Circulating CALLA-positive lymphocytes exhibit circadian rhythms in man

Area of Science:

• Immunology
• Hematology
• Chronobiology

Background:

• Common acute lymphoblastic leukemia antigen (CALLA), a 100,000-dalton polypeptide (P100), is primarily found on leukemic lymphoblasts, not normal lymphocytes.
• Investigating CALLA+ lymphocytes in healthy individuals can elucidate normal immune cell dynamics.

Purpose of the Study:

• To investigate the circadian rhythmicity of CALLA-positive (CALLA+) lymphocytes in healthy male subjects.
• To characterize the binding of J5 and VILA1 monoclonal antibodies to CALLA+ cells and their correlation with lymphocyte subpopulations.

Main Methods:

• Blood samples were collected every 4 hours for 24 hours from five healthy male subjects.
• Mononuclear cells were isolated, and CALLA+ cells were identified using J5 and VILA1 monoclonal antibodies.
• T- and B-cell subpopulations were analyzed, and circadian rhythms were statistically validated.

Main Results:

• A significant circadian rhythm was observed for J5-labeled CALLA+ lymphocytes, with peak numbers occurring at night (up to 1160 cells/mm³).
• VILA1-labeled CALLA+ lymphocytes also peaked nocturnally but at much lower numbers (66 cells/mm³).
• J5-labeled CALLA+ cell counts correlated with total lymphocytes, OKT3+ T cells, and OKT4+ T cells, but not with OKT8+ cells or B cells.

Conclusions:

• The study confirms circadian rhythmicity in circulating J5-labeled CALLA+ lymphocytes, with a marked nocturnal increase.
• The differential correlation patterns suggest J5 and VILA1 antibodies bind to different epitopes on the CALLA molecule.
• The nocturnal rise in J5-labeled CALLA+ cells may indicate the release of immature T lymphocytes into the peripheral blood during the night.