Effect of hemic cells on hybrid resistance

Area of Science:

• Immunology
• Hematology
• Transplantation Biology

Background:

• F1 hybrids typically resist hemopoietic tissue grafts from parental strains.
• The microenvironment of hemopoietic tissue plays a critical role in graft acceptance or rejection.

Purpose of the Study:

• To investigate the effect of parental hemic cells on F1 hybrid resistance to hemopoietic tissue grafts.
• To identify the specific cell types responsible for inhibiting hybrid resistance.
• To elucidate the mechanism underlying the inhibition of hybrid resistance.

Main Methods:

• Injection of various parental strain hemic cells into F1 hybrids.
• Assessment of the F1 hybrid's ability to resist growth of grafted hemopoietic tissue.
• Analysis of inhibitory activity from different cell populations (lymphoid, myeloid, embryonic, adult).

Main Results:

• Parental hemic cells, including those from lymph nodes, spleen, bone marrow, thymus, peritoneal macrophages, and peripheral blood leukocytes, significantly reduced F1 hybrid resistance.
• Embryonic and adult liver cells or blood erythrocytes did not inhibit hybrid resistance.
• Inhibitory activity was observed even in lymphoid cells that were immune or tolerant to hybrid antigens, suggesting it's not a graft-versus-host reaction.
• Hybrid resistance inhibitory cells maintained the inability of chimeras to express resistance for at least 2 months.

Conclusions:

• Specific parental hemic cells can inhibit F1 hybrid resistance to hemopoietic tissue grafts.
• The inhibition mechanism likely involves modulation of the hemopoietic microenvironment rather than a graft-versus-host reaction.
• These findings have implications for understanding immune tolerance and graft rejection in hybrid systems.