Investigations on the pool size, proliferative state and differentiation pattern of splenic CFUC in normal dogs.

In the present study we investigated the absolute numbers of granulocytic progenitor cells (CFUc) in the spleens of adult normal dogs, their differentiation pattern and also their proliferative state. Between 10 and 40 times as many CFUc were found in the spleens of individual dogs as were present in the total blood volume at the same time under physiological conditions. About 16% of the splenic CFUc were in the DNA synthetic phase. In spite of the presence of CFUc in the splenic tissue, there was a lack of morphologically identifiable granulocytic precursor cells and hence no extramedullary granulocyte production. The similarities between circulating CFUc and the splenic CFUc with respect to their differentiation pattern in vitro and their cell cycle state suggest that the CFUc that reside in the splenic tissue are identical to thea CFUc population in the circulation.

The repopulation of lymph nodes of dogs after 1200 R whole-body x-irradiation and intravenous administration of mononuclear blood leukocytes.

Fresh and cryopreserved autologous or allogeneic mononuclear blood cells (MBCs) intravenously injected in 1200 R total-body x-irradiated dogs repopulated lymph nodes within 10 days after tranfusion. Several parameters of the lymphopoietic regeneration were correlated with the number of cells transfused and with the number of colony-forming units contained in the cell suspension when they were cultured in agar (CFUc). Values within the normal or close to normal range were reached in the mesenteric nodes of most of the animals transfused with 10 X 10(9) MBC or more. These values were obtained when 5 X 10(5) CFUc or more were transfused. Axillary nodes showed lower values than mesenteric nodes. They were mostly under the normal range but well over those of the irradiated controls. Frozen and thawed MBCs seem to be as effective as fresh cells for lymphopoietic restoration. The mesenteric nodes of dogs transfused with allogeneic MBCs showed higher cellularity and larger cortical-paracortical areas than those of dogs tranfused with approximately the same number of autologous cells. The repopulation of lymph nodes parallels that of the marrow.

[Collection of hematopoietic stem cells from canine peripheral blood and their ability to regenerate hematopoiesis]. / Untersuchungen über die Gewinnung hämopoetischer Stammzellen aus dem peripheren Blut von Hunden und über ihre Fähigkeit, die Blutzellbildung zu regenerieren

A procedure is presented for the collection of a large number of hemopoietic stem cells from the peripheral blood of dogs by means of a single leukapheresis using the NCI-IBM Blood Cell Separator. In the course of a leukapheresis of about 285 min duration a mean of 23 x 10-9 leukocytes is collected from the blood. The hemopoietic stem cells among such separated leukocytes initiate repopulation of bone marrow within 10 days after whole body X-irradiation with 1200 R. The cell numbers in a defined histological section of femoral bone marrow are evaluated 9 to 10 days after irradiation and subsequent autologous transfusion of 6.72 x 10-9 separated mononuclear leukocytes. The results indicate that the bone marrow cell numbers of transfused dogs are significantly greater than in dogs given only 1200 R and reach a level of approximately 49% of the normal value. Possible ways of increasing the yield of hemopoietic stem cells from the peripheral blood will be considered.

Histocompatibility testing in dogs. II. Leukocyte typing in relation to the mixed lymphocyte culture (MLC) reactivity.

The correlation between MLC reactivity (LD) and serological leukocyte typing (SD) was studied in a beagle colony. Disparity for a serologically defined non-DL-A lymphocyte antigen did not correlate with MLC reactivity. Lymphocytes of colony members with common ancestors and SD identical DL-A haplotypes did not stimulate each other in the MLC. This implies that LD typing in the beagle coolony can be generally predicted by DL-A SD typing. Consequently, lymphocytes of sibs homozygous for a given DL-A SD haplotype could be shown, with few exceptions, to be also homozygous for MLC determinants. Cells of these homozygous sibs can be used in MLC typing as reference cells for DL-A LD specificities. Two exceptions to the expected linkage between DL-A SD typing and MLC reactivity were found. These findings could not be explained by recombination with the DL-A region assuming a single major LD locus coding for MLC. Thus, suggestive evidence for more than one single LD locus has been obtained.