Reciprocal Mixing Research Articles

The autologous mixed lymphocyte reaction in strains of mice with autoimmune disease.

We have studied the autologous mixed lymphocyte reaction (AMLR) in 3 strains of mice with autoimmune disease. T cell proliferation to autologous non-T cells occurs in young mice of these 3 strains (as it does in normal mice) but is absent or greatly reduced in older mice of strains with autoimmune disease. Reciprocal mixing experiments revealed that the defect in the AMLR of the older mice resides in the responder T cell population. Further analysis of the cells participating in the AMLR of young mice of the B/W F1 strain revealed that: 1) a Thy 1- and Ly1-positive responder cell was necessary at the start of the culture to initiate the AMLR; 2) the cells present after 5 days of culture contained very few, if any, Ly123 cells in the B/W F1 strain compared with the normal C57BL/6 strain; and 3) the stimulating cell appear to be a macrophage, and an Ia-bearing cell must be present for the reaction to occur.

Studies of immune functions of patients with systemic lupus erythematosus

In normal individuals T cells are stimulated to proliferate by autologous non-T cells; this is called the autologous mixed lymphocyte reaction (MLR). Previous studies demonstrated that such an autologous MLR was markedly impaired in patients with active systemic lupus erythematosus (SLE). To determine whether the defect resided in the responding cell or the stimulating cell, mixing experiments were performed using cells from identical twins. We identified two sets of identical twins discordant for SLE activity and correspondingly discordant in their degree of responsiveness in the autologous MLR. Reciprocal mixing experiments were performed in which T cells from one twin of each pair were mixed with non-T cells from the other twin of that pair. These studies indicated that patients with active SLE have a defect in the ability of non-T cells to stimulate as well as a defect in the ability of both Tgamma and Tnongamma cells to respond in the autologous MLR. Patients with inactive SLE have a defect only in responsiveness of Tgamma cells.

Genetic characterization of Mu-like bacteriophage D108.

Infection of Escherichia coli by bacteriophage D108 was shown to result in the generation of apparently random chromosomal mutations. Approximately 1% of the cells lysogenized by D108, as with Mu, acquired new auxotrophic mutations. D108-induced mutations were nonreverting and were most probably the result of insertion of the D108 genome into regions of genetic function. D108 and Mu shared many similar properties but were heteroimmune and had different host ranges. Lytic infections of Mu lysogens with D108 and D108 lysogens with Mu resulted in 100-fold increases in release of phage with prophage markers over those due to spontaneous induction. Phenotypic mixing was common, with most phage carrying the prophage immunity being packaged in particles with the host range of the superinfecting phage. A fraction of the superinfecting phage genomes were, however, packaged in particles with the prophage-specified host range. Although 10% of the prophage progeny were D108-Mu genetic hybrids, superinfecting phage-induced release of the prophage with reciprocal phenotypic mixing occurred in recA hosts, in which the frequency of D108-Mu genetic hybrids was reduced 100-fold.

Protein Synthesis in Cotyledons of Pisum sativum L

The changes in protein content of pea cotyledons have been followed during the period from 9 to 33 days after flowering. Initially protein content increased gradually with a rapid period of deposition occurring between days 21 and 27 after flowering. After the 28th day the rate of accumulation of protein declined as the seed dehydrated and matured. At maturity the pea cotyledon contained approximately 25% protein which was divided into albumins and globulins in the ratio of 1:1.4.Analytical data and the incorporation of exogenously supplied (14)C-leucine indicated that albumins were synthesized early in cotyledon development whereas globulin synthesis predominated with increasing maturity.Ribosomal preparations extracted from seeds during the period of rapid protein synthesis contained a high percentage of polysomes. Preparations from older cotyledons with a declining capacity for protein synthesis had few polysomes and an abundance of monosomes. The amino acid-incorporating capacity of ribosomal preparations from cotyledons of varying age was related to the polysomic content. The phenylalanine-incorporating capacity of ribosomal preparations from mature pea seed could be stimulated by the addition of polyuridylic acid. The distribution of polysomes and the in vitro incorporation data suggested that protein synthesis could be partially restricted by the availability of messenger RNA at maturity.However, reciprocal mixing experiments of supernatant and ribosomal fractions from cotyledons of different developmental age indicated that the supernatant fractions have varying capacities to stimulate in vitro amino acid incorporation. Thus the possibility of the regulation of protein synthesis at the translational level was not precluded.

Thermal conductivity of binary, ternary and quaternary mixtures of rare gases

The thermal conductivity data of the Ne-Ar, Ne-Kr, Ar-Xe and Kr-Xe systems are reported as a function of composition and at temperatures 40°, 65° and 90°c. Similar results are also presented for the ternary systems Kr-Ar-Ne, Xe-Kr-Ar and a quaternary system Xe-Kr-Ar-Ne. A conductivity cell of the thick hot-wire type is used. The thermal conductivity values for the binary mixtures are compared with those obtained from rigorous theory and such procedures as approximate, semi-theoretical, empirical, linear mixing, reciprocal mixing, combination of linear and reciprocal mixing and quadratic equations. A similar study is also made for ternary and quaternary mixtures and some interesting conclusions are drawn concerning the relative appropriateness of different methods for computing thermal conductivity of multi-component gas mixtures.