BEHAVIOUR OF γδTCR⁺ T CELLS DURING THE COURSE OF NONTUBERCULOUS MYCOBACTERIAL INFECTIONS AND PROLIFERATIVE RESPONSE OF HOST LYMPHOCYTES TO 65kD HEAT SHOCK PROTEIN

Abstract

In order to know the possibility that γδTCR⁺ T cells induced by Mycobacterium avium complex (MAC) infections participate in the expression of host resistance and in the occurrence of Behget disease, we examined the behaviour of them in MAC-infected host mice. In both BALB/c (Bcg^s; MAC-susceptible) and CBA/JN (Iker; MAC-resistant) strain mice, a transient but appreciable increase in the number of γδTCR⁺ T cells in the host peritoneal lymphocytes was noted around week 1 to 2 after M. intracellulare infection viaip. route. The degree of induction of γδTCR⁺ T cells was somewhat higher in CBA/JN mice than in BALB/c mice. Therefore, γδTCR⁺ T cells are partly responsible for the expression of host resistance against the MAC in the early phase of infection. However, the subsequent decrease in the level of γδTCR⁺ T cells was observed by week 5. Thus, in the case of chronic state of MAC infection, the size of γδTCR⁺ T cell-pool seems to be in normal level. This suggests that per cell activity of γδTCR⁺T cells rather than mobilizing number of them is important factor in the mechanisms for occurrence of allergic diseases including Behget disease. Although, the early increase in γδTCR⁺T cells of peritoneal cells was also observed during the course of M. fortuitum infection, the degree of induction of γδTCR⁺T cells in A/J mice (M. fortuitum-susceptible) was in similar level as that in BALB/c mice (M. fortuitum-resistant).