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M Simonsen

Publications and source records attributed to M Simonsen.

At least 37 records · Page 2Linked to original sources
PubMed1985

Analysis of chickens for recombination within the MHC (B-complex).

In an attempt to further map the chicken MHC (the B complex), a systematic search for genetic recombinants within the B complex was performed by serotyping the progeny from F2 crosses of chickens by means of specific anti-class I, anti-class II, and anti-class IV alloantisera. Two recombinant B-haplotypes (B21r and B15r) were found by analysing 2,656 F2 chickens representing 5,312 informative typings. In either case, the B-G (class IV) allele was recombined with both the B-F and B-L alleles of the opposite haplotype. MLC typings, tests for direct compatibility by GVH reactions, and absorption analyses confirmed the original serological typing of the two recombinant B haplotypes. No recombination between B-F (class I) and B-L (class II) loci was found. This very low frequency of recombination within the B complex as compared with recombination frequencies found in mammalian MHC's is discussed.

Animals↗
PubMed1985

The physiology of the major histocompatibility complex.

The term compound receptors (C.R.) is used here to describe reversible molecular complexes in the cell membrane which attain their final biologically active structure by rearrangement and assembly of several structural subunits. The C.R. to be discussed involve the participation of the glycoproteins belonging to the major histocompatibility complex (MHC), notably of class I molecules which are themselves reversible compounds of a heavy chain and a light chain (beta 2-m). The main thesis of this discussion is the postulate that the fundamental immunological phenomenon known as MHC restriction is due to the formation in the membrane of reversible C.R. with additional roles in the physiology of the cell. The interaction between MHC class I molecules and insulin receptor molecules will be mentioned as an illustration of the general hypothesis.

Animals↗
PubMed1982

The MHC haplotypes of the chicken.

The major histocompatibility complex (MHC) of Gallus gallus is the B complex of which three classes of cell-membrane antigens have been clearly defined by serological, histogenetic, and biochemical methods. Two of these classes are homologous to classes I and II of mammals (B-F and B-L, respectively), while the third (B-G) is a differentiation antigen of the erythroid cell-line; the mammalian homologue of this class is still undefined. The B haplotypes comprise at least one gene of each class that displays linkage disequilibrium of a remarkable strength. The present work is the first systematic comparison by serological and histogenetic methods of the allelic products (allomorphs) of 15 haplotypes, including all of the 11 that were accepted as "standard" B haplotypes at the recent international Workshop on the chicken MHC in Innsbruck, Austria. The analysis has revealed many similarities, but only four pairs of probable identities: G2 and G12, F4 and F13, L4 and L13, L12 and L19. It appears therefore that the B-G locus is comparable in its degree of polymorphism to the class I (B-F) locus. The "standard" haplotypes are almost all of White Leghorn derivation, and preliminary typings of other breeds of chickens, and of wild chickens, indicate the existence of a much wider spectrum of allomorphs.

Alleles↗
PubMed1982

The major histocompatibility complex of outbred chickens. I. Analysis of the B13 haplotype by serology and cellular reactions.

The F antigens, which are serologically defined Class I gene products of the major histocompatibility complex in chickens (the B complex), were analysed in outbred birds. Private specificities of the F13 antigen from the inbred CC strain were detected in 20 outbred chickens by a haemagglutination technique. In the GVH-inhibition-release test F13 antigens from outbred and inbred chickens were identical. The L antigens, which are the Class II antigens of the B complex, were detected with specific anti L13 alloantisera by indirect immunofluorescence. Antisera defining the L13 antigen(s) of the inbred CC line reacted with all F13 positive outbreds. As a test of one-way direct compatibility of the inbred and outbred animals typing F13, graft versus host reactions were performed, injecting blood of F13 positive outbreds into inbred B13/13 eggs. No GVH stimulation attributable to MHC determinants was found. In MLR, responder cells from outbred MHC heterozygous chickens, which typed F13/x, were stimulated by inbred F13/13 homozygous typing cells, and weak, but significant, reactions were found. Further analysis in the accompanying paper, however, revealed no difference in the lymphocyte activating determinants (Lads) of inbred and outbred birds typing F13 and L13. No individual has yet been found which carries one of these antigens in the absence of the other.

Animals↗
PubMed1982

The major histocompatibility complex of outbred chickens. II. Analysis of the typing response in mixed lymphocyte culture stimulated by homozygous typing cells.

MLR phenotypes of outbred and inbred chickens typing B13 of the major histocompatibility complex (MHC) of the chicken were compared. F1 hybrids of outbred and inbred B13 positive chickens were analysed in mixed lymphocyte culture (MLC). The intermediate strength responses of cells from B13 heterozygous outbred chickens stimulated by inbred B13 homozygous chicken cells were not due to minor variations of B encoded lymphocyte activating determinants (Lads). Nor were Lads encoded by genes unlinked to the B complex responsible for these reactions. In contrast, F1 anti-parental type reactions were observed, and these alone are probably responsible for the intermediate strength reactions so often seen in typing of heterozygous outbreds with homozygous typing cells.

Animals↗
PubMed1979

Elution of chicken Ig from fixed target cells.

A method is described for preparing fixed chicken peripheral blood cells (PBC) for absorption of allo-antibodies and their subsequent elution. Glutaraldehyde fixation was satisfactory, and with 8 M urea elution haemagglutinating activity was preserved.

Adsorption↗
PubMed1978

[Basic immunology].

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Allergy and Immunology↗