Immunoglobulins G, A, and M determined in single cells from human tonsil.

The analysis of specific proteins in single cells is described and applied to the determination of immunoglobulins G, A, and M (gammaG, gammaA, and gammaM) in lymphoid cells of the human tonsil. The number of cells containing gammaA or gammaM was much less than the number of cells containing gammaG, but the average cell content of gammaA or gammaM was much greater than the average cell content of gammaG. Similarly, in one child where relatively few cells containing gammaG were found, the average cell content of gammaG in those cells was higher than that in the other children. The limit of sensitivity of the method for each of the three immunoglobulins with the antiserums used was less than 10(-14) gram of the specific protein.