The requirement for macrophages in the secondary immune response to antigens of small and large size in vitro

Tissue culture techniques were combined with cell separation procedures, antimacrophage serum and soluble and particulate forms of sheep red cell antigen to investigate the cellular requirements for a secondary antibody response. By using the highly efficient active adherence column separation method of Shortman which almost completely removes phagocytic cells, it was found that the secondary response to SRC was macrophage dependent. This conclusion was verified by the use of specific antimacrophage serum and by a combination of both methods. Critical tests were used to verify that these separation methods acted on phagocytic and not on other cells, for example, thymus or bone marrow derived lymphocytes. In contrast, the secondary immune response to POL and solubilized SRC antigen was not dependent on the presence of phagocytic cells, as highly purified lymphocytes responded normally to these antigens. Antimacrophage serum did not depress the immune response to these soluble antigens. These results indicate that the requirement for macrophage activity depends on the physical size of the antigen. These findings, obtained in the secondary response in vitro, were closely analogous to previous findings from this laboratory on the cellular basis of the primary response to SRC and POL. The reasons for the different cellular bases of the secondary immune response to various molecular forms of antigen are discussed. The similar cellular basis of the primary and secondary response in vitro suggests that the basic mechanisms of immunization in these responses are the same.

Bat and soil studies for sources of histoplasmosis in Florida

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The Marlowe-Crowne, repressor-sensitizer, and internal-external scales and attribution of unconscious hostile intent

Two follow-up experiments demonstrated weak and inconsistent relationships between attribution of unconscious hostile intent and other variables, thus casting doubt on its use as a construct. The Repressor-Sensitizer and Internal-External scales intercorrelated for both sexes, but the Marlowe-Crowne scale was related to the other scales for males only, suggesting that results with this scale should not be generalized across sexes.

Role of the regulator-gene product (repressor) in catabolite repression of beta-galactosidase synthesis in Escherichia coli

1. The specific role of the lac repressor (i-gene product) in transient catabolite repression evoked by the introduction of glucose into the medium has been investigated in Escherichia coli by using mutants of the i-gene. 2. A temperature-sensitive mutant (i(TL)) is normally inducible and demonstrates transient repression when grown at 32 degrees . At 42 degrees it is about 20% constitutive and transient catabolite repression is abolished. 3. A strain carrying an amber suppressor-sensitive mutation in the i-gene is phenotypically constitutive and also fails to show transient catabolite repression. 4. Insertion of Flaci(+) into this strain restores both inducibility and transient repression. 5. It is concluded that the i-gene product interacts with the catabolite co-repressor in such a way that its affinity for the operator is increased.

Involvement of the lac regulatory genes in catabolite repression in Escherichia coli

1. Acute transient catabolite repression of beta-galactosidase synthesis, observed when glucose is added to glycerol-grown cells of Escherichia coli (Moses & Prevost, 1966), requires the presence of a functional operator gene (o) in the lactose operon. Total deletion of the operator gene abolished acute transient repression, even in the presence of a functional regulator gene (i). 2. Regulator constitutives (i(-)) also show transient repression provided that the operator gene is functional. Regulator deletion mutants (i(del)), with which to test specifically the role of the i gene, have not so far been available. 3. The above mutants, showing various changes in the lactose operon, show no alteration in the effect of glucose on induced tryptophanase synthesis. Glucose metabolism, as measured in terms of the release of (14)CO(2) from [1-(14)C]glucose and [6-(14)C]glucose, also showed no differences between strains exhibiting or not exhibiting transient repression. This suggests no change in the operation of the pentose phosphate cycle, a metabolic activity known to be of paramount importance for glucose repression of beta-galactosidase synthesis (Prevost & Moses, 1967). 4. Chronic permanent repression by glucose of beta-galactosidase synthesis (less severe in degree than acute transient repression) persists in strains in which transient repression has been genetically abolished. Constitutive alkaline-phosphatase synthesis, which shows no transient repression, also demonstrates chronic permanent repression by glucose. 5. Chloramphenicol repression also persists in mutants with no transient repression, and also affects alkaline phosphatase. It is suggested that chronic permanent repression and chloramphenicol repression are non-specific, and that they do not influence beta-galactosidase synthesis via the regulatory system of the lactose operon.