FIG. 4.

Representative dot plot profiles of PBMC from a control animal labeled with four MAbs after 6 days of culture in RPMI (Fig. 1B, MAb sets 1 [A to D] and 5 [E to H]). Dot plot profiles A to D, with selective and exclusion gates on 2 and CD3, show that null cells comprise two unique phenotypically distinct CD3⁻ CD2⁻ and CD3⁻ CD2⁺ populations of cells. Profile A shows the frequency of CD3⁻ and CD3⁺ cells present in gate 2. Profile B shows that the cells in gate 2 comprise four populations: CD3⁻ CD2⁻ null cells in the lower left quadrant, CD3⁺ CD2⁻ γδ T cells in the upper left quadrant, CD3⁺ CD2⁺ αβ and γδ T cells in the upper right quadrant, and CD3⁻ CD2⁺ null cells in the lower right quadrant. Profile C, with an exclusion gate on CD3, shows the frequency of CD3⁻, CD2⁻ CD3⁻, and CD2⁺ populations of null cells in gate 2. Profile D, with an exclusion gate on CD3, shows that both null cell populations, CD3⁻ CD2⁺ cells in the upper right quadrant and CD3⁻ CD2⁻ cells in the lower right quadrant, express CD25. Dot plot profiles E to H, with selective and exclusion gates on 2 and CD5, show that the two null cell populations do not express CD5 and that a subset of the null cells expresses CD6. Profile E shows the frequency of CD5⁻ and CD5⁺ cells in gate 2. Profile F shows the cells in gate 2 comprise four populations: CD5⁻ CD6⁻ null cells in the lower left quadrant, CD5⁺ γδ T cells in the upper left quadrant, CD2⁺ CD6⁺ T cells in the upper right quadrant, and CD5⁻ CD6⁺ null cells in the lower right quadrant. Profile G, with an exclusion gate on CD5, shows the frequency of CD6⁻ and CD6⁺ null cells in gate 2. Profile H, with an exclusion gate on CD5, shows the frequency of residual B-B2⁺ B cells present in the culture.