronic inhaled glucocorticoid therapy offered no protection from bone loss compared to treatment with oral glucocorticoids. Of the clinical and biochemical measures that were obtained, bone mass was weakly correlated with body mass index (BMI), serum estradiol-17beta, and N-telopeptide, but not with testosterone, alkaline phosphatase, bone-specific alkaline phosphatase, or osteocalcin.

CONCLUSION

Patients with CLD should be considered for bone densitometry screening regardless of glucocorticoid use. Those patients with a low BMI and/or decreased serum estradiol-17beta comprise a subgroup with increased risk for osteoporosis.

The role of molecular discreteness in normal and cancerous growth

The physicochemical events that underlie biological processes are inevitably either/or events. Either a growth factor molecule binds to a cell, or it doesn't. Either a site on a cyclin molecule is phosphorylated, or it isn't. Either a regulatory molecule binds to a DNA sequence, or it doesn't. These molecular either/or events lead to cellular either/or events. Either a cell divides, or it doesn't. Either a cell dies, or it doesn't. Either a cell turns on a particular gene, or it doesn't. Either a tumor cell stays where it is, or it forms a distant metastasis. By considering biological processes as the macroscopic aggregate results of these many individual microscopic either/or events, we can gain considerable insight into both normal and cancerous growth. In fact, as will be outlined here, such discrete modeling may allow us to see how the normal cellular populations of the body can grow to predictable sizes, at predictable times, and to predictable shapes. Such modeling can also allow us to gain insight into how normal cellular populations may become cancerous cellular populations. Indeed, such an approach allows us do a sufficiently good job of imitating the growth and spread of tumors as to be able to make estimates the most effective ways to both detect and treat cancer.

Analysis of the structure and expression of the augmenter of liver regeneration (ALR) gene

BACKGROUND

The gene encoding the hepatotrophic factor Augmenter of Liver Regeneration (ALR) has recently been cloned in the rat. The availability of the mouse form of ALR would allow the analysis of the role of this factor in the physiology of liver and other organs, while the identification of the human homolog would allow the transfer of the great wealth of information that has been generated in animal models to clinically oriented pilot trials, and eventually the therapeutic application of this information.

MATERIALS AND METHODS

Standard molecular biology approaches have been used to determine the genomic structure of the ALR gene in the mouse, and to characterize the ALR transcript and its protein product. The human ALR cDNA was also isolated and the amino acid sequence of the human gene product deduced. The mapping of mouse and human ALR genes on mouse and human chromosomes was then completed.

RESULTS

The protein coding portion of the mouse ALR gene is comprised of three exons, the first containing the 5' untranslated sequence and the initial 18 bases after the ATG translation initiation codon, the second exon encompasses 198 bases, and the third exon contains the remaining portion of the protein coding sequence. Rat, mouse, and human ALR genes (and protein products) were found to be highly conserved and preferentially expressed in the testis and in the liver. The ALR gene maps to the mouse chromosome 17, in a region syntenic with human chromosome 16, where the T/t region has also been mapped.

CONCLUSIONS

ALR appears to be a protein with important physiologic properties, not exclusively limited to liver regeneration, with roles that are involved in the synthesis or stability of the nuclear and mitochondrial transcripts that are present in actively regenerating cells, particularly the germ cells of the testes.

Laryngeal preservation by induction chemotherapy plus radiotherapy in locally advanced head and neck cancer: the M. D. Anderson Cancer Center experience

