Studies of surface immunoglobulins on human B lymphocytes. III. Physiological variations of SIg+ cells in peripheral blood.

The levels of B lymphocytes bearing surface immunoglobulins in human peripheral blood were measured by immunofluorescence after pre-treatment of the cells with a low pH shock or washing at 37 degrees C. It was found that the percentages of SIg-bearing cells in an individual varied throughout the day and showed a circadian rhythm with a peak at 12 midnight and a depression at 12 noon. In addition, the levels of the B lymphocytes in the peripheral blood were shown to vary annually, being lower in the winter than in the summer.