Alena Lengerová

A model for genetic analysis of programmed gene expression as reflected in the development of membrane antigens.

Abstract The red blood cell antigen determined in mice by the H-2b allele was detectable by hemagglutination at birth, H-2b-early (bE), in strain C57BL 10 , whereas that determined by H-2a not until 3 days later, H-2a-late (aL), in strain A. Each F1 individual was both aL and bE. Timing genes segregated in the F2 and BC1 generations to give H-2a-early (aE) and H-2b-late (bL) in combinations with aL and bE in apparent Mendelian ratios. In some strain combinations in which H-2 alleles and strain background had been interchanged, timing type was transferred along with H-2, whereas in others it was the background which seemed to be more important for the timing type. Moreover, no recombinant types were found in the F2 and BC1 generations of these lines. Lines originating from the (B10 × A)F2 generation were selected for reversed parental-strain-type phenotypes under a full-sib mating regime. True breeding aE or bL lines were not realized until the ninth to eleventh inbreeding generation. We propose a remote-cis-effect model consisting of one temporal gene tightly linked with H-2 and at least two others with special cis and recognition properties linked with each other but not with H-2.

H-y antigen: genetic control of the expression as detected by host-versus-graft popliteal lymph node enlargement assay maps between the t and h-2 complexes.

We are using the terms ‘low’ and ‘high’ expression when the H‐Y antigen on thymocytes of mouse parental strains is, respectively, weakly and strongly immunogenic for F1 hybrids in a host‐versus‐graft popliteal lymph node enlargement assay. Using this assay we attempted to locate the genetic factor(s) responsible for the control of H‐Y expression within chromosome 17 since our previous study indicated linkage with the H‐2 complex. We produced to this aim recombinants from (B10.T x C3H/Di)F1 hybrids where crossing over took place between H‐2 and T complexes. In this way we were able to locate a gene denoted Hye (for H‐Y expression) whose ‘high’ and ‘low’ alleles originated, respectively, from the B10 and C3H/Di strains. In the recombinants, the expression did not follow the H‐2 haplotype, but obviously depended on the position of crossing over between H‐2 and T. This pointed to the Hye gene mapping proximally from the H‐2 complex.

The Expression Of Normal Histocompatibility Antigens In Tumor Cells

Publisher Summary This chapter highlights the quantitative and qualitative characteristics of the expression in tumor cells of normal cellular antigens and the regulation of expression of cellular antigens by the impact of malignant transformation. It also covers the studies on the expression in tumor cells of normal stage- specific or tissue-specific antigens and the possible role of the specificity of membrane architecture in normal and pathological morphogenesis. For many years, the antigenic analysis of tumor cells was mainly motivated by the search for antigens specifically associated with the malignant character and clearly distinguishing the tumor cells from their normal precursors. The chapter lists out various reasons for the alterations in the cell membrane structure that sometimes accompany malignant transformation in the expression of normal antigens, particularly histocompatibilty (H) antigens. It also covers the level of regulation as revealed by the analysis of somatic cell hybrids. There might be a relationship between the malignant transformation and expression of normal histocompatibility antigens.

Intercellular adhesiveness of h-2 identical and h-2 disparate cells.

Using a 2 times 2 design, the collection rates of cells from radioactively labelled single‐cell suspensions on cell‐coated collecting surfaces were tested for a possible H‐2 effect on intercellular adhesiveness. By a statistical procedure, the undesirable variability in the suspension and/or in the collecting surface could be eliminated, and the H‐2 specific net effect estimated. In this way it was possible to detect (even on the background of a large non‐specific variability) significant reductions of the allogeneic collection rates (i.e. between cells which differed only in their H‐2 haplotypes) as compared to the syngeneic standards. It is concluded that cells of a given H‐2 haplotype have preferential adhesiveness to syngeneic cells.

RADIATION CHIMERAS AND GENETICS OF SOMATIC CELLS.

The Lunar Receiving Laboratory will be the permanent depository of a portion of the collection of lunar samples; it will safeguard the collection, providing continuing security and ensuring scientific integrity. In carrying out the time-dependent experiments and continuing functions of the laboratory, NASA will rely on visiting expert scientists supplementing a relatively small resident staff; outside scientists will be relied upon for most investigations and detailed analyses of samples. It is believed that the designed procedures and facilities provided will ensure the maximum scientific return from the Apollo Program in the way of information from lunar samples.