Standard treatment of locally advanced laryngeal, hypopharyngeal, and some oropharyngeal cancers includes total laryngectomy. In an attempt to preserve the larynx through induction chemotherapy, we conducted two consecutive phase II studies. From March 1986 to February 1991, 64 patients with advanced untreated but resectable head and neck cancer who would require total laryngectomy were enrolled on one of two cisplatin-based induction regimens: cisplatin-bleomycin-5-fluorouracil (PBF) in 31 patients and cisplatin-5-fluorouracil (PF) in 33; all received definitive radiotherapy. Surgery was reserved for patients who achieved less than a partial response to chemotherapy and patients with residual or recurrent disease after sequential chemotherapy plus radiotherapy. Overall complete plus partial response rates to both cisplatin-based regimens were comparable. The combined PF and PBF overall response rates were 75% for laryngeal cancer, 78% for hypopharyngeal cancer, and 75% for oropharyngeal cancer. Complete response rates after radiotherapy were 88%, 83%, and 50%, respectively. Neutropenia (< 1,000 cells/mm3) was the most common hematologic toxic effect: it occurred in 44% of patients who received PF and 16% of those who received PBF. Grade > or = 3 mucositis occurred in 50% of patients who received PF and 4% who received PBF. The data suggest that laryngeal preservation was feasible in all three primary-site subgroups. With follow-up of 15+ to 54+ months, 44% of patients with laryngeal cancer, 28% with hypopharyngeal cancer, and 22% with oropharyngeal cancer are alive with laryngeal preservation. The overall 2-year survival rates for patients with cancer of the larynx, hypopharynx, and oropharynx were 71%, 46%, and 38%, respectively.

Fetal leg and femur/foot length ratio: a marker for trisomy 21

OBJECTIVE

Our purpose was to determine whether the femur/foot length ratio is useful in the prenatal detection of trisomy 21.

STUDY DESIGN

Direct necropsy measurements were analyzed on 436 midgestational fetuses (391 normal, 45 with trisomy 21). Necropsy leg/foot length ratio versus gestational age was found to be significantly different between normal fetuses and those with trisomy 21. On the basis of the necropsy data, 345 midgestational pregnancies were evaluated ultrasonographically for femur/foot length ratio versus gestation age to identify fetuses at risk for trisomy 21.

RESULTS

A leg/foot length ratio versus gestation age < or = 2.3 correctly identified 84% of fetuses with trisomy 21 between 110 to 155 days gestation age at necropsy. An ultrasonographic femur/foot length ratio versus gestational age < or = 0.9 had an 18.3 odds ratio risk for trisomy 21 in our high-risk population and correctly identified 71% of fetuses with trisomy 21 (positive predictive value 0.24, negative predictive value 0.98).

CONCLUSION

The femur/foot length ratio is an additional ultrasonographic marker for identification of fetuses at increased risk for trisomy 21.

Lymphocytes with a CD4+ CD8- CD3- phenotype are effectors of experimental cutaneous graft-versus-host disease

Graft-versus-host disease (GVHD) is known to cause profound dysregulation of the immune system, although its effector mechanisms are poorly understood. We now describe an effector lymphocyte of unusual phenotype in the skin of mice with GVHD. This cell is of donor origin and expresses several T-cell surface proteins including Thy-1, CD2, and CD4 but does not express CD8, CD3, NK1.1, or macrophage antigens. Mononuclear cells of this phenotype are the predominant lymphocyte in the epidermis of mice with GVHD 3 weeks after transplant but are not detected in transplanted mice without GVHD. Isolation and transfer of these lymphocytes into secondary recipients causes epidermal damage characteristic of GVHD. These data demonstrate that CD4+ CD8- CD3- lymphocytes are an important effector population that can be amplified outside the thymus and that can mediate target organ damage of GVHD.

Evidence for an intrinsic B cell defect in lpr/lpr mice apparent in neonatal chimeras

Stem cells from a lpr/lpr mouse do not cause the lpr syndrome characteristic of unmanipulated MRL/lpr mice when injected into nonautoimmune neonatal mice. Instead, these neonatal chimeras gradually become markedly lymphopenic. As adults, only limited donor cell engraftment (approximately 5%) was evident as assessed by cell surface staining of H-2D or Thy-1 allelic markers. However, the relatively low number of lpr/lpr-derived B cells produced greater than 90% of the circulating IgG2a antibody and all detectable IgG2a anti-ssDNA autoantibody, indicating that lpr/lpr B cells express an intrinsic genetic defect resulting in hyper-IgG and autoantibody secretion.

