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A migration inhibition test on spleen explants from NZB mice of different ages (4, 8 and 12 months) was performed using 40 μg/mI of DNA. The results have shown increased positivity with ageing of experimental animals. [ABSTRACT FROM AUTHOR]

Immunological unresponsiveness to DNP--guinea-pig skin protein conjugate (DNP--GPSP) was induced by intravenous injections of dinitrobenzenesulphonic acid (DNBSO3) given before, simultaneously, or after sensitization with DNP-GPSP. The increased DNA synthesis in vitro by lymph node or peritoneal exudate lymphocytes from unresponsive guinea-pigs was suppressed only in animals tolerized by pretreatment with DNBSO3. The majority of guinea-pigs with the other two types of unresponsiveness showed an increased [³H]thymidine incorporation into lymph node--but not into peritoneal exudate lymphocytes. From these results two conclusions may be drawn: (1) the mechanism of unresponsiveness induced during the primary response is similar to that of desensitization and different from that of `classical' tolerance; (2) tolerogen given before the sensitization prevents both the increased DNA synthesis by lymph node and peritoneal exudate lymphocytes and the skin reaction. Tolerogen given during the primary response or after the sensitization prevents increased DNA synthesis by peripheral lymphoid cells (peritoneal exudate lymphocytes) and the skin reaction, whereas lymph node lymphocytes showed increased DNA synthesis. [ABSTRACT FROM AUTHOR]

Optimum conditions were determined for the stimulation of DNA synthesis in C58 spleen cells by phytohaemagglutinin and allogeneic BALB spleen cells. Maximum stimulation occurred in 3 days in both cases. The rate of DNA synthesis was constant over a 4-hour labelling period with tritiated thymidine. DNA synthesis was significantly enhanced by 15 mM bicarbonate. The peak response of C58 spleen cells to PHA and allogeneic BALB spleen cells occurred when the mice were 3-7 months old; it decreased thereafter. This finding is discussed in relation to age-dependent immune polioencephalomyelitis in C58 mice. [ABSTRACT FROM AUTHOR]

Cryoglobulin production in rabbits immunized with streptococcal vaccines began about 3 weeks after immunization began and maximum yields from fresh immune sera ranged from <01 mg/mi to >6 mg/mI in individual rabbits. The cryoglobulins contained IgM and IgG, antiglobulin that was mainly IgM, IgG homogeneous antibodies to streptococci, and DNA. It is postulated that cryoglobulins are formed in two stages: alteration of IgG followed by antigen- antibody precipitation with antiglobulin. [ABSTRACT FROM AUTHOR]

The ability of C57BL, C3H, and A strain marrow cells to proliferate on transplantation into irradiated isogenic, F1 hybrid, and backcross progeny mice has been investigated by the spleen-colony technique and by measuring the newly-formed DNA in the recipient spleen with [131I] 5-iododeoxyuridine. Transplants of C57BL cells grew poorly in (A × C57BL) F1 and in (C57BL × C3H) F1 and reciprocal hybrids, as compared with isogenic and allogeneic hosts, whereas C3H and A strain marrow grafts were successful in isogenic, F1 hybrid and backcross recipients. In segregating backcross progeny, i.e. in offspring from F1 hybrid females mated to C57BL males, the frequency of success or failure of the C57BL grafts suggested that the trait was controlled by a single pair of genetic determinants at an autosomal locus. The latter is apparently linked with, or part of, the H-2 region in the IXth linkage group. The experimental evidence suggested also that the failure of C57BL haemopoietic cell grafts in H-2 heterozygotes was not related to exhaustion of donor cells by excess of recipient isoantigen but rather to lack of expression in the heterozygotes of histocompatibility-related growth requirements yet undefined. These requirements are specific for haemopoietic cells, but not for skin grafts, and resulted most probably from the effect of genetic (inter-allelic) interaction involving H-2 or an H-2-linked locus. [ABSTRACT FROM AUTHOR]