The role of immune cell subpopulations in the growth and rejection of TC‑1/A9 tumors in novel mouse strains differing in the H2‑D haplotype and NKC domain

Abstract

The present study aimed to elucidate the role of cluster of differentiation (CD)8+, CD4+, natural killer (NK), and myeloid (CD11b+) cells in the course of the growth and rejection of experimental major histocompatibility complex (MHC) class I-deficient, HPV16 E6/E7-associated TC-1/A9 tumors in mice. Stable mouse lines (F30) generated by inbreeding of Balb/c and C57BL/6 strains, which were characterized by H-2Db+d-NK1.1neg (B6-neg) and H-2Db-d+NK1.1high (Balb-high) phenotypes, were used for the present study. The novel strains spontaneously regressed tumors in 70–90% of cases. Ex vivo histological analysis of the tumor microenvironment in cryosections showed an indirect correlation between the growth of the transplanted tumor (progressor vs. regressor mice) and the proportion of immunocompetent cell infiltration in the tumors. The regressor mice exhibited a higher infiltration of tumors with CD4+ and CD8+ cells, and in Balb-high with NK cells as well, compared with the progressors. All tumor transplants also indicated a huge infiltration of CD11b+ cells, but this infiltration was not dependent on the stage of the TC-1/A9 tumor development. Depletion of individual cell subpopulations in vivo exhibited different effects on the tumor development in the two strains. Elimination of CD8-positive cells enhanced growth of TC-1/A9 tumor transplants in both hybrid stains, whereas CD4+ cell depletion affected rejection of TC-1/A9 tumors in the B6-neg mice only. Depletion of NK cells with anti-asialo GM1 antibody in the Balb-high strain led to enhancement of tumor growth, which was more pronounced after depletion of the NK1.1+ subpopulation. On the other hand, depletion of NK cells with anti-asialo GM1 in B6-neg mice did not affect the regression of TC-1/A9 tumor transplants, but increased the CD11b+ cell infiltration. In summary, these results indicate that co-operation of particular subsets of immunocompetent cells is essential for the rejection of TC-1/A9 tumor transplants. In B6-neg mice, the co-operative action of CD8+ and CD4+ cells is required, whereas in Balb-high mice, the synergy of CD8+ and NK1.1+ cells is of major importance.

Collateral Damage: What Effect Does Anti-CD4 and Anti-CD8α Antibody–Mediated Depletion Have on Leukocyte Populations?

“…Two hundred and nine publications used an in vivo approach to deplete CD4 + cells in a mouse model, of which 145 used anti-CD4 Ab injection regimens. Of these, 137 manuscripts attempted to deplete CD4 + T cells only, whereas just seven manuscripts acknowledged that any CD4 + cells could have been affected by this methodology (26)(27)(28)(29)(30)(31)(32). More than 80% of all published work performing anti-CD4 Ab-mediated depletion method used GK1.5.…”

“…Similarly, of the 809 manuscripts found on CD8 depletion, 801 manuscripts had English full texts available, and 185 papers performed anti-CD8 Ab-mediated depletion of CD8 + cells in vivo. Six articles stated that any CD8-expressing cells could have been affected (27,29,30,(33)(34)(35), whereas 178 papers did not comment on cells other than T cells. Diverse clones of anti-CD8a and anti-CD8b Abs were used, with anti-CD8a Ab clones 2.43 and 53-6.7 being the most common choices (Fig.…”