Evidence for an intrinsic B cell defect in lpr/lpr mice apparent in neonatal chimeras

Stem cells from a lpr/lpr mouse do not cause the lpr syndrome characteristic of unmanipulated MRL/lpr mice when injected into nonautoimmune neonatal mice. Instead, these neonatal chimeras gradually become markedly lymphopenic. As adults, only limited donor cell engraftment (approximately 5%) was evident as assessed by cell surface staining of H-2D or Thy-1 allelic markers. However, the relatively low number of lpr/lpr-derived B cells produced greater than 90% of the circulating IgG2a antibody and all detectable IgG2a anti-ssDNA autoantibody, indicating that lpr/lpr B cells express an intrinsic genetic defect resulting in hyper-IgG and autoantibody secretion.

Evidence that anti-asialo GM1 in vivo improves engraftment of T cell-depleted bone marrow in hybrid recipients

Engraftment of T cell-depleted bone marrow was studied in a P----F1 murine bone marrow transplant model which features long-term stability of mixed chimerism of donor (B6) and host (B6AF1) cells after BMT. We report that a polyclonal antibody to asialo GM1 (anti-ASGM1) given in vivo after transplant was able to increase long-term donor bone marrow engraftment. In vivo anti-ASGM1 eliminated NK activity but did not affect the generation of cytotoxic T cells nor did it stimulate hematopoiesis in vitro. Anti-Thy 1.2, a pan-T cell monoclonal antibody, had no effect on donor engraftment. We conclude that ASGM1+ cells with NK activity inhibit the long-term engraftment of bone marrow stem cells in this model and that antibodies to NK cells can be used in vivo as an effective component of the transplant conditioning regimen.

Engraftment following T cell-depleted bone marrow transplantation. III. Differential effects of increased total-body irradiation on semiallogeneic and allogeneic recipients

Three different doses of total-body irradiation (TBI) (1100, 1300, 1500 cGy) have been analyzed as conditioning regimens for semiallogeneic B6AF1 (H-2b X H-2a) and allogeneic A/J (H-2a) recipients of T cell-depleted C57BL6 (H-2b) bone marrow transplants. Recipient survival and engraftment of both donor erythrocytes and lymphocytes were examined in each group. The large majority of allogeneic mice prepared with 1100 cGy rejected their grafts, which resulted in poor survival (less than 30%); improved survival (up to 80%) and complete donor engraftment were noted as the TBI dose was increased. By contrast, survival in semiallogeneic B6AF1 recipients was independent of TBI dose and was greater than 80% in all groups. Outright failure of marrow grafts (less than 10% donor hematopoiesis) did not occur in these recipients, but mixed chimerism (simultaneous occurrence of both donor and host cells) was frequently observed at lower TBI doses. Complete (greater than 90%) donor engraftment was noted for erythrocytes but not for lymphocytes. Possible mechanisms accounting for these differences between semiallogeneic and allogeneic recipients of marrow transplants are discussed.

Engraftment following T-cell-depleted bone marrow transplantation. II. Stability of mixed chimerism in semiallogeneic recipients after total-body irradiation

Chronic, stable mixed chimerism of both lymphocytes and erythrocytes was observed in semiallogeneic murine recipients of T-cell-depleted bone marrow transplants that had been conditioned with supralethal total-body irradiation (1100 cGy). Mixed chimerism was extensive, with a wide range of donor engraftment persisting for at least one year after transplant. In both erythrocyte and lymphocyte lineages, decreasing donor engraftment correlated with decreasing marrow dose; however, complete red cell engraftment was more easily achieved than complete lymphocyte engraftment. There were no late graft failures, even among animals exhibiting a substantial host component of hematopoiesis. The extent of mixed hematopoietic chimerism therefore appears to be much greater than had been expected in recipients of T-cell-depleted bone marrow transplants.

