In ragweed-sensitive and ragweed non-sensitive subjects the proportions of T lymphocytes bearing receptors for the Fc portion of IgG (Tγ) and IgM (Tμ) were examined as obtained from the blood, and after treatment in vitro with ragweed antigen E or concanavalin-A.
The proportion of Tγ and Tμ cells, from the peripheral blood of ragweed-sensitive and ragweed non-sensitive persons, untreated in vitro, were not statistically different. However when T cells from ragweed-sensitive subjects were exposed to ragweed antigen E, the Tμ subpopulation was significantly increased (P < 0.001) without change in the Tγ population. The reverse change occurred when cells of ragweed non-sensitive subjects were treated with antigen E; there was an increase in the Tγ subpopulation (P= 0.01) but no change in number of the Tμ cells. Cells from both the sensitive and non-sensitive groups showed increase in number of Tγ and reduced numbers of Tμ cells when incubated with concanavalin A.
Since Tγ and Tμ cells appear to have a regulatory function on B lymphocyte differentiation and antibody production, the pattern of responses of Tγ and Tμ subpopulations in vitro to antigen E in ragweed-sensitive and ragweed non-sensitive subjects may reflect a difference in the cellular control of the immune response to ragweed antigen E.