STRUCTURAL RELATIONSHIPS BETWEEN INDIVIDUAL H-2 SPECIFICITIES ON THE CELL SURFACE

Stepwise incubation with specific H‐2 antibody and rabbit‐anti‐mouse Ig was used to modulate the expression of selected H‐2 specificities on the surface of lymph node cells or EL 4 leukaemia cells. Modulation was reflected in a loss of sensitivity to complement‐dependent lysis and a polar pattern of immunofluorescence (‘capping’). Specificity H‐2.5 on H‐2a cells was co‐modulated with H‐2.11 and so was H‐2.11 with H‐2.5 on H‐2k cells. However, when H‐2.11 on H‐2k cells was modulated, the cells did not loose cytotoxic sensitivity for H‐2.5. This asymmetry in co‐modulation of H‐2.5 and H‐2.11 may be accommodated by the duplication model of the H‐2 complex which postulates a double determination of H‐2.5 in the H‐2k (unlike H‐2a) chromosome, with one determinant being in the K region (where also the H‐2.11 determinant is located) and the other in H‐2D. The modulation results with H‐2.5 and H‐2.11 are compatible with the view that various H‐2K specificities may represent distinct antigenic sites on the same glycoprotein molecule whereas H‐2D specificities are on separate molecule(s). The independent modulation of H‐2D.4 and H‐2K.11 specificities further indicates that molecules of the two classes are also secondarily not linked in the membrane structure. Modulation‐induced cytotoxicity resistance was further shown to persist even when the specific H‐2 antibody is newly added; this suggests that it is a change in the distribution of the H‐2 antigen to be held responsible (rather than the loss of the sensitizing antibody).

Cytochalasin B-induced changes in concanavalin A-activated lymphocytes

SummaryCytochalasin B (CB) administered simultaneously with a mitogenic dose of concanavalin A (Con A) interferes with the activation process. This interference involves structural alterations of cellular membrane which do not include a reduced Con A-binding capacity. This conclusion is supported by the observation of deformities in both nuclear and cytoplasmic membranes in Con A-activated lymphocytes subsequently treated with CB. The high incidence of membrane blebs and pseudomyelin bodies in the cytoplasm points to a general effect of CB on the structural organization of membrane which may secondarily interfere with some specific event such as generation or transfer of signals for activation or cytokinesis.

ANALYSIS OF GENETIC DIFFERENCES IN EARLY VERSUS LATE AGGLUTINABILITY WITH H‐2 ANTIBODIES OF NEONATAL MOUSE ERYTHROCYTES

Neonatal red blood cells (RBC) of some mouse strains are agglutinable by H‐2 antibodies immediately after birth (early strains, E) while others only on day 3 (late strains, L). Previous genetic analysis led to the conclusion that there are at least three ‘temporal’ genes controlling the timing of agglutinability. In the present study, we attempted to throw some light on the way in which these genes function by defining the phenotypic difference(s) between H‐2 agglutinable (E) and non‐agglutinable (L) neonatal RBC. We found that the E vs L difference was not manifested in two other assays, for in agglutination with lectins (Con A and PHA) both cell types behaved as E while in formation of alloclusters with H‐2 specific lymphocytes both behaved as L. Unlike H‐2aE, H‐2aL (native) neonatal RBC had virtually no detectable antibody‐absorbing capacity, however, following digestion with trypsin or neuraminidase (NANAse) they acquired both antibody‐absorbing capacity and agglutinability. In contrast to it, adult RBC lost agglutinability following GA‐fixation, but this could not be counteracted by trypsinization. Neonatal H‐2aL RBC could be made agglutinable by the action of dimethylsulphoxide (DMSO) or by an admixture of adult H‐2a RBC. The results are thus compatible with a hypothesis that the H‐2 receptors on neonatally non‐agglutinable (L) RBC are not absent, but in a state interfering with agglutinability; a poor accessibility to antibody may be due to a rigid integration of H‐2 sites with the cell membrane which prevents their antibody‐mediated juxtaposition to similarly rigid receptors on other cells. The possible nature of the allelic difference between E and L H‐2 receptors is discussed.