Selective elimination of non-lpr lymphoid cells in mice undergoing lpr-mediated graft-vs-host disease

The transfer of lpr BM stem cells into lethally irradiated non-lpr recipients (including the congenic MRL/+ differing only at the lpr locus) causes GVHD characterized by a wasting syndrome. In this study we investigated the interaction between the autoimmune (lpr) and normal (A-Thy) B, T, and RBC cell lineages in two types of radiation chimeras: MRL/lpr plus A-Thy----(MRL/lpr X A-Thy)F1 and MRL/+ plus A-Thy----(MRL/lpr X A-Thy)F1. Analysis of B cell repopulation by competitive RIA of serum Igh-1 allotype showed that both the MRL and the A-Thy donor cells initially engrafted. However, by 2 to 4 mo post-transplantation the normal A-Thy allotype was barely detectable (reduced greater than 2 orders of magnitude), whereas the autoimmune MRL/lpr allotype persisted at normal levels. Similarly, investigation of the donor origin of peripheral blood T cells by two-color flow cytometry showed that by 8 mo post-transplantation normal A-Thy T cells had been eliminated and only MRL/lpr T cells were present in the circulation. In contrast, erythrocytes from both the MRL/lpr and A-Thy donor strains successfully engrafted the F1 recipients and persisted until the termination of the study. Control chimeras transplanted with a mixture of MRL/+ plus A-Thy BM were stably engrafted with both donor strains in both the erythroid and lymphoid populations. Additional experiments in which either B6/lpr or MRL/lpr (and B6/+ or MRL/+ control) BM cells were transferred into (MRL/lpr X B6/+)F1 and (MRL/lpr X B6/lpr)F1 recipients demonstrated that the development of GVHD was not simply due to increased alloreactivity by the lpr donor cells. In these chimeras only the recipients heterozygous (but not homozygous) for the lpr gene developed lpr-GVHD, although both types of recipients had identical genotypes except at the lpr locus.

Selective elimination of non-lpr lymphoid cells in mice undergoing lpr-mediated graft-vs-host disease

The transfer of lpr BM stem cells into lethally irradiated non-lpr recipients (including the congenic MRL/+ differing only at the lpr locus) causes GVHD characterized by a wasting syndrome. In this study we investigated the interaction between the autoimmune (lpr) and normal (A-Thy) B, T, and RBC cell lineages in two types of radiation chimeras: MRL/lpr plus A-Thy----(MRL/lpr X A-Thy)F1 and MRL/+ plus A-Thy----(MRL/lpr X A-Thy)F1. Analysis of B cell repopulation by competitive RIA of serum Igh-1 allotype showed that both the MRL and the A-Thy donor cells initially engrafted. However, by 2 to 4 mo post-transplantation the normal A-Thy allotype was barely detectable (reduced greater than 2 orders of magnitude), whereas the autoimmune MRL/lpr allotype persisted at normal levels. Similarly, investigation of the donor origin of peripheral blood T cells by two-color flow cytometry showed that by 8 mo post-transplantation normal A-Thy T cells had been eliminated and only MRL/lpr T cells were present in the circulation. In contrast, erythrocytes from both the MRL/lpr and A-Thy donor strains successfully engrafted the F1 recipients and persisted until the termination of the study. Control chimeras transplanted with a mixture of MRL/+ plus A-Thy BM were stably engrafted with both donor strains in both the erythroid and lymphoid populations. Additional experiments in which either B6/lpr or MRL/lpr (and B6/+ or MRL/+ control) BM cells were transferred into (MRL/lpr X B6/+)F1 and (MRL/lpr X B6/lpr)F1 recipients demonstrated that the development of GVHD was not simply due to increased alloreactivity by the lpr donor cells. In these chimeras only the recipients heterozygous (but not homozygous) for the lpr gene developed lpr-GVHD, although both types of recipients had identical genotypes except at the lpr locus.

The lpr gene is associated with resistance to engraftment by lymphoid but not erythroid stem cells from normal mice

This study demonstrates cell lineage-specific resistance to engraftment involving lymphocytes but not erythrocytes by the spontaneously autoimmune MRL/lpr mouse strain. In these experiments, MRL/lpr mice were lethally irradiated (1000 R) and reconstituted with normal A-Thy bone marrow stem cells. Periodic analysis from 6 wk to 6 mo posttransplantation demonstrated that the T and B cells of these chimeras were derived from the MRL/lpr host. However, in the same A-Thy----MRL/lpr chimeras, erythrocyte repopulation was completely of A-Thy donor origin. In contrast, control MRL/+ (congenic mice that differ from MRL/lpr at the lpr locus and do not develop accelerated autoimmune disease) recipients were successfully repopulated in both the lymphoid and erythroid compartments by the A-Thy donor cells.

