Immune Responses in Vitro

Abstract

Interactions among macrophages (M¢),1 T cells, and precursors of antibody-producing (B) cells in the presence of antigen, mediated by direct cell-to-cell contact(s) and/or by soluble factors elaborated by one or more of the cells, are essential for development of optimal plaque-forming cell (PFC) responses to "thymus-dependent" antigens such as sheep erythrocytes (SRBC) and random terpolymer of L-glutamic acid6°-L-alanine3°-Ltyrosine ~° (GAT) by mouse spleen ceils in vitro (1-4). Recent experiments have defined some of the genetic requirements for successful physiologic interactions among antigen and these cells. First, M~b and lymphoid cells (T and B cells) need not be syngeneic for successful generation of PFC responses; allogeneic M~ support the development of PFC responses by lymphoid cells which are comparable in magnitude to responses which develop in the presence of syngeneic M~b (4-6). Thus no known genetic restrictions appear to govern the interactions of MO with T cells and B cells in the development of antibody responses in the mouse. Second, physiologic cooperation between T and B ceils requires that the T cells be syngeneic or semisyngeneic with B cells at the H-2 complex (7, reviewed in reference 8). It has been shown that identity of certain membrane molecules encoded by the H-2 complex is required for antigen-activated T cells to be able to supply the appropriate "second" stimulus required to trigger antigen-activated B cells into cycles of cell division and differentiation into mature antibody-producing cells. These membrane molecules may be the H-2 antigens themselves or other molecules coded for by the K end of the H-2 complex (8). In addition to the mechanism of T-cell-B-cell interaction requiring physical contact between crucial membrane molecules on T and B cells, humoral factors produced by activated T cells may also act on the membrane molecules on B cells to

Inhibition of proliferative and plaque-forming cell responses by human bone-marrow-derived lymphocytes from peripheral blood by antisera to the p23, 30 antigen.

“…The present studies demonstrate that the anti-p23,30, like antisera to murine Ia determinants, is markedly inhibitory to the generation of an antibody response in vitro. The kinetics of this inhibition are similar to those described in the murine system using antisera directed against I region gene products (15). In both the murine and human systems, PFC generation was inhibited to a much greater extent when the respective antisera were present during the first 48 hr of cell culture.…”

Genetic control of immune responses in vitro. VI. Experimental conditions for the development of helper T-cell activity specific for the terpolymer L-glutamic aicd60-L-alanine30-L-tyrosine10 (GAT) in nonresponder mice.

“…The amount of GAT (15)(16)(17)(18)(19)(20) ng) which, when bound to macrophages, stimulated the development of GAT-specific helper T cells (group A), was less than the minimum (1 .0 gg) amount of GAT required to induce significant suppressor T cells (group C) . In the event that the development of helper T cells We can conclude (a) that the failure of nonresponder mice to develop a GAT-specific PFC response to GAT-M-~is not due to a lack of helper T cells, nor is it due to simultaneous stimulation of suppressor T cells ; and (b) mice immunized with soluble GAT in doses too low to elicit suppressor T cells do not develop helper T cells .…”

“…We examined spleen cells from DBA/1 mice 7 days after immunization with GAT-M(P (15)(16)(17)(18)(19)(20) ng GAT) for the development of GATspecific PFC responses and found no detectable response . This finding correlated with the failure of spleen cells from DBA/1 mice to respond to GAT-M4) in vitro, but was inconsistent with the observation that DBA/1 mice immunized with GAT-M-t develop radioresistant helper T cells.…”

“…To differentiate between these two alternatives, DBA/1 mice were injected with 2 to 4 x 106 peptone-induced DBA/1 peritoneal M4) bearing [15][16][17][18][19][20] ng of GAT . After 5 wk, these mice were irradiated and examined for helper T-cell activity specific for GAT .…”

Regulation by the H-2 gene complex of macrophage-lymphoid cell interactions in secondary antibody responses in vitro.

“…M~b and helper T cells are required for development of antibody responses to GAT by responder B cells in vitro, and the defect in nonresponder mice is not in M~b (13). M~b from peptone-induced peritoneal exudates of responder and nonresponder mice bind approximately equal quantities of GAT, and these M~b bearing nanogram quantities of GAT stimulate comparable PFC responses by responder lymphoid cells (13,14,17).…”