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Biomedical subjects

T Hraba

Publications and source records attributed to T Hraba.

At least 73 records · Page 4Linked to original sources
PubMed1977

Attempts to characterize cellular mechanisms of immunologic tolerance to HSA in chickens.

Partial suppression of antibody formation in neonatally induced tolerance to HSA as observed during immunization at 6 weeks of age or at a later time, is caused mainly by a rapid escape from tolerance. The following findings support this view: 1. After immunization at 4 weeks of age with a larger dose of HSA, which elicits detectable circulating antibody formation in all control birds, anti-HSA antibodies cannot be demonstrated in a large majority of tolerant chickens. 2. Surgical bursectomy performed in tolerant birds on the day of hatching or 7 or 11 days after hatching increases considerably the degree of suppression of anti-HSA antibody formation and slows down the return of reactivity to HSA. These findings suggest that new immunocompetent cells originating in the bursa are responsible for escape from tolerance in this experimental system. The existence of suppressor cells in birds tolerant to HSA was not demonstrated by the transfers of spleen cell mixtures from immune and tolerant donors to young, irradiated recipients.

Animals↗
PubMed1976

Quantitative characteristics of antibody forming cells in partial tolerance.

Direct PFC to SRBC were enumerated simultaneously by the LHL and LHG in the spleens of partially tolerant and control rats. The sensitivity of LHL was higher than that of LHG, but the factor by which the number of PFC was higher in LHL than in LHG was in the two groups similar (1.44 in tolerant and 1.47 in control group). When the plaque size distribution was studied in the LHL, a significant increase in small size plaques was observed in tolerant rats. The findings are discussed and the conclusion is reached that the decrease in AFC number and not in antibody production by individual PFC is the main factor responsible for partial tolerance.

Animals↗
PubMed1975

Different effects of bacterial lipopolysaccharide on neonatal immunological tolerance to HSA in rabbits and chickens.

Addition of bacterial lipopolysaccharide to HSA during repeated immunization of rabbits neonatally rendered tolerant to HSA led to anti-HSA antibody formation in 4 out of 5 animals. In all 6 tolerant animals immunized with HSA alone tolerance persisted after cessation of the immunization series, as shown by non-immune elimination of 125I-HSA. On the other hand, immunization with HSA together with different doses of LPS did not increase anti-HSA antibody levels in tolerant and control chickens.

Animals↗