Interference between dinitrophenyl and azobenzenearsonate determinants on in vitro binding to lymphoid cells. II. Type of binding cells and studies at the level of individual lymphoid cells.

The specific binding of DNP-T₄ on lymphoid cells occurs on the surface of B-cells. This was proved both by the absence of DNP-T₄ binding in cells pretreated with anti-total mouse Ig or anti-mouse IgM sera and by the absence of significant binding on thymocytes. Moreover, splenocytes of nu/nu mice bound similar amounts of DNP-T₄ as splenocytes of CBA/C₃H or BALB/c mice. Removal of adherent cells from normal spleen populations did not decrease the amounts of DNP-T₄ bound onto the non-adherent cell population. Azobenzenearsonate (ARS) conjugates partially inhibited the specific binding of DNP-T₄ to both splenocytes of nu/nu mice and spleen-cell suspensions depleted from adherent cells. The problem of whether the inhibition of specific DNP binding brought about by treatment of the cells with ARS derivatives was expressed by the reduction of the number of binding cells was investigated by two methods. In the first, the number of lytic plaques formed by DNP-T₄ around single lymphoid cells was counted with populations treated or not with ARS derivatives. In the second, anti-TNP producing MOPC-315 cells were used for rosette formation with TNP-conjugated sheep erythrocytes, in the absence or presence of ARS derivatives. Both these methods showed that this inhibition was due to partial reduction of the number of B-cells specifically binding either DNP or TNP determinant, thus indicating that only a certain percentage of the cells bearing the specific hapten receptors are affected by treatment with ARS derivatives.