The lpr gene is associated with resistance to engraftment by lymphoid but not erythroid stem cells from normal mice

This study demonstrates cell lineage-specific resistance to engraftment involving lymphocytes but not erythrocytes by the spontaneously autoimmune MRL/lpr mouse strain. In these experiments, MRL/lpr mice were lethally irradiated (1000 R) and reconstituted with normal A-Thy bone marrow stem cells. Periodic analysis from 6 wk to 6 mo posttransplantation demonstrated that the T and B cells of these chimeras were derived from the MRL/lpr host. However, in the same A-Thy----MRL/lpr chimeras, erythrocyte repopulation was completely of A-Thy donor origin. In contrast, control MRL/+ (congenic mice that differ from MRL/lpr at the lpr locus and do not develop accelerated autoimmune disease) recipients were successfully repopulated in both the lymphoid and erythroid compartments by the A-Thy donor cells.

Biochemical genetics of TL antigens

TL antigens are class I glycoproteins which are expressed on thymocytes and which are coded by the Tla region of the major histocompatibility complex of the mouse. Biochemical analysis of TL molecules from different strains of mice revealed structural variation determined by the Tla region which is detectable by peptide mapping, isoelectric focusing, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, two-dimensional gels, and by differential reactivity of allelic forms of TL molecules with a panel of anti-TL reagents. The quantity of TL expressed on thymocytes is also influenced by the Tla region; three quantitative phenotypes were identified: high (Tlaa, Tlad, Tlae), intermediate (Tlac, Tlaf), and low (Tlab). (Relative amounts: 1000: 100: 1.) Some thymic leukemias arising in (Tlab, Tlac) mice with genetically determined reduced levels of thymic TL were found to express TL molecules which were structurally indistinguishable from TL isolated from thymocytes but were present in larger amounts. This suggests that TL structural genes are intrinsically capable of full expression in all mice but that the Tla region of mice expressing an intermediate or low quantity of TL is marked by some feature which causes the thymocyte to express less than the full amount of TL possible.

Unusual association of beta 2-microglobulin with certain class I heavy chains of the murine major histocompatibility complex

Class I products of the major histocompatibility complex (MHC) comprise a heavy chain of about 45 kDa noncovalently linked to a 12-kDa beta 2-microglobulin (beta 2m) light chain encoded on a different chromosome. We find that class I products of some mouse strains include an additional 62-kDa molecule which on the following evidence consists of a heavy chain linked covalently with beta 2m. Production of the 62-kDa protein invariably accorded with the occurrence of cysteine at position 121 of the heavy chain (Kb,Kbm1,Kbm3,Dd, and Ld). Substitution of arginine at position 121 invariably accorded with absence of the 62-kDa protein (Kbm6,Kbm7,Kbm9,Kd, and Db). On the basis of observed production versus nonproduction of the 62-kDa molecule, predictions are made regarding residue 121 in class I products for which this is not yet known; namely, Kk, Ks, and Dk, which produce the 62-kDa molecule, as compared with Kj, Qa-2, and TL, which do not. Reported differences in immunologic reactivity between Kb mutant strains with Arg-121 in place of Cys-121 imply that the occurrence of 62-kDa class I products in mice of Cys-121 genotype has functional consequences.

