Correlation and modulation of Ehrlich ascites tumor growth with tumor-plasma IgA

Plasma IgA level of Ehrlich ascites tumor bearing mice showed correlation with progress of tumor growth. In PAGE analysis total plasma IgA separated into 3 major bands corresponding to mol. wt. > or = 669,000 daltons, identical to 443,000 daltons and between 443,000 and 150,000 daltons. All the three bands increased gradually with progress of tumor growth upto day 14 and then declined on day 16. Total plasma IgA isolated by anti-IgA affinity chromatography when adoptively transferred to mice inhibited tumor growth. Affinity-purified plasma IgA separated into three major peak fractions after Sephadex G-200 column chromatography which corresponded with the bands of IgA on PAGE analysis. Three Sephadex G-200 IgA fractions when adoptively transferred to tumor-bearing mice showed effect different from total IgA. High mol. wt. IgA fraction (> or = 669,000 daltons) inhibited tumor growth whereas medium mol. wt. fraction (identical to 443,000 daltons) enhanced tumor growth. The low mol. wt. IgA fraction (< 443,000 and > 150,000 daltons) had no significant effect on tumor growth. The high mol. wt. IgA fraction enhanced tumor killing ability of peripheral blood lymphocytes (PBL) and peritoneal macrophages of tumor bearer in vitro. Medium mol. wt. IgA fraction inhibited tumor-killing ability of PBL in vitro but had no significant effect on peritoneal macrophages. The low mol. wt. IgA fraction showed a mild enhancing effect on tumor-killing ability of PBL but had no significant effect on peritoneal macrophages. The results established importance of IgA in tumor growth regulation and its therapeutic potentiality. The results indicated that tumor growth modulation by tumor plasma IgA is also mediated by its effect on cellular anti-tumor immune factors of the host.