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M C Carr

Publications and source records attributed to M C Carr.

62 records · Page 4Linked to original sources
PubMed1972

Development of cellular immunity in the human fetus: dichotomy of proliferative and cytotoxic responses of lymphoid cells to phytohemagglutinin.

The reactivity of cells in vitro was investigated with specimens from various lymphoid organs of seven human fetuses. Thymocytes responded to stimulation by phytohemagglutinin with significant increases in synthesis of DNA, but failed to produce destruction of xenogeneic target cells. In cells from bone marrow, precisely the converse pattern of reactivity to the mitogen was detected. Lymphocytes from spleen and peripheral blood demonstrated both phytohemagglutinin-dependent functions, while hepatic cells did not respond to phytohemagglutinin. Based on the striking dichotomy of phytohemagglutinin-dependent responses in fetal thymocytes and bone-marrow lymphoid cells, we conclude that phytohemagglutinin-dependent cytotoxicity and DNA synthesis are functions of different populations of lymphoid cells during human embryonic development.

Animals↗
PubMed1972

The human rosette-forming cell as a marker of a population of thymus-derived cells.

Sheep red blood cells can surround, in vitro, some human peripheral blood lymphocytes in a formation called a rosette. The number of rosetteforming cells (RFC) in 50 normal persons had a wide range (4-40%). The organs of 13 human fetuses (11-19 wk conceptional age) were examined for the presence of RFC. The thymus possessed the highest percentage of RFC, the maximum being 65% of total thymocytes in two 15-16 wk fetal specimens. Blood RFC were always present and their number slightly increased in the oldest fetuses. The bone-marrow showed 0-8% in the six fetuses studied. RFC were found in the spleen around the 13th wk and in the liver around the 17th wk of gestation. These observations lead to the hypothesis that human blood RFC may be chiefly thymic derived. Studies of patients with immunological disorders support this hypothesis: one patient with Nezelof syndrome had no blood RFC and four patients with Wiskott-Aldrich syndrome had a low number of blood RFC (1 and 1.5%). Patients with acquired hypogammaglobulinemia showed a normal percentage of RFC. With the fetal thymocytes, the percentage of inhibition with anti-mu serum increased with the fetal age to become complete in the oldest fetuses studied. Incubation of the oldest fetal thymocytes or the blood lymphocytes with anti-gamma serum of anti-mu serum completely inhibited the rosette formation. These results suggest that mu-chain determinants are present on human fetal thymocytes and blood RFC. The significance of the presence of gamma-chain determinants on these cells is unclear.

Adolescent↗