Allogeneic reactivity in normal mouse serum

Normal C57BL/6 (B6) mouse serum was tested in the direct cytotoxicity assay for specific reactivity against lipopolysaccharide (LPS)-stimulated mouse spleen cells. Selective reactivity was found in weanling and adult serum against lymphoblasts from mice that express an antigen encoded by the H-2Kk region of the major histocompatibility complex (MHC). Other strains, congenic with B6 at the MHC, did not exhibit the same alloreactivity. Serum from mice of a congenic strain being derived in our laboratory, which differs from B6 at two unlinked loci, Tla and nu, exhibited similar reactivity against the B6-H-2k LPS-stimulated lymphoblasts, implying that a competent T cell compartment is not necessary for generation of this reactivity. Such reactivities may result from environmental stimulation of the immune system, from internal immunoregulatory controls, or from some combination of these immune stimuli.

The alpha-globin pseudogene on mouse chromosome 17 is closely linked to H-2

DNA sequences homologous to adult alpha-globin genes are dispersed in the mouse. Two functional genes are tightly linked on chromosome 11. Pseudogenes have been assigned to chromosomes 15 and 17 by analysis of interspecies somatic cell hybrids. We have now further characterized the second of these pseudogenes, Hba-a4. The gene is highly polymorphic, with three forms occurring in a panel of 15 inbred strains and a fourth occurring in an inbred strain derived from M. m. molossinus. Analysis of Hba-a4 alleles in CXB, BXH, and AKXL recombinant inbred strains placed Hba-a4 6.60 +/- 3.14 cM centromeric to H-2. Analysis of congenic mouse strains confirmed the linkage and the gene order. Hba-a4 is the first mammalian dispersed pseudogene to be localized in a linkage map, and should provide a useful marker for the region of chromosome 17 proximal to H-2.

The biochemical genetics of TL antigens on mouse thymocytes

Molecules bearing thymus leukemia (TL) alloantigen were isolated by immunoprecipitation from detergent-solubilized thymocyte lysates. Antisera used included monoclonal antibodies (anti-TL.m1, anti-TL.m2, anti-TL.m3), monospecific anti-TL.5 alloantisera and multispecific anti-TL.1,2,3,5 antiserum. Apparently, each of these reagents immunoprecipitates the same single 45,000 molecular weight Tla gene product as shown by identity on sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), isoelectric focusing and by sequential precipitation studies. Allelic TL molecules, coded by the Tlaa and Tlad genes, were shown to be distinguishable by SDS-PAGE, and tryptic peptide mapping experiments. Both allelic TL molecules could be isolated from thymocytes of (Tlaa x Tlad)F1 mice. These results suggest that, at least for the Tlaa-Tlad allelic differences, the polymorphism and antigenicity of TL is determined by variation in amino acid composition.

cis-Interacting genes in the S region of the murine major histocompatibility complex

Insight into the control of gene expression may be gained by analysing genetic systems marked by both regulatory and structural variants. In such systems one can determine whether a regulatory element controls structural genes on both chromosomes or only on the chromosome to which it is linked. The latter may be detected in individuals heterozygous at both the regulatory and structural loci, in which case the effect of each regulatory allele is seen to be exerted only on the cis-located structural allele. In prokaryotic organisms, the identification of cis interaction of this sort has allowed elucidation of many features of genetic regulation, first for the lac operon and subsequently for a variety of other systems. In higher organisms, however, there have been few opportunities to observe cis-interacting genes. The most thoroughly characterized mammalian system in this regard is the murine beta-glucuronidase locus described by Paigen and his colleagues, in which cis interaction has been shown to occur between two closely linked genetic elements-the beta-glucuronidase structural gene itself and an androgen-activated regulatory gene which controls the quantity of beta-glucuronidase expressed. We report here that cis-interacting genetic elements are also found in the S region of the mouse major histocompatibility complex H-2.

Further biochemical data on Qa-2

The Qa-2 differentiation alloantigen is coded by a gene situated between the D and Tla loci of the murine major histocompatibility complex (H-2). Qa-2-bearing protein was isolated by immunoprecipitation and found to be composed of subunits of 40 000 and 12 000 daltons by SDS polyacrylamide gel electrophoresis (PAGE). The 12 000 dalton material was identified as beta 2-microglobulin (beta 2M) by its molecular weight (SDS PAGE), charge (isoelectric focusing), antigenicity (reactivity with xenogenic anti-beta 2M), and genetics. The 40 000 dalton mol. wt. of Qa-2 heavy chains is 5 000 daltons less than that of D and K molecules (45 000 daltons). The quantity of Qa-2 isolated by immunoprecipitation was found to vary in strain-specific fashion and as much as a 15-fold difference was observed.

