摘要:

&NA;It has been shown, using both the Lewis → B.N. and B.N. → Lewis rat strain combinations, that neonatal males are more susceptible to the induction of a high degree of immunological tolerance of skin homografts than females. Attempts to demonstrate a similar sex‐effect in mice were unsuccessful. It is suggested that the significantly greater tolerance response of male rats may reflect a slower maturation of immunologic response mechanisms in this species.

ISSN:0041-1337    

出版商:OVID    

年代:1963

数据来源: OVID

摘要:

&NA;The connective tissue cells in a large central area of the cornea were killed by freezing without apparent permanent damage to the optical properties of the cornea. The dead cells were replaced by mitosis and migration of the keratoblasts surrounding the injury. Injected H3thymidine was incorporated in the regenerating cells. The cells concerned with thymidine uptake were found in a ring shaped band immediately adjacent to and surrounding the injury. Cells further removed from the injury in the corneal periphery did not participate in this process. Most DNA synthesis, as shown by tritiated thymidine uptake, occurred during the first few days but some DNA synthesis was demonstrable as late as 7 to 9 days after injury. When the depopulated zone decreased in diameter, as new cells moved inward, the ring of regenerating (DNA synthesizing) cells became smaller. After new cells formed in the regeneration zone they migrated into the depopulated area within a few days. The central cornea, after a few weeks, became filled with cells normal in number and appearance of which about 25% were demonstrably radioactive. The tritiated thymidine label, although diluted by cell division which occurred early in the regeneration process, persisted in these cells indefinitely. Such corneas appear to be ideal material for transplantation experiments in which the persistence of donor cells could be studied. This has been accomplished in a series of preliminary experiments in which the indefinite persistence of the donor cells in corneal grafts was demonstrated.

ISSN:0041-1337    

出版商:OVID    

年代:1963

数据来源: OVID

摘要:

&NA;An investigation has been made of the sensitizing capacity in rats of orthotopic skin homografts of approximately constant size on the one hand, and of various dosages of dissociated cellular homografts administered by different routes on the other. As in mice differing by strong histocompatibility factors, primary orthotopic skin homografts are destroyed within 2 weeks; secondary grafts within 1 week; the immunity evoked by orthotopic skin homografts is long‐lasting; that elicited by low dosages of dissociated cells is short‐lived and dosage dependent. The i.p. route was found to be the most effective for immunization; sensitization evoked intradermally had a longer latency and duration; the i.v. route was effective only with relatively large numbers of cells; and the s.c. route was ineffective. Freund's adjuvant did not facilitate the evocation of sensitivity by subcutaneously inoculated splenic cells, and epidermal cell suspensions were less effective on a dosage basis than spleen cells.

ISSN:0041-1337    

出版商:OVID    

年代:1963

数据来源: OVID

摘要:

&NA;Rats injected neo‐natally for eight weeks with sheep erythrocytes showed partial or complete tolerance (suppression) when immunized at 13 weeks of age. The degree of suppression was greater for saline than for incomplete agglutinins. Sub‐lethal irradiation of the tolerant rats caused a loss of tolerance as measured by the levels of circulating saline agglutinins, incomplete agglutinins and hemolysins against sheep erythrocytes. There was a definite tendency to lose tolerance spontaneously among the tolerant non‐irradiated rats when antibodies were measured as hemolysins, but not when antibodies were measured as saline or incomplete agglutinins. These data are compatible with the hypothesis that the persistence of antigen is necessary for the maintenance of tolerance.

ISSN:0041-1337    

出版商:OVID    

年代:1963

数据来源: OVID

ISSN:0041-1337    

出版商:OVID    

年代:1963

数据来源: OVID

ISSN:0041-1337    

出版商:OVID    

年代:1963

数据来源: OVID

ISSN:0041-1337    

出版商:OVID    

年代:1963

数据来源: OVID

ISSN:0041-1337    

出版商:OVID    

年代:1963

数据来源: OVID