H-2-controlled polymorphism of the gamma chain of Slp (sex-limited protein)

A genetic polymorphism detected by the O'Farrell two-dimensional technique (isoelectric focusing and SDS-PAGE) of the murine sex-limited protein (Slp) is described and shown to map to the H-2 complex. The Slp charge variation was found to be in the gamma chains. Inbred strains carrying the H-2w7 and H-2wr7 haplotypes, which are derived from a wild mouse, had Slp-gamma chains with pI = 6.55 (Slp-1b). All other inbred strains, bearing H-2j,H-2s,H-2p,H-2d,H-2u, as well as three additional Slp-constitutive wild females captured in Chile, had Slp-gamma chain with pI = 6.71 (Slp-1a).

A polymorphism of the gamma-chain of mouse C4 controlled by the S region of the major histocompatibility complex

Three phenotypes of the gamma-chain of mouse C4 have been detected by a modification of the two-dimensional O'Farrell technique. Strains carrying the H-2s, H-2p, H-2f and H-2ja haplotypes had chains with pI 7.4 (gamma 1). Strains with H-2k, H-2q, H-2d, H-2r, H-2b, H-2u, and H-2w7 had gamma-chains with pI 6.9 (gamma 2), and strains carrying a wild-derived haplotype had gamma chains with pI 6.5 (gamma 3). The genes controlling this polymorphism were mapped in the S region of the H-2 complex by using congenic strains.

A polymorphism of the gamma-chain of mouse C4 controlled by the S region of the major histocompatibility complex

Three phenotypes of the gamma-chain of mouse C4 have been detected by a modification of the two-dimensional O'Farrell technique. Strains carrying the H-2s, H-2p, H-2f and H-2ja haplotypes had chains with pI 7.4 (gamma 1). Strains with H-2k, H-2q, H-2d, H-2r, H-2b, H-2u, and H-2w7 had gamma-chains with pI 6.9 (gamma 2), and strains carrying a wild-derived haplotype had gamma chains with pI 6.5 (gamma 3). The genes controlling this polymorphism were mapped in the S region of the H-2 complex by using congenic strains.

Analysis of thymus-leukemia (TL) antigens with monoclonal antibodies

Lysates of radioiodinated thymocytes have been sequentially immunoprecipitated with monoclonal antibodies specific for thymus-leukemia (TL) antigens. The TL antigenic specificities defined by the monoclonal antibodies appear not to correspond precisely to specificities previously defined with conventional alloantisera. Nonetheless, each of two monoclonal antibodies specific for a single TL determinant was found to deplete lysates of B6.Tlaa thymocytes of all molecules precipitable by an alloantiserum specific for the conventionally defined determinants TL.1,2,3,5, and 6. These results suggest that on B6.Tlaa thymocytes, all the conventional TL antigenic specificities (TL. 1,2,3,5,6) as well as the specificities defined by the monoclonal anti-TL antibodies (TL.m2,m3) are carried by a single molecular species.

Analysis of thymus-leukemia (TL) antigens with monoclonal antibodies

Lysates of radioiodinated thymocytes have been sequentially immunoprecipitated with monoclonal antibodies specific for thymus-leukemia (TL) antigens. The TL antigenic specificities defined by the monoclonal antibodies appear not to correspond precisely to specificities previously defined with conventional alloantisera. Nonetheless, each of two monoclonal antibodies specific for a single TL determinant was found to deplete lysates of B6.Tlaa thymocytes of all molecules precipitable by an alloantiserum specific for the conventionally defined determinants TL.1,2,3,5, and 6. These results suggest that on B6.Tlaa thymocytes, all the conventional TL antigenic specificities (TL. 1,2,3,5,6) as well as the specificities defined by the monoclonal anti-TL antibodies (TL.m2,m3) are carried by a single molecular species.